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242 results on '"Msadek, Rym"'

7. Impacts of Atlantic multidecadal variability on the tropical Pacific: a multi-model study

Author

Ruprich-Robert, Yohan, Moreno-Chamarro, Eduardo, Levine, Xavier, Bellucci, Alessio, Cassou, Christophe, Castruccio, Frederic, Davini, Paolo, Eade, Rosie, Gastineau, Guillaume, Hermanson, Leon, Hodson, Dan, Lohmann, Katja, Lopez-Parages, Jorge, Monerie, Paul-Arthur, Nicolì, Dario, Qasmi, Said, Roberts, Christopher D., Sanchez-Gomez, Emilia, Danabasoglu, Gokhan, Dunstone, Nick, Martin-Rey, Marta, Msadek, Rym, Robson, Jon, Smith, Doug, and Tourigny, Etienne

Published
2021
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18. Managing living marine resources in a dynamic environment: The role of seasonal to decadal climate forecasts

Author

Tommasi, Desiree, Stock, Charles A., Hobday, Alistair J., Methot, Rick, Kaplan, Isaac C., Eveson, J. Paige, Holsman, Kirstin, Miller, Timothy J., Gaichas, Sarah, Gehlen, Marion, Pershing, Andrew, Vecchi, Gabriel A., Msadek, Rym, Delworth, Tom, Eakin, C. Mark, Haltuch, Melissa A., Séférian, Roland, Spillman, Claire M., Hartog, Jason R., Siedlecki, Samantha, Samhouri, Jameal F., Muhling, Barbara, Asch, Rebecca G., Pinsky, Malin L., Saba, Vincent S., Kapnick, Sarah B., Gaitan, Carlos F., Rykaczewski, Ryan R., Alexander, Michael A., Xue, Yan, Pegion, Kathleen V., Lynch, Patrick, Payne, Mark R., Kristiansen, Trond, Lehodey, Patrick, and Werner, Francisco E.

Published
2017
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22. Intercomparison of the Arctic sea ice cover in global ocean–sea ice reanalyses from the ORA-IP project

Author

Chevallier, Matthieu, Smith, Gregory C., Dupont, Frédéric, Lemieux, Jean-François, Forget, Gael, Fujii, Yosuke, Hernandez, Fabrice, Msadek, Rym, Peterson, K. Andrew, Storto, Andrea, Toyoda, Takahiro, Valdivieso, Maria, Vernieres, Guillaume, Zuo, Hao, Balmaseda, Magdalena, Chang, You-Soon, Ferry, Nicolas, Garric, Gilles, Haines, Keith, Keeley, Sarah, Kovach, Robin M., Kuragano, Tsurane, Masina, Simona, Tang, Yongming, Tsujino, Hiroyuki, and Wang, Xiaochun

Published
2017
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29. DECADAL CLIMATE PREDICTION : An Update from the Trenches

Author

Meehl, Gerald A., Goddard, Lisa, Boer, George, Burgman, Robert, Branstator, Grant, Cassou, Christophe, Corti, Susanna, Danabasoglu, Gokhan, Doblas-Reyes, Francisco, Hawkins, Ed, Karspeck, Alicia, Kimoto, Masahide, Kumar, Arun, Matei, Daniela, Mignot, Juliette, Msadek, Rym, Navarra, Antonio, Pohlmann, Holger, Rienecker, Michele, Rosati, Tony, Schneider, Edwin, Smith, Doug, Sutton, Rowan, Teng, Haiyan, van Oldenborgh, Geert Jan, Vecchi, Gabriel, and Yeager, Stephen

Published
2014

31. Geostrophic and Mesoscale Eddy Contributions to the Atlantic Meridional Overturning Circulation Decline under CO 2 Increase in the GFDL CM2-O Model Suite.

Author

Fortin, Anne-Sophie, Dufour, Carolina O., Merlis, Timothy M., and Msadek, Rym

Subjects
ATLANTIC meridional overturning circulation, MESOSCALE eddies, ATMOSPHERIC carbon dioxide, CARBON dioxide, ATMOSPHERIC models
Abstract

The pattern and magnitude of the Atlantic meridional overturning circulation (AMOC) in response to an increase in atmospheric carbon dioxide (CO2) concentration greatly differ across climate models in particular due to differences in the representation of oceanic processes. Here, we investigate the response of the AMOC to an idealized climate change scenario, along with the drivers of this response, in the three configurations of a coupled climate model suite with varying resolutions in the ocean (1°, 0.25°, 0.10°). In response to the CO2 increase, the AMOC shows a reduction of similar magnitude in the low and high resolutions, while a muted response is found in the medium resolution. A decomposition of the AMOC into its geostrophic and residual components reveals that most of the AMOC reduction is due to a weakening of the geostrophic streamfunction driven by temperature anomalies, partly opposed by a strengthening of the geostrophic streamfunction driven by salinity anomalies. Changes in the AMOC due to the mesoscale eddy streamfunction contribute to 13% and 17% of the AMOC decline in the low and high resolutions, respectively, but induce very little change in the medium resolution. The similar response of the AMOC strength in the low and high resolutions hides important differences in the contribution and pattern of the geostrophic and eddy streamfunctions. The lack of sensitivity of the medium resolution to the CO2 forcing is due to a weak connection between the deep water formation regions in the northern subpolar gyre and the Deep Western Boundary Current. Significance Statement: The Atlantic meridional overturning circulation (AMOC) is a major system of ocean currents in the Atlantic that contributes to shaping the climate at regional and global scales, notably through the transport of heat from the low to the high latitudes. A major slowdown of the AMOC over the twenty-first century is predicted by current climate models in response to increasing greenhouse gases. Yet, the magnitude and timing of this slowdown are uncertain. The purpose of this study is to investigate the expected weakening of the AMOC using state-of-the-art numerical climate models that include higher resolutions than typically used in climate change assessments. Our results provide insights into the mechanisms driving the weakening of the AMOC and into differences arising from model resolutions. [ABSTRACT FROM AUTHOR]

Published
2023
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32. Consistent but more intense atmospheric circulation response to Arctic sea ice loss in CMIP6 experiments compared to PAMIP experiments.

Author

Delhaye, Steve, Msadek, Rym, Fichefet, Thierry, Massonnet, François, and Terray, Laurent

Subjects
*ATMOSPHERIC circulation, *SEA ice, *NORTH Atlantic oscillation, *POLAR vortex, *CLIMATE feedbacks, *ATMOSPHERIC models
Abstract

The atmospheric circulation response to Arctic sea ice loss may differ depending on the region of sea ice loss but also on the methodology used to study this impact. Examining the different possible atmospheric circulation responses to sea ice loss is essential, as the Arctic sea ice is not melting uniformly. In this study, we examine the atmospheric response in winter to regional sea ice loss using two different approaches across seven climate models. The sea ice anomaly areas are the pan-Arctic, the Barents-Kara Seas only, and the Sea of Okhotsk only. The first approach involves sensitivity experiments performed within the Polar Amplification Model Intercomparison Project (PAMIP), while the second approach entails a composite analysis in long pre-industrial control simulations from CMIP6. Our results reveal that both approaches lead to consistent atmospheric circulation responses to pan-Arctic sea ice loss, characterized by a negative phase in the North Atlantic Oscillation and a weakening of the stratospheric polar vortex. Similar responses to BK sea ice loss are simulated, albeit with more spread in the PAMIP experiments. The responses to Okhotsk sea ice loss differ and are uncertain in both approaches. Furthermore, larger changes are detected in the composite analysis than in the sensitivity experiments, likely due to a different background state and the presence of confounding factors in the composite analysis. We also find that the atmosphere-ocean coupling does not imply larger circulation changes or a better representation of the eddy momentum feedback in the climate response. These results highlight that sea ice loss in sensitivity experiments yields a weaker atmospheric circulation response compared to the pre-industrial simulations in CMIP6 where the sea ice loss is governed by internal climate variability. A quantification of the role played by factors related to sea ice loss that amplifies the response should be further investigated. [ABSTRACT FROM AUTHOR]

Published
2023
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36. Robust but weak winter atmospheric circulation response to future Arctic sea ice loss

Author

Smith, D. M., Eade, R., Andrews, M. B., Ayres, H., Clark, A., Chripko, S., Deser, Clara, Dunstone, N. J., García-Serrano, Javier, Gastineau, G., Graff, L. S., Hardiman, S. C., He, B., Hermanson, L., Jung, Thomas, Knight, J., Levine, X., Magnusdottir, G., Manzini, E., Matei, Daniela, Mori, M., Msadek, Rym, Ortega, P., Peings, Y., Scaife, A. A., Screen, J. A., Seabrook, M., Semmler, Tido, Sigmond, M., Streffing, Jan, Sun, L., Walsh, A., Smith, D. M., Eade, R., Andrews, M. B., Ayres, H., Clark, A., Chripko, S., Deser, Clara, Dunstone, N. J., García-Serrano, Javier, Gastineau, G., Graff, L. S., Hardiman, S. C., He, B., Hermanson, L., Jung, Thomas, Knight, J., Levine, X., Magnusdottir, G., Manzini, E., Matei, Daniela, Mori, M., Msadek, Rym, Ortega, P., Peings, Y., Scaife, A. A., Screen, J. A., Seabrook, M., Semmler, Tido, Sigmond, M., Streffing, Jan, Sun, L., and Walsh, A.

Abstract

The possibility that Arctic sea ice loss weakens mid-latitude westerlies, promoting more severe cold winters, has sparked more than a decade of scientific debate, with apparent support from observations but inconclusive modelling evidence. Here we show that sixteen models contributing to the Polar Amplification Model Intercomparison Project simulate a weakening of mid-latitude westerlies in response to projected Arctic sea ice loss. We develop an emergent constraint based on eddy feedback, which is 1.2 to 3 times too weak in the models, suggesting that the real-world weakening lies towards the higher end of the model simulations. Still, the modelled response to Arctic sea ice loss is weak: the North Atlantic Oscillation response is similar in magnitude and offsets the projected response to increased greenhouse gases, but would only account for around 10% of variations in individual years. We further find that relationships between Arctic sea ice and atmospheric circulation have weakened recently in observations and are no longer inconsistent with those in models.

Published
2022

37. Summertime changes in climate extremes over the peripheral Arctic regions after a sudden sea ice retreat

Author

UCL - SST/ELI/ELIC - Earth & Climate, Delhaye, Steve, Fichefet, Thierry, Massonnet, François, Docquier, David, Msadek, Rym, Chripko, Svenya, Roberts, Christopher, Keeley, Sarah, Retish,Senan, UCL - SST/ELI/ELIC - Earth & Climate, Delhaye, Steve, Fichefet, Thierry, Massonnet, François, Docquier, David, Msadek, Rym, Chripko, Svenya, Roberts, Christopher, Keeley, Sarah, and Retish,Senan

Abstract

The retreat of Arctic sea ice is frequently considered to be a possible driver of changes in climate extremes in the Arctic and possibly down to mid-latitudes. However, it remains unclear how the atmosphere will respond to a near-total retreat of summer Arctic sea ice, a reality that might occur in the foreseeable future. This study explores this question by conducting sensitivity experiments with two global coupled climate models run at two different horizontal resolutions to investigate the change in temperature and precipitation extremes during summer over peripheral Arctic regions following a sudden reduction in summer Arctic sea ice cover. An increase in frequency and persistence of maximum surface air temperature is found in all peripheral Arctic regions during the summer, when sea ice loss occurs. For each 1×106 km2 of Arctic sea ice extent reduction, the absolute frequency of days exceeding the surface air temperature of the climatological 90th percentile increases by ∼ 4 % over the Svalbard area, and the duration of warm spells increases by ∼ 1 d per month over the same region. Furthermore, we find that the 10th percentile of surface daily air temperature increases more than the 90th percentile, leading to a weakened diurnal cycle of surface air temperature. Finally, an increase in extreme precipitation, which is less robust than the increase in extreme temperatures, is found in all regions in summer. These findings suggest that a sudden retreat of summer Arctic sea ice clearly impacts the extremes in maximum surface air temperature and precipitation over the peripheral Arctic regions with the largest influence over inhabited islands such as Svalbard or northern Canada. Nonetheless, even with a large sea ice reduction in regions close to the North Pole, the local precipitation response is relatively small compared to internal climate variability.

Published
2022

42. Erratum to: Intercomparison of the Arctic sea ice cover in global ocean–sea ice reanalyses from the ORA-IP project

Author

Chevallier, Matthieu, Smith, Gregory C., Dupont, Frédéric, Lemieux, Jean-François, Forget, Gael, Fujii, Yosuke, Hernandez, Fabrice, Msadek, Rym, Peterson, K. Andrew, Storto, Andrea, Toyoda, Takahiro, Valdivieso, Maria, Vernieres, Guillaume, Zuo, Hao, Balmaseda, Magdalena, Chang, You-Soon, Ferry, Nicolas, Garric, Gilles, Haines, Keith, Keeley, Sarah, Kovach, Robin M., Kuragano, Tsurane, Masina, Simona, Tang, Yongming, Tsujino, Hiroyuki, and Wang, Xiaochun

Published
2017
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45. Atmospheric response to Arctic sea ice decline: results from PAMIP experiments

Author

Msadek Rym, Chripko Svenya, Sanchez-Gomez Emilia, and Terray Laurent

Subjects
Northern Hemisphere atmospheric circulation, Arctic sea ice, 2 degree warming
Abstract

We analyze the Northern Hemisphere atmospheric response to Arctic sea ice decline in the CNRM-CM6 model (130km resolution, 91 vertical levels) using atmosphere-only experiments that follow the PAMIP protocol described in Smith et al. (2019). The high-top atmospheric component of CNRM-CM6 is forced by the same pattern of SST but different idealized patterns of sea ice that correspond to i) pre-industrial conditions (PI), ii) present day conditions (PD), and iii) future conditions (FUT) associated with a 2C warming with respect to i). Each experiment is run for 14 months starting in April, using at least 100 members. We focus on the cold season response (October to March) and describe the atmospheric response for different sea ice forcings applied either in to whole Arctic or to specific regions of the Arctic.

Published
2021
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46. Impacts of Atlantic multidecadal variability on the tropical Pacific: a multi-model study

Author

European Commission, National Science Foundation (US), National Oceanic and Atmospheric Administration (US), Agencia Estatal de Investigación (España), Ruprich-Robert, Yohan, Moreno-Chamarro, E., Levine, Xavier, Bellucci, Alessio, Cassou, Christophe, Castruccio, Frederic, Davini, Paolo, Eade, Rosie, Gastineau, Guillaume, Hermanson, Leon, Hodson, Dan, Lohmann, Katja, López-Parages, Jorge, Monerie, P.-A., Nicolì, Dario, Qasmi, Said, Roberts, Christopher D., Sánchez-Gómez, E., Danabasoglu, Gokhan, Dunstone, Nick J., Martín-Rey, Marta, Msadek, Rym, Robson, Jon, Smith, Doug, Tourigny, Etienne, European Commission, National Science Foundation (US), National Oceanic and Atmospheric Administration (US), Agencia Estatal de Investigación (España), Ruprich-Robert, Yohan, Moreno-Chamarro, E., Levine, Xavier, Bellucci, Alessio, Cassou, Christophe, Castruccio, Frederic, Davini, Paolo, Eade, Rosie, Gastineau, Guillaume, Hermanson, Leon, Hodson, Dan, Lohmann, Katja, López-Parages, Jorge, Monerie, P.-A., Nicolì, Dario, Qasmi, Said, Roberts, Christopher D., Sánchez-Gómez, E., Danabasoglu, Gokhan, Dunstone, Nick J., Martín-Rey, Marta, Msadek, Rym, Robson, Jon, Smith, Doug, and Tourigny, Etienne

Abstract

Atlantic multidecadal variability (AMV) has been linked to the observed slowdown of global warming over 1998–2012 through its impact on the tropical Pacific. Given the global importance of tropical Pacific variability, better understanding this Atlantic–Pacific teleconnection is key for improving climate predictions, but the robustness and strength of this link are uncertain. Analyzing a multi-model set of sensitivity experiments, we find that models differ by a factor of 10 in simulating the amplitude of the Equatorial Pacific cooling response to observed AMV warming. The inter-model spread is mainly driven by different amounts of moist static energy injection from the tropical Atlantic surface into the upper troposphere. We reduce this inter-model uncertainty by analytically correcting models for their mean precipitation biases and we quantify that, following an observed 0.26 °C AMV warming, the equatorial Pacific cools by 0.11 °C with an inter-model standard deviation of 0.03 °C

Published
2021

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