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21 results on '"Jean-Philippe Duvel"'

1. Self‐Aggregation of Convective Clouds With Interactive Sea Surface Temperature

Author

Fabio D'Andrea, Jean-Philippe Duvel, Caroline Muller, Sara Shamekh, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Convection, 010504 meteorology & atmospheric sciences, Radiative cooling, self‐aggregation, Tropical Convection, Atmospheric Composition and Structure, cloud‐resloving simulation, 010502 geochemistry & geophysics, Atmospheric sciences, Surface pressure, 01 natural sciences, lcsh:Oceanography, sea surface temperature, Environmental Chemistry, lcsh:GC1-1581, Air/Sea Interactions, lcsh:Physical geography, ComputingMilieux_MISCELLANEOUS, Research Articles, Physics::Atmospheric and Oceanic Physics, convection, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Mesoscale Meteorology, Global and Planetary Change, Anomaly (natural sciences), Air/Sea Constituent Fluxes, Sea surface temperature, Boundary layer, Circulation (fluid dynamics), 13. Climate action, [SDU]Sciences of the Universe [physics], [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDE]Environmental Sciences, Atmospheric Processes, Slab, General Earth and Planetary Sciences, Clouds and Cloud Feedbacks, Ocean/Atmosphere Interactions, lcsh:GB3-5030, Atmospheric, Geology, Natural Hazards, Oceanography: Physical, Research Article
Abstract

This study investigates the feedbacks between an interactive sea surface temperature (SST) and the self‐aggregation of deep convective clouds, using a cloud‐resolving model in nonrotating radiative‐convective equilibrium. The ocean is modeled as one layer slab with a temporally fixed mean but spatially varying temperature. We find that the interactive SST decelerates the aggregation and that the deceleration is larger with a shallower slab, consistent with earlier studies. The surface temperature anomaly in dry regions is positive at first, thus opposing the diverging shallow circulation known to favor self‐aggregation, consistent with the slower aggregation. But surprisingly, the driest columns then have a negative SST anomaly, thus strengthening the diverging shallow circulation and favoring aggregation. This diverging circulation out of dry regions is found to be well correlated with the aggregation speed. It can be linked to a positive surface pressure anomaly (PSFC), itself the consequence of SST anomalies and boundary layer radiative cooling. The latter cools and dries the boundary layer, thus increasing PSFC anomalies through virtual effects and hydrostasy. Sensitivity experiments confirm the key role played by boundary layer radiative cooling in determining PSFC anomalies in dry regions, and thus the shallow diverging circulation and the aggregation speed., Key Points An interactive sea surface temperature (SST) has a deceleration‐acceleration impact on aggregation depending on SST response to dryingThe deceleration‐acceleration is due to first warming (enhanced shortwave) and second cooling (enhanced longwave) of surface in dry regionsA high‐pressure anomaly that forms in dry regions drives a shallow circulation that explains the speed of aggregation

Published
2020
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2. On vortices initiated over West Africa and their impact on North Atlantic tropical cyclones

Author

Jean-Philippe Duvel, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Atmospheric Science, Oceanography, Geography, 010504 meteorology & atmospheric sciences, 13. Climate action, [SDE]Environmental Sciences, Tropical cyclone, 010502 geochemistry & geophysics, 01 natural sciences, Geology, 0105 earth and related environmental sciences, Vortex, West africa
Abstract

Numerous low and mid-level vortices are initiated respectively north and south of 15°N in West Africa and enter the North Atlantic where they may trigger cyclogenesis. Applying an objective vortex tracking algorithm on 38 years of meteorological re-analysis, this work investigates the vortex origin and their role in cyclogenesis with an emphasis on: (i) orography, (ii) seasonal variations and, (iii) merge between low and mid-level vortex tracks. North path vortices are mostly initiated downstream of Hoggar Mountains (5°E, 24°N) and south path vortices are mostly initiated downstream of Fouta Djallon Mountains (15°W, 10°N). About 55% of cyclogeneses in the Main Development Region (MDR: east of 60°W; 5 to 20°N) is associated with vortices initiated on the continent east of 10°W. MDR cyclonic activity is governed by seasonal and interannual variations of the local Genesis Potential Index (maximal in August-September) and not by the number of vortices entering the Ocean. North path vortices, which are more numerous in July, are thus less cyclogenetic compared to south path vortices that are more numerous in August-September. Considering together vortices initiated on the continent and near the coast, about 20% of the cyclogeneses are associated with merge of north and south path vortices and about 14% with north path vortices only. The remaining part is mostly associated with south path vortices. In addition, south path vortices with greater intensity and vertical development between Greenwich and the coast are more cyclogenetic.

Published
2020
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3. How do ocean warm anomalies favor the aggregation of deep convective clouds?

Author

Fabio D'Andrea, Sara Shamekh, Jean-Philippe Duvel, Caroline Muller, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre National de la Recherche Scientifique (CNRS), Département des Géosciences - ENS Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, 13. Climate action, 0103 physical sciences, [SDE]Environmental Sciences, Geophysics, Anomaly (physics), 010303 astronomy & astrophysics, 01 natural sciences, Geology, 0105 earth and related environmental sciences
Abstract

We investigate the role of a warm sea surface temperature (SST) anomaly (hot spot of typically 3 to 5 K) on the aggregation of convection using cloud-resolving simulations in a nonrotating framework. It is well known that SST gradients can spatially organize convection. Even with uniform SST, the spontaneous self-aggregation of convection is possible above a critical SST (here 295 K), arising mainly from radiative feedbacks. We investigate how a circular hot spot helps organize convection, and how self-aggregation feedbacks modulate this organization. The hot spot significantly accelerates aggregation, particularly for warmer/larger hot spots, and extends the range of SSTs for which aggregation occurs; however, at cold SST (290 K) the aggregated cluster disaggregates if we remove the hot spot. A large convective instability over the hot spot leads to stronger convection and generates a large-scale circulation which forces the subsidence drying outside the hot spot. Indeed, convection over the hot spot brings the atmosphere toward a warmer temperature. The warmer temperatures are imprinted over the whole domain by gravity waves and subsidence warming. The initial transient warming and concomitant subsidence drying suppress convection outside the hot spot, thus driving the aggregation. The hot-spot-induced large-scale circulation can enforce the aggregation even without radiative feedbacks for hot spots sufficiently large/warm. The strength of the large-scale circulation, which defines the speed of aggregation, is a function of the hot spot fractional area. At equilibrium, once the aggregation is well established, the moist convective region with upward midtropospheric motion, centered over the hot spot, has an area surprisingly independent of the hot spot size.

Published
2019
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4. Tropospheric turbulence over the tropical open ocean: Role of gravity waves

Author

Masaki Katsumata, Richard Wilson, Jennifer L. Davison, Weixin Xu, François Lott, Hugo Bellenger, Jean-Philippe Duvel, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Lower Atmosphere Research Group, LLC, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Atmospheric Science [Fort Collins], Colorado State University [Fort Collins] (CSU), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
Convection, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, Turbulence, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Instability, Troposphere, Wavelength, Convective instability, 13. Climate action, 14. Life underwater, Gravity wave, Geology, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences
Abstract

A large set of soundings obtained in the Indian Ocean during three field campaigns is used to provide statistical characteristics of tropospheric turbulence and its link with gravity wave (GW) activity. The Thorpe method is used to diagnose turbulent regions of a few hundred meters depth. Above the mixed layer, turbulence frequency varies from ~10% in the lower troposphere up to ~30% around 12-km height. GWs are captured by their signature in horizontal wind, normalized temperature, and balloon vertical ascent rate. These parameters emphasize different parts of the wave spectrum from longer to shorter vertical wavelengths. Composites are constructed in order to reveal the vertical structure of the waves and their link with turbulence. The relatively longer-wavelength GWs described by their signature in temperature (GWTs) are more active in the lower troposphere, where they are associated with clear variations in moisture. Turbulence is then associated with minimum static stability and vertical shear, stressing the importance of the former and the possibility of convective instability. Conversely, the short waves described by their signature in balloon ascent rate (GWws) are detected primarily in the upper troposphere, and their turbulence is associated with a vertical shear maximum, suggesting the importance of dynamic instability. Furthermore, GWws appear to be linked with local convection, whereas GWTs are more active in suppressed and dry phases in particular of the Madden–Julian oscillation. These waves may be associated with remote sources, such as organized convection or local fronts, such as those associated with dry-air intrusions.

Published
2017
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5. Understanding Madden-Julian-Induced sea surface temperature variations in the North Western Australian Basin

Author

Stéphane Pous, Hugo Bellenger, Jean-Philippe Duvel, Jérôme Vialard, Matthieu Lengaigne, Kyla Drushka, Variabilité climatique tropicale et globale (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Couplage physique-biogéochimie-carbone (PHYBIOCAR), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Air-sea interactions, Wind stress, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), 01 natural sciences, Madden-Julian Oscillation, 14. Life underwater, Argo, 0105 earth and related environmental sciences, Intraseasonal variations, 010505 oceanography, Air-sea fluxes, Madden–Julian oscillation, Ocean general circulation model, Sea surface temperature, Ocean mixed layer, Heat flux, 13. Climate action, Climatology, Geology
Abstract

The strongest large-scale intraseasonal (30-110 day) sea surface temperature (SST) variations in austral summer in the tropics are found in the eastern Indian Ocean between Australia and Indonesia (North-Western Australian Basin, or NWAB). TMI and Argo observations indicate that the temperature signal (std. similar to 0.4 A degrees C) is most prominent within the top 20 m. This temperature signal appears as a standing oscillation with a 40-50 day timescale within the NWAB, associated with similar to 40 Wm(-2) net heat fluxes (primarily shortwave and latent) and similar to 0.02 Nm(-2) wind stress perturbations. This signal is largely related to the Madden-Julian Oscillation. A slab ocean model with climatological observed mixed-layer depth and an ocean general circulation model both accurately reproduce the observed intraseasonal SST oscillations in the NWAB. Both indicate that most of the intraseasonal SST variations in the NWAB in austral winter are related to surface heat flux forcing, and that intraseasonal SST variations are largest in austral summer because the mixed-layer is shallow (similar to 20 m) and thus more responsive during that season. The general circulation model indicates that entrainment cooling plays little role in intraseasonal SST variations. The larger intraseasonal SST variations in the NWAB as compared to the widely-studied thermocline-ridge of the Indian Ocean region is explained by the larger convective and air-sea heat flux perturbations in the NWAB.

Published
2012
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6. Tropical variability and stratospheric equatorial waves in the IPSLCM5 model

Author

Jean-Philippe Duvel, L. Guez, Pauline Maury, François Lott, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
Quasi-biennial oscillation, Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Atmospheric wave, Equatorial waves, Forcing (mathematics), 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Physics::Geophysics, Troposphere, symbols.namesake, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Middle latitudes, Climatology, symbols, Kelvin wave, Stratosphere, Geology, Physics::Atmospheric and Oceanic Physics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract

International audience; The atmospheric variability in the equatorial regions is analysed in the Earth System Model pre-industrial simulation done at IPSL in the framework of CMIP5. We find that the model has an interannual variability of about the right amplitude and temporal scale, when compared to the El-Niño Southern Oscillation (ENSO), but that is too confined to the western Pacific. At the intra-seasonal periods, the model variability lacks of large-scale organisation, and only produces one characteristic Madden-Julian Oscillation every 10 winters typically. At shorter time-scales and in the troposphere, the model has Rossby and Kelvin Convectively Coupled Equatorial Waves (CCEWs), but underestimates the Kelvin CCEWs signal on OLR. In the model stratosphere, a composite analysis shows that the Temperature and velocities fluctuations due to the Kelvin waves are quite realistic. In the model nevertheless, the stratospheric waves are less related to the convection than in the observations, suggesting that their forcing by the midlatitudes plays a larger role. Still in the model, the Kelvin waves are not predominantly occurring during the life cycle of the tropospheric Kelvin CCEWs, a behaviour that we find to be dominant in the observations. The composite analysis is also used to illustrate how the waves modify the zonal mean-flow, and to show that the model Kelvin waves are too weak in this respect. This illustrates how a model can have a reasonable Kelvin waves signal on the velocities and temperature, but can at the same time underestimate their amplitude to modify the mean flow. We also use this very long simulation to establish that in the model, the stratospheric equatorial waves are significantly affected by ENSO, hence supporting the idea that the ENSO can have an influence on the Quasi-Biennial Oscillation. © 2011 Springer-Verlag.

Published
2011
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7. Kelvin and Rossby-gravity wave packets in the lower stratosphere of some high-top CMIP5 models

Author

François Lott, Seiji Yukimoto, Jean-Philippe Duvel, Elisa Manzini, Marco Giorgetta, Steven C. Hardiman, Pauline Maury, Shingo Watanabe, Sébastien Denvil, N. Butchart, Chiara Cagnazzo, John Scinocca, Thomas Krismer, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), United Kingdom Met Office [Exeter], Istituto di Scienze dell'Atmosfera e del Clima (ISAC), Consiglio Nazionale delle Ricerche [Roma] (CNR), Max-Planck-Institut für Meteorologie (MPI-M), Max-Planck-Gesellschaft, Canadian Centre for Climate Modelling and Analysis (CCCma), Environment and Climate Change Canada, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Climate Research Department [MRI Tsukuba], Meteorological Research Institute [Tsukuba] (MRI), Japan Meteorological Agency (JMA)-Japan Meteorological Agency (JMA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)

Subjects
Quasi-biennial Oscillation, Atmospheric Science, Rossby gravity waves, Wave packet, Atmospheric sciences, Physics::Geophysics, CMIP5 models, symbols.namesake, Kelvin waves, Earth and Planetary Sciences (miscellaneous), Gravity wave, Stratosphere, Physics::Atmospheric and Oceanic Physics, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Quasi-biennial oscillation, Physics, Coupled model intercomparison project, Atmospheric wave, Convectively coupled waves, Geophysics, Amplitude, 13. Climate action, Space and Planetary Science, symbols, Kelvin wave
Abstract

International audience; We analyze the stratospheric Kelvin and Rossby-gravity wave packets with periods of a few days in nine high-top (i.e., with stratosphere) models of the fifth Coupled Model Intercomparison Project (CMIP5). These models simulate realistic aspects of these waves and represent them better than the tropospheric convectively coupled waves analyzed in previous studies. There is nevertheless a large spread among the models, and those with a quasi-biennial oscillation (QBO) produce larger amplitude waves than the models without a QBO. For the Rossby-gravity waves this is explained by the fact that models without a QBO never have positive zonal mean zonal winds in the lower stratosphere, a situation that is favorable to the propagation of Rossby-gravity waves. For the Kelvin waves, larger amplitudes in the presence of a QBO is counter intuitive because Kelvin waves are expected to have larger amplitude when the zonal mean zonal wind is negative, and this is always satisfied in models without a QBO. We attribute the larger amplitude to the fact that models tuned to have a QBO require finer vertical resolution in the stratosphere. We also find that models with large precipitation variability tend to produce larger amplitude waves. However, the effect is not as pronounced as was found in previous studies. In fact, even models with weak precipitation variability still have quite realistic stratospheric waves, indicating either that (i) other sources can be significant or that (ii) the dynamical filtering mitigates the differences in the sources between models. © 2014. American Geophysical Union. All Rights Reserved.

Published
2014
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8. Moist processes during MJO events as diagnosed from water isotopic measurements from the IASI satellite

Author

Cathy Clerbaux, John Worden, A. Wiegele, Sandrine Bony, Obbe Tuinenburg, Jean-Lionel Lacour, Jean-Philippe Duvel, Matthias Schneider, Pierre-François Coheur, Naoyuki Kurita, Nicholas M. Deutscher, and Camille Risi

Subjects
Atmospheric Science, Atmospheric models, Advection, Humidity, Madden–Julian oscillation, Atmospheric sciences, Atmosphere, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Earth and Planetary Sciences (miscellaneous), Environmental science, Precipitation, Tropical cyclone, Water vapor
Abstract

This study aims to investigate some characteristics of the moist processes of the Madden-Julian oscillation (MJO), by making use of joint HDO (or δD) and H2O vapor measurements. The MJO is the main intraseasonal mode of the tropical climate, but is hard to properly simulate in global atmospheric models. The joint use of δD-H2O diagnostics yields additional information compared to sole humidity measurements. We use mid-tropospheric Infrared Atmospheric Sounding Interferometer (IASI) satellite δD and H2O measurements to determine the mean MJO humidity and δD evolution. Moreover, by making use of high temporal resolution data, we determine the variability in this evolution during about eight MJO events from 2010 to 2012 (including those monitored during the CINDY/DYNAMO campaign). This data has a higher spatio-temporal coverage than previous δD measurements, enabling the sampling of individual MJO events. IASI measurements over the Indian Ocean confirm earlier findings that the moistening before the precipitation peak of an MJO event is due to water vapor slightly enriched in HDO. There is then a HDO depletion around the precipitation peak that also corresponds to the moister environment. Most inter-event variability determined in the current study occurs 5 to 10 days after the MJO event. In 75% of the events, humidity decreases while the atmosphere remains depleted. In a quarter of the events, humidity increases simultaneously with an increase in δD. After this, the advection of relatively dry and enriched air brings back the state to the mean. Over the maritime continent, δD-H2O cycles are more variable on timescales shorter than the MJO and the inter-event variability is larger than over the Indian Ocean. The sequence of moistening and drying processes as revealed by the q-δD cycles can be used as a benchmark to evaluate the representation of moist processes in models. This is done here by comparing observations to simulations of the isotope enabled LMDZ GCM nudged with reanalysis wind fields. These simulations also give informations to investigate possible physical origins of the observed q-δD cycles.

Published
2015
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9. Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

Author

Ionela Musat, Marion Marchand, Slimane Bekki, Josefine Ghattas, C. Levy, Thierry Fichefet, Sophie Szopa, Hugo Bellenger, Franck Lefèvre, Yann Meurdesoif, Frédérique Cheruy, Yves Balkanski, Nicolas Viovy, Pascal Terray, Laurent Bopp, A. Lahellec, Olivier Aumont, Jan Polcher, Masa Kageyama, Jean-Louis Dufresne, Pierre Friedlingstein, Frédéric Hourdin, Patricia Cadule, Juliette Mignot, David Cugnet, François Lott, Arnaud Caubel, Gurvan Madec, Patrick Brockmann, Jean-Philippe Duvel, L. Guez, Eric Guilyardi, Sandrine Bony, Laurent Fairhead, Pascale Braconnot, Martial Mancip, Marie-Pierre Lefebvre, Olivier Marti, Rachid Benshila, N. de Noblet, Anne Cozic, Gerhard Krinner, Sonia Labetoulle, Sylvie Joussaume, Didier Swingedouw, C. Talandier, S. Parouty, Francis Codron, Michael Schulz, Abderrahmane Idelkadi, Nicolas Vuichard, James Lloyd, Sébastien Masson, S. Flavoni, Christian Ethé, Marie-Alice Foujols, Didier Hauglustaine, Jean-Yves Grandpeix, Sébastien Denvil, Z. X. Li, Catherine Rio, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Institut Pierre-Simon-Laplace (IPSL), École normale supérieure - Paris (ENS Paris)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Centre Georges Lemaître for Earth and Climate Research [Louvain] (TECLIM), Earth and Life Institute [Louvain-La-Neuve] (ELI), Université Catholique de Louvain (UCL)-Université Catholique de Louvain (UCL), College of Engineering, Mathematics and Physical Sciences [Exeter] (EMPS), University of Exeter, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Calcul Scientifique (CALCULS), Extrèmes : Statistiques, Impacts et Régionalisation (ESTIMR), Université Catholique de Louvain = Catholic University of Louvain (UCL)-Université Catholique de Louvain = Catholic University of Louvain (UCL), Modélisation du climat (CLIM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Climate, [SDE.MCG]Environmental Sciences/Global Changes, 0207 environmental engineering, Climate commitment, Climate change, 02 engineering and technology, 01 natural sciences, Earth System Model, Climate projections, CMIP5, RCP scenarios, CMIP3, 020701 environmental engineering, 0105 earth and related environmental sciences, Aerosols, Coupled model intercomparison project, Global warming, Representative Concentration Pathways, Carbon cycle, Greenhouse gases, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, 13. Climate action, Land use changes, Allowable emissions, Climatology, Paleoclimate Modelling Intercomparison Project, Environmental science, Climate model, Downscaling
Abstract

International audience; We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes.

Published
2013
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10. An event-by-event assessment of tropical intraseasonal perturbations for general circulation models

Author

Gilles Bellon, Hugo Bellenger, Jean-Philippe Duvel, Marine Remaud, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Variabilité climatique tropicale et globale (VARCLIM), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636))

Subjects
Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Baroclinity, [SDE.MCG]Environmental Sciences/Global Changes, Perturbation (astronomy), Intraseasonal perturbations, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Physics::Geophysics, Madden Julian Oscillation, Barotropic fluid, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Coupled general circulation models, Madden–Julian oscillation, Tropical variability, Amplitude, Boreal, 13. Climate action, Climatology, General Circulation Model, Convective parameterization, Environmental science
Abstract

International audience; We detect and characterize each large-scale intraseasonal perturbation in observations (1979-2009) and in coupled general circulation models of Institut Pierre Simon Laplace (IPSL) and of Centre National de Recherches Météorologiques (CNRM). These ensembles of intraseasonal perturbations are used to assess the skill of the two models in an event-by-event approach. This assessment addresses: (1) the planetary-scale (i.e. the whole Indo-Pacific area) extent of wind and rainfall perturbations and the reproducibility of the perturbation patterns for a given season; (2) the size and amplitude of rainfall and wind anomalies at basin-scale (i.e. for a particular phase of the perturbation) and; (3) the evolution of the vertical structure of the perturbations (U, T and RH) for selected events. The planetary-scale extent of rainfall perturbations is generally too small for both models. This extent is also small for the wind perturbation in the IPSL model, but is correct, or even too large in boreal winter, for the CNRM model. The reproducibility of the planetary-scale patterns is exaggerated for wind perturbations in the CNRM model and is very poor for all parameters in the IPSL model. Over the Indian Ocean during boreal winter, rainfall and wind anomalies at basin-scale are too large for the CNRM model and too small for the IPSL model. The CNRM model gives a realistic baroclinic perturbations structure for wind, moisture and temperature, but with too large amplitude due in part to a zonally extended rainfall anomaly over the eastern Indian Ocean and the Maritime Continent. The IPSL model gives a realistic response for low-level wind only. Temperature and moisture perturbations are barotropic with a wrong warm anomaly at rainfall maximum and there is no gradual increase in low-level moisture prior to this rainfall maximum. These results suggest that this version of the IPSL model is unable to initiate the coupling between the convection and the dynamic necessary to develop the perturbation. It is difficult to say if this is due to, or is at the origin of the lack of basin-scale organization of the convection. We discuss the likely role of the convective schemes in the differences found between these two versions of the CNRM and IPSL models.

Published
2013
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11. The event-to-event variability of the boreal winter MJO

Author

Jean-Philippe Duvel and Hugo Bellenger

Subjects
Convection, 010504 meteorology & atmospheric sciences, Equator, Perturbation (astronomy), Madden–Julian oscillation, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Geophysics, Amplitude, Boreal, 13. Climate action, Climatology, General Earth and Planetary Sciences, Outgoing longwave radiation, Longitude, Geology, 0105 earth and related environmental sciences
Abstract

[1] During boreal winters, perturbations of the convection by the Madden-Julian Oscillation (MJO) peak over three basins distributed in longitude south of the Equator: the eastern Indian Ocean (IO), the south of the Maritime Continent (MC) and the western Pacific Ocean (PO). We use the observed Outgoing Longwave Radiation (OLR) and low-level wind to identify and characterize all wintertime MJO events between 1979 and 2010. There is a large event-to-event variability with some MJO events organized at the planetary-scale having their amplitude well distributed over the 3 basins and some showing only basin-scale organization with a convective perturbation peaking over one or two basins. The average of the MJO amplitude for the three basins shows an intriguing decadal variability consistent for both OLR and low-level wind. The disparity between the 3 basins is dominated by an alternation between MJO amplitude peaking on either the Indian or the Pacific Ocean. This Indo-Pacific alternation, depicted by an Indo-Pacific Index (IPI), is partly related to ENSO. In El Nino conditions, there is not only an extension of the MJO perturbation further east, but also an increase of the MJO perturbation over the western Pacific and a diminution of the MJO perturbation over the eastern Indian Ocean.

Published
2012
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12. Factors controlling January-April rainfall over southern India and Sri Lanka

Author

Pascal Terray, D. Shankar, Jérôme Vialard, Ravi S. Nanjundiah, S. S. C. Shenoi, Jean-Philippe Duvel, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre for Atmospheric and Oceanic Sciences [Bangalore] (CAOS), Indian Institute of Science [Bangalore] (IISc Bangalore), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Equator, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, El Nino/Southern Oscillation, Madden-Julian Oscillation, 0105 earth and related environmental sciences, Anomaly (natural sciences), Rainfall interannual variability over India, Subsidence (atmosphere), Madden–Julian oscillation, Oscillation, Sea surface temperature, La Niña, Geography, Oceanography, 13. Climate action, Climatology, Teleconnections, El Niño/Southern Oscillation, El NinoSouthern, Teleconnection
Abstract

International audience; Most of the annual rainfall over India occurs during the Southwest (June-September) and Northeast (October-December) monsoon periods. In March 2008, however, Southern peninsular India and Sri Lanka received the largest rainfall anomaly on record since 1979, with amplitude comparable to summer-monsoon interannual anomalies. This anomalous rainfall appeared to be modulated at intraseasonal timescale by the Madden Julian Oscillation, and was synchronous with a decaying La Niña event in the Pacific Ocean. Was this a coincidence or indicative of a teleconnection pattern? In this paper, we explore factors controlling rainfall over southern India and Sri Lanka between January and April, i.e. outside of the southwest and northeast monsoons. This period accounts for 20% of annual precipitation over Sri Lanka and 10% over the southern Indian states of Kerala and Tamil Nadu. Interannual variability is strong (about 40% of the January-April climatology). Intraseasonal rainfall anomalies over southern India and Sri Lanka are significantly associated with equatorial eastward propagation, characteristic of the Madden Julian Oscillation. At the interannual timescale, we find a clear connection with El Niño-Southern Oscillation (ENSO); with El Niños being associated with decreased rainfall (correlation of -0.46 significant at the 98% level). There is also a significant link with local SST anomalies over the Indian Ocean, and in particular with the inter-hemispheric sea surface temperature (SST) gradient over the Indian Ocean (with colder SST south of the equator being conducive to more rainfall, correlation of 0.55 significant at the 99% level). La Niñas/cold SSTs south of the equator tend to have a larger impact than El Niños. We discuss two possible mechanisms that could explain these statistical relationships: (1) subsidence over southern India remotely forced by Pacific SST anomalies; (2) impact of ENSO-forced regional Indian Ocean SST anomalies on convection. However, the length of the observational record does not allow distinguishing between these two mechanisms in a statistically significant manner.

Published
2011
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13. An evaluation metric for intraseasonal variability and its application to CMIP3 twentieth-century simulations

Author

Prince K. Xavier, Jean-Philippe Duvel, Pascale Braconnot, Francisco J. Doblas-Reyes, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), European Centre for Medium-Range Weather Forecasts (ECMWF), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Coupled model intercomparison project, 010504 meteorology & atmospheric sciences, Perturbation (astronomy), Weather and climate, 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, Indian ocean, Summer monsoon rainfall, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Moisture convergence, Climate model, 0105 earth and related environmental sciences, Mathematics
Abstract

International audience; The intraseasonal variability (ISV) is an intermittent phenomenon with variable perturbation patterns. To assess the robustness of the simulated ISV in climate models, it is thus interesting to consider the distribution of perturbation patterns rather than only one average pattern. To inspect this distribution, the authors first introduce a distance that measures the similarity between two patterns. The reproducibility (realism) of the simulated intraseasonal patterns is then defined as the distribution of distances between each pattern and the average simulated (observed) pattern. A good reproducibility is required to analyze the physical source of the simulated disturbances. The realism distribution is required to estimate the proportion of simulated events that have a perturbation pattern similar to observed patterns. The median value of this realism distribution is introduced as an ISV metric. The reproducibility and realism distributions are used to evaluate boreal summer ISV of precipitations over the Indian Ocean for 19 phase 3 of the Coupled Model Intercomparison Project (CMIP3) models. The 19 models are classified in increasing ISV metric order. In agreement with previous studies, the four best ISV metrics are obtained for models having a convective closure totally or partly based on the moisture convergence. Models with high metric values (poorly realistic) tend to give (i) poorly reproducible intraseasonal patterns, (ii) rainfall perturbations poorly organized at large scales, (iii) small day-to-day variability with overly red temporal spectra, and (iv) less accurate summer monsoon rainfall distribution. This confirms that the ISV is an important link in the seamless system that connects weather and climate. © 2010 American Meteorological Society.

Published
2010
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14. CIRENE Air-Sea Interactions in the Seychelles-Chagos Thermocline Ridge Region

Author

S. Kennan, Robert A. Weller, Alain Weill, Takeshi Izumo, Francis Marsac, O. Duteil, Jérôme Vialard, T. Fristedt, Sébastien Masson, Christophe Cassou, Erica L. Key, Jean-Philippe Duvel, Michael J. McPhaden, Pascale Bouruet-Aubertot, Laurence Eymard, Claude Basdevant, Brian Ward, Peter J. Minnett, Yves Dandonneau, Christophe E. Menkès, Denis Bourras, C. de Boyer Montégut, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), NOAA Pacific Marine Environmental Laboratory [Newport] (PMEL), National Oceanic and Atmospheric Administration (NOAA), Old Dominion University [Norfolk] (ODU), ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Woods Hole Oceanographic Institution (WHOI), University of Miami [Coral Gables], Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), CERFACS, Swedish Defence Research Agency [Stockholm] (FOI), Frontier Research Center for Global Change (FRCGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Thons tropicaux et écosystèmes pélagiques : taxies, interactions et stratégies d'exploitation (THETIS), National Institute of Water and Atmospheric Research [Wellington] (NIWA), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, southwest indian ocean, el nino, mixed layer, surface temperature, 01 natural sciences, dipole mode, tropical cyclones, 14. Life underwater, madden julian oscillation, Argo, 0105 earth and related environmental sciences, Monsoon of South Asia, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, intraseasonal variability, rainfall variability, 010505 oceanography, Madden–Julian oscillation, Sea surface temperature, Oceanography, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Ridge (meteorology), western pacific, Indian Ocean Dipole, Thermocline, Geology
Abstract

International audience; The Vasco–Cirene program explores how strong air–sea interactions promoted by the shallow thermocline and high sea surface temperature in the Seychelles–Chagos thermocline ridge results in marked variability at synoptic, intraseasonal, and interannual time scales. The Cirene oceanographic cruise collected oceanic, atmospheric, and air–sea flux observations in this region in January–February 2007. The contemporaneous Vasco field experiment complemented these measurements with balloon deployments from the Seychelles. Cirene also contributed to the development of the Indian Ocean observing system via deployment of a moor-ing and 12 Argo profilers.Unusual conditions prevailed in the Indian Ocean during January and February 2007, following the Indian Ocean dipole climate anomaly of late 2006. Cirene measurements show that the Seychelles–Chagos thermocline ridge had higher-than-usual heat content with subsurface anomalies up to 7°C. The ocean surface was warmer and fresher than average, and unusual eastward currents prevailed down to 800 m. These anomalous conditions had a major impact on tuna fishing in early 2007. Our dataset also sampled the genesis and maturation of Tropical Cyclone Dora, including high surface temperatures and a strong diurnal cycle before the cyclone, followed by a 1.5°C cooling over 10 days. Balloonborne instruments sampled the surface and boundary layer dynamics of Dora. We observed small-scale structures like dry-air layers in the atmosphere and diurnal warm layers in the near-surface ocean. The Cirene data will quantify the impact of these finescale features on the upper-ocean heat budget and atmospheric deep convection.

Published
2009
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15. The Aeroclipper: A New Device to Explore Convective Systems and Cyclones

Author

Claude Basdevant, André Vargas, Jérôme Vialard, Gilles Reverdin, Jean-Philippe Duvel, Hugo Bellenger, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL)

Subjects
Convection, Atmospheric Science, surface fluxes, 010504 meteorology & atmospheric sciences, Meteorology, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, 0207 environmental engineering, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, boundary layer, atmospheric research, arabian sea, 01 natural sciences, evaporation, New device, 020701 environmental engineering, enhancement, Trajectory (fluid mechanics), 0105 earth and related environmental sciences, temperature, parameterization, ocean, Atmospheric research, 13. Climate action, Climatology, Environmental science, Tropical cyclone, balloons
Abstract

International audience; Aeroclipper balloons, designed for taking measurements at the air-sea interface, can withstand extreme conditions encountered when they are drawn into tropical cyclones and then follow the eye trajectory.; Not Available

Published
2009
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16. Supplement to Cirene: Air-Sea Interactions in the Seychelles-Chagos Thermocline Ridge Region

Author

C. de Boyer Montégut, Sébastien Masson, S. Kennan, Yves Dandonneau, Alain Weill, Erica L. Key, Peter J. Minnett, Pascale Bouruet-Aubertot, Francis Marsac, Claude Basdevant, Jean-Philippe Duvel, Brian Ward, T. Fristedt, Christophe Cassou, Denis Bourras, Laurence Eymard, O. Duteil, Christophe E. Menkès, Robert A. Weller, Michael J. McPhaden, Takeshi Izumo, Jérôme Vialard, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), ESTER - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Thons tropicaux et écosystèmes pélagiques : taxies, interactions et stratégies d'exploitation (THETIS), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and CERFACS

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Madden–Julian oscillation, 010502 geochemistry & geophysics, 01 natural sciences, Sea surface temperature, Oceanography, 13. Climate action, Diurnal cycle, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Climatology, Ridge (meteorology), 14. Life underwater, Indian Ocean Dipole, Tropical cyclone, Thermocline, Geology, Argo, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

The Vasco—Cirene field experiment, in January—February 2007, targeted the Seychelles—Chagos thermocline ridge (SCTR) region, with the main purpose of investigating Madden—Julian Oscillation (MJO)-related SST events. The Validation of the Aeroclipper System under Convective Occurrences (Vasco) experiment (Duvel et al. 2009) and Cirene cruise were designed to provide complementary views of air—sea interaction in the SCTR region. While meteorological balloons were deployed from the Seychelles as a part of Vasco, the Research Vessel (R/V) Suroit was cruising the SCTR region as a part of Cirene. more: The Vasco—Cirene program explores how strong air—sea interactions promoted by the shallow thermocline and high sea surface temperature in the Seychelles—Chagos thermocline ridge results in marked variability at synoptic, intraseasonal, and interannual time scales. The Cirene oceanographic cruise collected oceanic, atmospheric, and air—sea flux observations in this region in January—February 2007. The contemporaneous Vasco field experiment complemented these measurements with balloon deployments from the Seychelles. Cirene also contributed to the development of the Indian Ocean observing system via deployment of a mooring and 12 Argo profilers. Unusual conditions prevailed in the Indian Ocean during January and February 2007, following the Indian Ocean dipole climate anomaly of late 2006. Cirene measurements show that the Seychelles—Chagos thermocline ridge had higher-than-usual heat content with subsurface anomalies up to 7°C. The ocean surface was warmer and fresher than average, and unusual eastward currents prevailed down to 800 m. These anomalous conditions had a major impact on tuna fishing in early 2007. Our dataset also sampled the genesis and maturation of Tropical Cyclone Dora, including high surface temperatures and a strong diurnal cycle before the cyclone, followed by a 1.5°C cooling over 10 days. Balloonborne instruments sampled the surface and boundary layer dynamics of Dora. We observed small-scale structures like dry-air layers in the atmosphere and diurnal warm layers in the near-surface ocean. The Cirene data will quantify the impact of these finescale features on the upper-ocean heat budget and atmospheric deep convection.

Published
2009
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17. Strong Indian Ocean sea surface temperature signals associated with the Madden-Julian Oscillation in late 2007 and early 2008

Author

Michael J. McPhaden, Jérôme Vialard, C. de Boyer Montégut, Jean-Philippe Duvel, Gregory R. Foltz, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), 010502 geochemistry & geophysics, Oceanography: Physical: Air/sea interactions (0312, 01 natural sciences, paific, layer heat balance, perturbations, Ekman transport, 14. Life underwater, 0105 earth and related environmental sciences, Buoy, Advection, Madden–Julian oscillation, Atmospheric Processes: Convective processes, prediction, Mooring, fluxes, 3339), Sea surface temperature, Geophysics, 13. Climate action, Climatology, General Earth and Planetary Sciences, Oceanography: Physical: Upper ocean and mixed layer processes, Thermocline, Geology
Abstract

A moored buoy was recently deployed at 8 degrees S, 67 degrees E in the shallow thermocline region of the Indian Ocean known as "Seychelles-Chagos Thermocline Ridge'' (SCTR), where the Madden Julian Oscillation (MJO) is associated with strong sea surface temperature (SST) variability. We use observations from this mooring to describe the oceanic signature of two MJOs between November 2007 and February 2008. The four-month average upper ocean heat balance was largely between heating by atmospheric forcing (2.0 +/- 0.3 degrees C/month) and a significant cooling by subsurface processes (-2.2 +/- 0.8 degrees C/month), consistent with climatological Ekman pumping in the region. The two MJO events resulted in strong intraseasonal SST variations (1.5 to 2 degrees C in similar to 20 days) in the SCTR. At the mooring site, atmospheric fluxes dominated the upper ocean heat balance at the MJO timescale, with the net surface heat flux into the ocean decreasing from an average 105 W m(-2) during suppressed phases to 15 W m(-2) during active phases of the MJO. It is difficult to establish if MJO-induced variations of subsurface processes also contributed to the cooling because of large uncertainty in this term. Lateral advection had no systematic fluctuations on MJO timescales, but cannot be neglected at the mooring site.

Published
2008
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18. Intraseasonal Convective Perturbations Related to the Seasonal March of the Indo-Pacific Monsoons

Author

Jean-Philippe Duvel, Hugo Bellenger, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
Convection, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Meteorological reanalysis, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, Indian ocean, Oceanography, 13. Climate action, Atmospheric convection, Climatology, BENGAL, 14. Life underwater, Bay, Indo-Pacific, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

The seasonal evolution of the 20–90-day intraseasonal variability (ISV) of the convection in the Indo-Pacific region presents intriguing features related to monsoon dynamics: (i) a sharp ISV maximum in May for the southern Bay of Bengal and in June for the eastern Arabian Sea, (ii) a maximum ISV over the west Pacific in July–September when the ISV over the northern Indian Ocean is weaker, (iii) a persistent ISV north of Australia from December to March, and (iv) a weak ISV over continental regions. The source of these behaviors is investigated from time series of satellite observations, meteorological reanalysis, and from an ocean mixed layer depth (MLD) climatology. For the northern Indian Ocean, sharp ISV maxima in May and June, when the MLD is still small (∼20–30 m), are related to an abrupt surface cooling associated with the setting of the monsoon low-level jet. The ISV of the convection is smaller over these regions during July–September when the MLD is deepened (∼60–70 m) by the monsoon low-level wind forcing. At this time, the low-level wind is weak over the west Pacific, the MLD is small, and the amplitude of the ISV remains large. North of Australia, and also over the south equatorial Indian Ocean, there is no particular reinforcement of the ISV near the onset. A weak low-level jet and a small MLD prevail during the whole monsoon season in good agreement with a more uniform ISV. These results support the hypothesis that a moderately shallow (∼20–30 m) ocean mixed layer is important for maintaining locally the ISV of the convection, when the conditions (e.g., SST, large-scale circulation) for such an ISV to exist are satisfied. The seasonal variability of the MLD, related in part to the monsoon low-level jet variability over the tropical oceans, thus gives a link between the seasonal march of monsoon circulations and the seasonal evolution of the ISV of the convection. This has implications for a better understanding of the origin of the ISV and for the predictability of its amplitude, especially near the monsoon onset date.

Published
2007
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19. Indo-Pacific Sea Surface Temperature Perturbations Associated with Intraseasonal Oscillations of Tropical Convection

Author

Jérôme Vialard, Jean-Philippe Duvel, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)

Subjects
Convection, Atmospheric Science, 010504 meteorology & atmospheric sciences, Mixed layer, western indian ocean, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], mixed layer, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Forcing (mathematics), Monsoon, 01 natural sciences, Atmospheric convection, Astrophysics::Solar and Stellar Astrophysics, 14. Life underwater, madden julian oscillation, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, model, 010505 oceanography, variability, bengal, Madden–Julian oscillation, fluxes, Sea surface temperature, 13. Climate action, Climatology, atmosphere, summer monsoon, warm pool, Indo-Pacific, Geology
Abstract

The intraseasonal variability (ISV; 20-90 days) of the SST is examined using 7 yr of data from the Tropical Rainfall Measuring Mission's (TRMM) Microwave Imager ( TMI). The ISV of the SST is larger in the summer hemisphere and in regions of relatively small ocean mixed layer depth (MLD). For these regions, the reddening of the SST spectrum in regard to the surface flux spectrum suggests that the ISV of the SST is mostly controlled by the integration of the local surface forcing by ocean mixed layer. However, the precise origin of large-scale organized perturbations of the SST also depends on region and season. Since the ISV of the convection is an intermittent phenomenon, the local mode analysis (LMA) technique is used to detect only the ensemble of intraseasonal events that are well organized at large scale. The LMA technique is further developed in this paper in order to perform multivariate analysis given patterns of SST and surface wind perturbations associated specifically with these intraseasonal events. During boreal winter, the basin- scale eastward propagation of the convective perturbation is present only over the Indian Ocean Basin. The intraseasonal SST response to convective perturbations is large and recurrent over thin mixed layer regions located north of Australia and in the Indian Ocean between 5 and 10 S. By contrast, there is little SST response in the western Pacific basin and no clear eastward propagation of the convective perturbation. During boreal summer, the SST response is large over regions with thin mixed layers located north of the Bay of Bengal, in the Arabian Sea, and in the China Sea. The northeastward propagation of the convective perturbation over the Bay of Bengal is associated with a standing oscillation of the SST and the surface wind between the equator and the northern part of the bay. In fact, many intraseasonal events mostly concern a single basin, suggesting that the interbasin organization is not a necessary condition for the existence of coupled intraseasonal perturbations of the convection. The perturbation of the surface wind tends to be larger to the west of the large-scale convective perturbation (like for a Gill- type dynamical response). For eastward propagating perturbations, the cooling due to the reinforcement of the wind (i. e., surface turbulent heat flux) thus generally lags the radiative cooling due to the reduction of the surface solar flux by the convective cloudiness. This large-scale Gill-type response of the surface wind also cools the surface to the west of the basin (northwest Arabian Sea and northwest Pacific Ocean), even if the convection is locally weak. An intriguing result is a frequently occurring small delay between the maximum surface wind and the minimum SST. Different explanations are invoked, like a rapid surface cooling due to the vanishing of an ocean warm layer (diurnal surface warming due to solar radiation in low wind conditions) as soon as the wind increases.

Published
2007
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20. Ocean Mixed Layer Temperature Variations Induced by Intraseasonal Convective Perturbations over the Indian Ocean

Author

Rémy Roca, Jérôme Vialard, Jean-Philippe Duvel, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
TEMPERATURE DE SURFACE, Atmospheric Science, Mixed layer, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Ocean current, Equator, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Ocean general circulation model, VARIATION INTERANNUELLE, MODELE, Sea surface temperature, La Niña, 13. Climate action, Climatology, ANOMALIE DE TEMPERATURE, Ekman transport, 14. Life underwater, INTERACTION OCEAN ATMOSPHERE, Thermocline, Geology, ANALYSE DE DONNEES
Abstract

In situ and satellite observations reveal that the tropical intraseasonal oscillation is occasionally associated with large variations in sea surface temperature (SST). The purpose of this paper is to find the physical origin of such strong SST perturbations (up to 3 K) over the Indian Ocean by examining two intraseasonal events in January and March 1999. Analysis of SST data from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and from drifting buoys reveals that these two intraseasonal events deeply modify the SST field between the equator and 108S, while the surface flux perturbation extends over a wide area of the tropical Indian Ocean. Forced ocean general circulation model (OGCM) simulations are successful in reproducing the spatial patterns of this intraseasonal SST variability albeit with a weaker amplitude. The weaker amplitude given by the OGCM is partly related to the absence of warm-layer formation in the model. The model simulation reveals that the background oceanic subsurface structure explains the observed latitudinal distribution of the

Published
2004
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21. Role of non-linear oceanic processes in the response to westerly wind events: new implications for the 1997 El Niño onset

Author

Jean-Philippe Duvel, Matthieu Lengaigne, Maurice Imbard, Pascale Delecluse, Jean-Philippe Boulanger, Gurvan Madec, Sébastien Masson, Edmée Durand, Christophe E. Menkès, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
010504 meteorology & atmospheric sciences, 010505 oceanography, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 01 natural sciences, Pacific ocean, symbols.namesake, Geophysics, El Niño, 13. Climate action, Downwelling, Climatology, Zonal flow, symbols, General Earth and Planetary Sciences, 14. Life underwater, Kelvin wave, Geology, 0105 earth and related environmental sciences
Abstract

In March 1997, a strong westerly wind event (WWE) occurred in the western equatorial Pacific prior to the 1997-1998 E1 Nifio event. It produced downwelling Kelvin waves that interacted non linearly with the surface temperature, salinity and zonal current fronts located at the eastern edge of the warm-fresh pool (EEWP). This non-linear interaction locally increased zonal currents by a factor of three compared to a theoretical linear response, and advected the EEWP at an unexpected rate (-l m/s) to which the ocean-atmosphere coupled system may have been responding rapidly to trigger E1 Nino conditions.

Published
2001
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