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2. Drivers of Precipitation Change : An Energetic Understanding

Author

Richardson, T. B., Forster, P. M., Andrews, T., Boucher, O., Faluvegi, G., Fläschner, D., Hodnebrog, Ø., Kasoar, M., Kirkevåg, A., Lamarque, J.-F., Myhre, G., Olivié, D., Samset, B. H., Shawki, D., Shindell, D., Takemura, T., and Voulgarakis, A.

Published
2018

4. Future impact of traffic emissions on atmospheric ozone and OH based on two scenarios

Author

Hodnebrog, O., Berntsen, T. K, Dessens, O., Gauss, M., Grewe, V., Isaksen, I. S. A, Koffi, B., Myhre, G., Olivie, D., Prather, M. J, Stordal, F., Szopa, S., Tang, Q., van Velthoven, P., and Williams, J. E

Abstract

The future impact of traffic emissions on atmospheric ozone and OH has been investigated separately for the three sectors AIRcraft, maritime SHIPping and ROAD traffic. To reduce uncertainties we present results from an ensemble of six different atmospheric chemistry models, each simulating the atmospheric chemical composition in a possible high emission scenario (A1B), and with emissions from each transport sector reduced by 5% to estimate sensitivities. Our results are compared with optimistic future emission scenarios (B1 and B1 ACARE), presented in a companion paper, and with the recent past (year 2000). Present-day activity indicates that anthropogenic emissions so far evolve closer to A1B than the B1 scenario. As a response to expected changes in emissions, AIR and SHIP will have increased impacts on atmospheric O3 and OH in the future while the impact of ROAD traffic will decrease substantially as a result of technological improvements. In 2050, maximum aircraft-induced O3 occurs near 80° N in the UTLS region and could reach 9 ppbv in the zonal mean during summer. Emissions from ship traffic have their largest O3 impact in the maritime boundary layer with a maximum of 6 ppbv over the North Atlantic Ocean during summer in 2050. The O3 impact of road traffic emissions in the lower troposphere peaks at 3 ppbv over the Arabian Peninsula, much lower than the impact in 2000. Radiative forcing (RF) calculations show that the net effect of AIR, SHIP and ROAD combined will change from a marginal cooling of −0.44 ± 13 mW m−2 in 2000 to a relatively strong cooling of −32 ± 9.3 (B1) or −32 ± 18 mW m−2 (A1B) in 2050, when taking into account RF due to changes in O3, CH4 and CH4-induced O3. This is caused both by the enhanced negative net RF from SHIP, which will change from −19 ± 5.3 mW m−2 in 2000 to −31 ± 4.8 (B1) or −40 ± 9 mW m−2 (A1B) in 2050, and from reduced O3 warming from ROAD, which is likely to turn from a positive net RF of 12 ± 8.5 mW m−2 in 2000 to a slightly negative net RF of −3.1 ± 2.2 (B1) or −3.1 ± 3.4 (A1B) mW m−2 in the middle of this century. The negative net RF from ROAD is temporary and induced by the strong decline in ROAD emissions prior to 2050, which only affects the methane cooling term due to the longer lifetime of CH4 compared to O3. The O3 RF from AIR in 2050 is strongly dependent on scenario and ranges from 19 ± 6.8 (B1 ACARE) to 61 ± 14 mW m−2 (A1B). There is also a considerable span in the net RF from AIR in 2050, ranging from −0.54 ± 4.6 (B1 ACARE) to 12 ± 11 (A1B) mW m−2 compared to 6.6 ± 2.2 mW m−2 in 2000.

Published
2012

5. Future impact of non-land based traffic emissions on atmospheric ozone and OH - an optimistic scenario and a possible mitigation strategy

Author

Hodnebrog, O., Berntsen, T. K, Dessens, O., Gauss, M., Grewe, V., Isaksen, I. S. A, Koffi, B., Myhre, G., Olivie, D., Prather, M. J, Pyle, J. A, Stordal, F., Szopa, S., Tang, Q., van Velthoven, P., Williams, J. E, and Odemark, K.

Subjects
atmospheric chemistry, atmospheric modeling, boundary layer, chemical composition, ozone, radiative forcing, traffic emission
Abstract

The impact of future emissions from aviation and shipping on the atmospheric chemical composition has been estimated using an ensemble of six different atmospheric chemistry models. This study considers an optimistic emission scenario (B1) taking into account e.g. rapid introduction of clean and resource-efficient technologies, and a mitigation option for the aircraft sector (B1 ACARE), assuming further technological improvements. Results from sensitivity simulations, where emissions from each of the transport sectors were reduced by 5%, show that emissions from both aircraft and shipping will have a larger impact on atmospheric ozone and OH in near future (2025; B1) and for longer time horizons (2050; B1) compared to recent time (2000). However, the ozone and OH impact from aircraft can be reduced substantially in 2050 if the technological improvements considered in the B1 ACARE will be achieved. Shipping emissions have the largest impact in the marine boundary layer and their ozone contribution may exceed 4 ppbv (when scaling the response of the 5% emission perturbation to 100% by applying a factor 20) over the North Atlantic Ocean in the future (2050; B1) during northern summer (July). In the zonal mean, ship-induced ozone relative to the background levels may exceed 12% near the surface. Corresponding numbers for OH are 6.0 × 105 molecules cm−3 and 30%, respectively. This large impact on OH from shipping leads to a relative methane lifetime reduction of 3.92 (±0.48) on the global average in 2050 B1 (ensemble mean CH4 lifetime is 8.0 (±1.0) yr), compared to 3.68 (±0.47)% in 2000. Aircraft emissions have about 4 times higher ozone enhancement efficiency (ozone molecules enhanced relative to NOx molecules emitted) than shipping emissions, and the maximum impact is found in the UTLS region. Zonal mean aircraft-induced ozone could reach up to 5 ppbv at northern mid- and high latitudes during future summer (July 2050; B1), while the relative impact peaks during northern winter (January) with a contribution of 4.2%. Although the aviation-induced impact on OH is lower than for shipping, it still causes a reduction in the relative methane lifetime of 1.68 (±0.38)% in 2050 B1. However, for B1 ACARE the perturbation is reduced to 1.17 (±0.28)%, which is lower than the year 2000 estimate of 1.30 (±0.30)%. Based on the fully scaled perturbations we calculate net radiative forcings from the six models taking into account ozone, methane (including stratospheric water vapour), and methane-induced ozone changes. For the B1 scenario, shipping leads to a net cooling with radiative forcings of −28.0 (±5.1) and −30.8 (±4.8) mW m−2 in 2025 and 2050, respectively, due to the large impact on OH and, thereby, methane lifetime reductions. Corresponding values for the aviation sector shows a net warming effect with 3.8 (±6.1) and 1.9 (±6.3) mW m−2, respectively, but with a small net cooling of -0.6 (±4.6) mW m−2 for B1 ACARE in 2050.

Published
2011

7. The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY

Author

Hoor, P., Borken-Kleefeld, J., Caro, D., Dessens, O., Endresen, O., Gauss, M., Grewe, V., Hauglustaine, D., Isaksen, I. S. A, Jockel, P., Lelieveld, J., Myhre, G., Meijer, E., Olivie, D., Prather, M., Schnadt Poberaj, C., Shine, K. P, Staehelin, J., Tang, Q., van Aardenne, J., van Velthoven, P., and Sausen, R.

Subjects
aircraft nox emissions, general-circulation model, chemical-transport model, tropospheric ozone, nitrogen-oxides, heterogeneous chemistry, nonmethane hydrocarbons, technical note, climate model, mozaic data
Abstract

To estimate the impact of emissions by road, aircraft and ship traffic on ozone and OH in the present-day atmosphere six different atmospheric chemistry models have been used. Based on newly developed global emission inventories for road, ship and aircraft emission data sets each model performed sensitivity simulations reducing the emissions of each transport sector by 5%. The model results indicate that on global annual average lower tropospheric ozone responds most sensitive to ship emissions (50.6%±10.9% of the total traffic induced perturbation), followed by road (36.7%±9.3%) and aircraft exhausts (12.7%±2.9%), respectively. In the northern upper troposphere between 200–300 hPa at 30–60° N the maximum impact from road and ship are 93% and 73% of the maximum effect of aircraft, respectively. The latter is 0.185 ppbv for ozone (for the 5% case) or 3.69 ppbv when scaling to 100%. On the global average the impact of road even dominates in the UTLS-region. The sensitivity of ozone formation per NOx molecule emitted is highest for aircraft exhausts. The local maximum effect of the summed traffic emissions on the ozone column predicted by the models is 0.2 DU and occurs over the northern subtropical Atlantic extending to central Europe. Below 800 hPa both ozone and OH respond most sensitively to ship emissions in the marine lower troposphere over the Atlantic. Based on the 5% perturbation the effect on ozone can exceed 0.6% close to the marine surface (global zonal mean) which is 80% of the total traffic induced ozone perturbation. In the southern hemisphere ship emissions contribute relatively strongly to the total ozone perturbation by 60%–80% throughout the year. Methane lifetime changes against OH are affected strongest by ship emissions up to 0.21 (± 0.05)%, followed by road (0.08 (±0.01)%) and air traffic (0.05 (± 0.02)%).Based on the full scale ozone and methane perturbations positive radiative forcings were calculated for road emissions (7.3±6.2 mWm−2) and for aviation (2.9±2.3 mWm−2). Ship induced methane lifetime changes dominate over the ozone forcing and therefore lead to a net negative forcing (−25.5±13.2 mWm−2).

Published
2009

9. Sensible Heat Has Significantly Affected the Global Hydrological Cycle Over the Historical Period

Author

Myhre, G, Samset, B. H, Hodnebrog, Ø, Andrews, T, Boucher, O, Faluvegi, G, Fläschner, D, Forster, P.M, Kasoar, M, Kharin, V, Kirkevåg, A, Lamarque, J.-F, Olivie, D, Richardson, T.B, Shawki, D, Shindell, D, Shine, K.P, Stjern, C.W, Takemura, T, and Voulgarakis, A

Subjects
Meteorology And Climatology
Abstract

Globally, latent heating associated with a change in precipitation is balanced by changes to atmospheric radiative cooling and sensible heat fluxes. Both components can be altered by climate forcing mechanisms and through climate feedbacks, but the impacts of climate forcing and feedbacks on sensible heat fluxes have received much less attention. Here we show, using a range of climate modelling results, that changes in sensible heat are the dominant contributor to the present global-mean precipitation change since preindustrial time, because the radiative impact of forcings and feedbacks approximately compensate. The model results show a dissimilar influence on sensible heat and precipitation from various drivers of climate change. Due to its strong atmospheric absorption, black carbon is found to influence the sensible heat very differently compared to other aerosols and greenhouse gases. Our results indicate that this is likely caused by differences in the impact on the lower tropospheric stability.

Published
2018
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12. Weak Hydrological Sensitivity to Temperature Change over Land, Independent of Climate Forcing

Author

Samset, B. H, Myhre, G, Forster, P. M, Hodnebrog, O, Andrews, T, Boucher, O, Faluvegi, G, Flaeschner, D, Kasoar, M, Kharin, V, Kirkevag, A, Lamarque, J.-F, Olivie, D, Richardson, T. B, Shindell, D, Takemura, T, and Voulgarakis, A

Subjects
Meteorology And Climatology
Abstract

We present the global and regional hydrological sensitivity (HS) to surface temperature changes, for perturbations to CO2, CH4, sulfate and black carbon concentrations, and solar irradiance. Based on results from ten climate models, we show how modeled global mean precipitation increases by 2-3% per kelvin of global mean surface warming, independent of driver, when the effects of rapid adjustments are removed. Previously reported differences in response between drivers are therefore mainly ascribable to rapid atmospheric adjustment processes. All models show a sharp contrast in behavior over land and over ocean, with a strong surface temperature-driven (slow) ocean HS of 3-5%/K, while the slow land HS is only 0-2%/K. Separating the response into convective and large-scale cloud processes, we find larger inter-model differences, in particular over land regions. Large-scale precipitation changes are most relevant at high latitudes, while the equatorial HS is dominated by convective precipitation changes. Black carbon stands out as the driver with the largest inter-model slow HS variability, and also the strongest contrast between a weak land and strong sea response. We identify a particular need for model investigations and observational constraints on convective precipitation in the Arctic, and large-scale precipitation around the Equator.

Published
2018
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14. Drivers of Precipitation Change: An Energetic Understanding

Author

Richardson, T. B, Forster, P. M, Andrews, B, Boucher, O, Faluvegi, G, Flashner, D, Hodnebrog, O, Kasoar, M, Kirkevag, A, Lamarque, J.-F, Myhre, G, Olivie, D, B. H. Samset, Shawki, D, Shindell, D, Takemure, T, and Voulgarakis, A

Subjects
Meteorology And Climatology
Abstract

The response of the hydrological cycle to climate forcings can be understood within the atmospheric energy budget framework. In this study precipitation and energy budget responses to five forcing agents are analyzed using 10 climate models from the Precipitation Driver Response Model Intercomparison Project (PDRMIP). Precipitation changes are split into a forcing-dependent fast response and a temperature-driven hydrological sensitivity. Globally, when normalized by top-of-atmosphere (TOA) forcing, fast precipitation changes are most sensitive to strongly absorbing drivers (CO2, black carbon). However, over land fast precipitation changes are most sensitive to weakly absorbing drivers (sulfate, solar) and are linked to rapid circulation changes. Despite this, land-mean fast responses to CO2 and black carbon exhibit more intermodel spread. Globally, the hydrological sensitivity is consistent across forcings, mainly associated with increased longwave cooling, which is highly correlated with intermodel spread. The land-mean hydrological sensitivity is weaker, consistent with limited moisture availability. The PDRMIP results are used to construct a simple model for land-mean and sea-mean precipitation change based on sea surface temperature change and TOA forcing. The model matches well with CMIP5 ensemble mean historical and future projections, and is used to understand the contributions of different drivers. During the twentieth century, temperature-driven intensification of land-mean precipitation has been masked by fast precipitation responses to anthropogenic sulfate and volcanic forcing, consistent with the small observed trend. However, as projected sulfate forcing decreases, and warming continues, land-mean precipitation is expected to increase more rapidly, and may become clearly observable by the mid-twenty-first century.

Published
2017
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15. Evaluation of Observed and Modelled Aerosol Lifetimes Using Radioactive Tracers of Opportunity and an Ensemble of 19 Global Models

Author

Kristiansen, N. I, Stohl, A, Olivie, D. J. L, Croft, B, Sovde, O. A, Klein, H, Christoudias, T, Kunkel, D, Leadbetter, S. J, Lee, Y. H, Zhang, K, Tsigaridis, K, Bauer, S. E, Faluvegi, G. S, and Shindell, D

Subjects
Meteorology And Climatology
Abstract

Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (Cs-137) and xenon-133 (Xe-133) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their available aerosol surface area. Cs-137 size distribution measurements taken close to the power plant suggested that accumulation mode (AM) sulfate aerosols were the main carriers of cesium. Hence, Cs-137 can be used as a proxy tracer for the AM sulfate aerosol's fate in the atmosphere. In contrast, the noble gas Xe-133 behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of Cs-137that were assigned to an aerosol tracer with each model's default properties of AM sulfate, and Xe-133 emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulfate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled Cs-137and Xe-133 concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime e, calculated from station measurement data taken between 2 and 9 weeks after the start of the emissions, is 14.3 days (95% confidence interval 13.1-15.7 days). The equivalent modelled e lifetimes have a large spread, varying between 4.8 and 26.7 days with a model median of 9.42.3 days, indicating too fast a removal in most models. Because sufficient measurement data were only available from about 2 weeks after the release, the estimated lifetimes apply to aerosols that have undergone long-range transport, i.e. not for freshly emitted aerosol. However, modelled instantaneous lifetimes show that the initial removal in the first 2 weeks was quicker (lifetimes between 1 and 5 days) due to the emissions occurring at low altitudes and co-location of the fresh plume with strong precipitation. Deviations between measured and modelled aerosol lifetimes are largest for the northernmost stations and at later time periods, suggesting that models do not transport enough of the aerosol towards the Arctic. The models underestimate passive tracer (Xe-133) concentrations in the Arctic as well but to a smaller extent than for the aerosol (Cs-137) tracer. This indicates that in addition to too fast an aerosol removal in the models, errors in simulated atmospheric transport towards the Arctic in most models also contribute to the underestimation of the Arctic aerosol concentrations.

Published
2016
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16. Climate model projections from the Scenario Model Intercomparison Project (ScenarioMIP) of CMIP6

Author

Tebaldi, C, Debeire, K, Eyring, V, Fischer, E, Fyfe, J, Friedlingstein, P, Knutti, R, Lowe, J, O'Neill, B, Sanderson, B, van Vuuren, D, Riahi, K, Meinshausen, M, Nicholls, Z, Tokarska, KB, Hurtt, G, Kriegler, E, Lamarque, J-F, Meehl, G, Moss, R, Bauer, SE, Boucher, O, Brovkin, V, Byun, Y-H, Dix, M, Gualdi, S, Guo, H, John, JG, Kharin, S, Kim, Y, Koshiro, T, Ma, L, Olivie, D, Panickal, S, Qiao, F, Rong, X, Rosenbloom, N, Schupfner, M, Seferian, R, Sellar, A, Semmler, T, Shi, X, Song, Z, Steger, C, Stouffer, R, Swart, N, Tachiiri, K, Tang, Q, Tatebe, H, Voldoire, A, Volodin, E, Wyser, K, Xin, X, Yang, S, Yu, Y, Ziehn, T, Tebaldi, C, Debeire, K, Eyring, V, Fischer, E, Fyfe, J, Friedlingstein, P, Knutti, R, Lowe, J, O'Neill, B, Sanderson, B, van Vuuren, D, Riahi, K, Meinshausen, M, Nicholls, Z, Tokarska, KB, Hurtt, G, Kriegler, E, Lamarque, J-F, Meehl, G, Moss, R, Bauer, SE, Boucher, O, Brovkin, V, Byun, Y-H, Dix, M, Gualdi, S, Guo, H, John, JG, Kharin, S, Kim, Y, Koshiro, T, Ma, L, Olivie, D, Panickal, S, Qiao, F, Rong, X, Rosenbloom, N, Schupfner, M, Seferian, R, Sellar, A, Semmler, T, Shi, X, Song, Z, Steger, C, Stouffer, R, Swart, N, Tachiiri, K, Tang, Q, Tatebe, H, Voldoire, A, Volodin, E, Wyser, K, Xin, X, Yang, S, Yu, Y, and Ziehn, T

Abstract

The Scenario Model Intercomparison Project (ScenarioMIP) defines and coordinates the main set of future climate projections, based on concentration-driven simulations, within the Coupled Model Intercomparison Project phase 6 (CMIP6). This paper presents a range of its outcomes by synthesizing results from the participating global coupled Earth system models. We limit our scope to the analysis of strictly geophysical outcomes: mainly global averages and spatial patterns of change for surface air temperature and precipitation. We also compare CMIP6 projections to CMIP5 results, especially for those scenarios that were designed to provide continuity across the CMIP phases, at the same time highlighting important differences in forcing composition, as well as in results. The range of future temperature and precipitation changes by the end of the century (2081–2100) encompassing the Tier 1 experiments based on the Shared Socioeconomic Pathway (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) and SSP1-1.9 spans a larger range of outcomes compared to CMIP5, due to higher warming (by close to 1.5 ∘C) reached at the upper end of the 5 %–95 % envelope of the highest scenario (SSP5-8.5). This is due to both the wider range of radiative forcing that the new scenarios cover and the higher climate sensitivities in some of the new models compared to their CMIP5 predecessors. Spatial patterns of change for temperature and precipitation averaged over models and scenarios have familiar features, and an analysis of their variations confirms model structural differences to be the dominant source of uncertainty. Models also differ with respect to the size and evolution of internal variability as measured by individual models' initial condition ensemble spreads, according to a set of initial condition ensemble simulations available under SSP3-7.0. These experiments suggest a tendency for internal variability to decrease along the course of the century in this scenario

Published
2021

17. Non-invasive assessment of hepatic iron stores by MRI

Author

Gandon, Y., Olivie, D., Guyader, D., Aube, C., Oberti, F., Sebille, V., and Deugnier, Y.

Subjects
Iron in the body -- Measurement, Liver -- Medical examination, Magnetic resonance imaging -- Usage
Published
2004

18. Using Transport Diagnostics to Understand Chemistry Climate Model Ozone Simulations

Author

Strahan, S. E, Douglass, A. R, Stolarski, R. S, Akiyoshi, H, Bekki, S, Braesicke, P, Butchart, N, Chipperfield, M. P, Cugnet, D, Dhomse, S, Frith, S. M, Gettleman, A, Hardiman, S. C, Kinnison, D. E, Lamarque, J.-F, Mancini, E, Marchand, M, Michou, M, Morgenstern, O, Nakamura, T, Olivie, D, Pawson, S, Pitari, G, Plummer, D. A, and Pyle, J. A

Subjects
Environment Pollution
Abstract

We demonstrate how observations of N2O and mean age in the tropical and midlatitude lower stratosphere (LS) can be used to identify realistic transport in models. The results are applied to 15 Chemistry Climate Models (CCMs) participating in the 2010 WMO assessment. Comparison of the observed and simulated N2O/mean age relationship identifies models with fast or slow circulations and reveals details of model ascent and tropical isolation. The use of this process-oriented N2O/mean age diagnostic identifies models with compensating transport deficiencies that produce fortuitous agreement with mean age. We compare the diagnosed model transport behavior with a model's ability to produce realistic LS O3 profiles in the tropics and midlatitudes. Models with the greatest tropical transport problems show the poorest agreement with observations. Models with the most realistic LS transport agree more closely with LS observations and each other. We incorporate the results of the chemistry evaluations in the SPARC CCMVal Report (2010) to explain the range of CCM predictions for the return-to-1980 dates for global (60 S-60 N) and Antarctic column ozone. Later (earlier) Antarctic return dates are generally correlated to higher (lower) vortex Cl(sub y) levels in the LS, and vortex Cl(sub y) is generally correlated with the model's circulation although model Cl(sub y) chemistry or Cl(sub y) conservation can have a significant effect. In both regions, models that have good LS transport produce a smaller range of predictions for the return-to-1980 ozone values. This study suggests that the current range of predicted return dates is unnecessarily large due to identifiable model transport deficiencies.

Published
2010

20. Climate responses to anthropogenic emissions of short-lived climate pollutants

Author

Baker, Laura, Collins, W J, Olivie, D. J. L., Cherian, R., Myhre, G., and Quaas, J.

Abstract

Policies to control air quality focus on mitigating emissions of aerosols and their precursors, and other short-lived climate pollutants (SLCPs). On a local scale, these policies will have beneficial impacts on health and crop yields, by reducing particulate matter (PM) and surface ozone concentrations; however, the climate impacts of reducing emissions of SLCPs are less straightforward to predict. In this paper we consider a set of idealised, extreme mitigation strategies, in which the total anthropogenic emissions of individual SLCP emissions species are removed. This provides an upper bound on the potential climate impacts of such air quality strategies. \ud \ud We focus on evaluating the climate responses to changes in anthropogenic emissions of aerosol precursor species: black carbon (BC), organic carbon (OC) and sulphur dioxide (SO2). We perform climate integrations with four fully coupled atmosphere-ocean global climate models (AOGCMs), and examine the effects on global and regional climate of removing the total land-based anthropogenic emissions of each of the three aerosol precursor species. \ud \ud We find that the SO2 emissions reductions lead to the strongest response, with all three models showing an increase in surface temperature focussed in the northern hemisphere high latitudes, and a corresponding increase in global mean precipitation and run-off. Changes in precipitation and run-off patterns are driven mostly by a northward shift in the ITCZ, consistent with the hemispherically asymmetric warming pattern driven by the emissions changes. The BC and OC emissions reductions give a much weaker forcing signal, and there is some disagreement between models in the sign of the climate responses to these perturbations. These differences between models are due largely to natural variability in sea-ice extent, circulation patterns and cloud changes. This large natural variability component to the signal when the ocean circulation and sea-ice are free-running means that the BC and OC mitigation measures do not necessarily lead to a discernible climate response.

Published
2015

21. Robustness and uncertainties of ensemble modeling of Short-Lived Climate Forcers (SLFCs) over Europe

Author

Im, U., Nikolaos Daskalakis, Myriokefalitakis, S., Kanakidou, M., Boris Quennehen, Jean-Christophe Raut, Law, Kathy S., Klimont, Z., Kupiainen, K., Heyes, C., Eckhardt, S., Stohl, A., Lund, M. T., Skeie, R. B., Schulz, M., Olivie, D. J. L., Quaas, J., Cherian, R., Cardon, Catherine, Environmental Chemical Processes Laboratory [Heraklion] (ECPL), Department of Chemistry [Heraklion], University of Crete [Heraklion] (UOC)-University of Crete [Heraklion] (UOC), TROPO - 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 de météorologie physique (LaMP), Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS), International Institute for Applied Systems Analysis [Laxenburg] (IIASA), Norwegian Institute for Air Research (NILU), 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), Leipziger Institut für Meteorologie (LIM), Universität Leipzig [Leipzig], Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-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), and Universität Leipzig

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDE.MCG] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [PHYS.PHYS.PHYS-AO-PH] Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Published
2013

22. Current model capabilities for simulating black carbon and sulfate concentrations in the Arctic atmosphere : a multi-model evaluation using a comprehensive measurement data set

Author

Eckhardt, S., Quennehen, B., Olivie, D. J. L., Berntsen, T. K., Cherian, R., Christensen, J. H., Collins, W., Crepinsek, S., Daskalakis, N., Flanner, M., Herber, A., Heyes, C., Hodnebrog, O., Huang, L., Kanakidou, M., Klimont, Z., Langner, Joakim, Law, K. S., Lund, M. T., Mahmood, R., Massling, A., Myriokefalitakis, S., Nielsen, I. E., Nojgaard, J. K., Quaas, J., Quinn, P. K., Raut, J. -C, Rumbold, S. T., Schulz, M., Sharma, S., Skeie, R. B., Skov, H., Uttal, T., von Salzen, K., Stohl, A., Eckhardt, S., Quennehen, B., Olivie, D. J. L., Berntsen, T. K., Cherian, R., Christensen, J. H., Collins, W., Crepinsek, S., Daskalakis, N., Flanner, M., Herber, A., Heyes, C., Hodnebrog, O., Huang, L., Kanakidou, M., Klimont, Z., Langner, Joakim, Law, K. S., Lund, M. T., Mahmood, R., Massling, A., Myriokefalitakis, S., Nielsen, I. E., Nojgaard, J. K., Quaas, J., Quinn, P. K., Raut, J. -C, Rumbold, S. T., Schulz, M., Sharma, S., Skeie, R. B., Skov, H., Uttal, T., von Salzen, K., and Stohl, A.

Abstract

The concentrations of sulfate, black carbon (BC) and other aerosols in the Arctic are characterized by high values in late winter and spring (so-called Arctic Haze) and low values in summer. Models have long been struggling to capture this seasonality and especially the high concentrations associated with Arctic Haze. In this study, we evaluate sulfate and BC concentrations from eleven different models driven with the same emission inventory against a comprehensive pan-Arctic measurement data set over a time period of 2 years (2008-2009). The set of models consisted of one Lagrangian particle dispersion model, four chemistry transport models (CTMs), one atmospheric chemistry-weather forecast model and five chemistry climate models (CCMs), of which two were nudged to meteorological analyses and three were running freely. The measurement data set consisted of surface measurements of equivalent BC (eBC) from five stations (Alert, Barrow, Pallas, Tiksi and Zeppelin), elemental carbon (EC) from Station Nord and Alert and aircraft measurements of refractory BC (rBC) from six different campaigns. We find that the models generally captured the measured eBC or rBC and sulfate concentrations quite well, compared to previous comparisons. However, the aerosol seasonality at the surface is still too weak in most models. Concentrations of eBC and sulfate averaged over three surface sites are underestimated in winter/spring in all but one model (model means for January-March underestimated by 59 and 37% for BC and sulfate, respectively), whereas concentrations in summer are overestimated in the model mean (by 88 and 44% for July-September), but with overestimates as well as underestimates present in individual models. The most pronounced eBC underestimates, not included in the above multi-site average, are found for the station Tiksi in Siberia where the measured annual mean eBC concentration is 3 times higher than the average annual mean for all other stations. This suggests an u

Published
2015
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23. Multimodel assessment of the factors driving stratospheric ozone evolution over the 21st century

Author

Oman, L. D., Plummer, D. A., Waugh, D. W., Austin, J., Scinocca, J. F., Douglass, A. R., Salawitch, R. J., Canty, T., Akiyoshi, H., Bekki, Slimane, Braesicke, P., Butchart, N., Chipperfield, M. P., Cugnet, David, Dhomse, S., Eyring, V., Frith, S., Hardiman, S. C., Kinnison, D. E., Lamarque, J.-F., Mancini, E., Marchand, Marion, Michou, M., Morgenstern, Olaf, Nakamura, T., Nielsen, J. E., Olivie, D., Pitari, G., Pyle, J., Rozanov, E., Shepherd, T. G., Shibata, K., Stolarski, R. S., Teyssedre, H., Tian, W., Yamashita, Y., Ziemke, J. R., Morton K. Blaustein Department of Earth and Planetary Sciences [Baltimore], Johns Hopkins University (JHU), NASA Goddard Space Flight Center (GSFC), Canadian Centre for Climate Modelling and Analysis (CCCma), Environment and Climate Change Canada, NOAA Geophysical Fluid Dynamics Laboratory (GFDL), National Oceanic and Atmospheric Administration (NOAA), University Corporation for Atmospheric Research (UCAR), University of Maryland [College Park], University of Maryland System, National Institute for Environmental Studies (NIES), 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), NCAS-Climate [Cambridge], Department of Chemistry [Cambridge, UK], University of Cambridge [UK] (CAM)-University of Cambridge [UK] (CAM), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office [Exeter], School of Earth and Environment [Leeds] (SEE), University of Leeds, DLR Institut für Physik der Atmosphäre (IPA), Deutsches Zentrum für Luft- und Raumfahrt [Oberpfaffenhofen-Wessling] (DLR), Science Systems and Applications, Inc. [Lanham] (SSAI), National Center for Atmospheric Research [Boulder] (NCAR), University of L'Aquila [Italy] (UNIVAQ), 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), National Institute of Water and Atmospheric Research [Lauder] (NIWA), Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center (PMOD/WRC), Department of Physics [Toronto], University of Toronto, Meteorological Research Institute [Tsukuba] (MRI), Japan Meteorological Agency (JMA), NASA, MAP, ACMAP, Aura programs, NSF Large‐scale Climate Dynamics program., European Commission, European Project: 226365,EC:FP7:ENV,FP7-ENV-2008-1,RECONCILE(2009), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), and Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], ozone, Stratospheric ozone, future evolution, stratosphere, Climate change, chemistry-climate models, CCMVal
Abstract

International audience; The evolution of stratospheric ozone from 1960 to 2100 is examined in simulations from 14 chemistry-climate models, driven by prescribed levels of halogens and greenhouse gases. There is general agreement among the models that total column ozone reached a minimum around year 2000 at all latitudes, projected to be followed by an increase over the first half of the 21st century. In the second half of the 21st century, ozone is projected to continue increasing, level off, or even decrease depending on the latitude. Separation into partial columns above and below 20 hPa reveals that these latitudinal differences are almost completely caused by differences in the model projections of ozone in the lower stratosphere. At all latitudes, upper stratospheric ozone increases throughout the 21st century and is projected to return to 1960 levels well before the end of the century, although there is a spread among models in the dates that ozone returns to specific historical values. We find decreasing halogens and declining upper atmospheric temperatures, driven by increasing greenhouse gases, contribute almost equally to increases in upper stratospheric ozone. In the tropical lower stratosphere, an increase in upwelling causes a steady decrease in ozone through the 21st century, and total column ozone does not return to 1960 levels in most of the models. In contrast, lower stratospheric and total column ozone in middle and high latitudes increases during the 21st century, returning to 1960 levels well before the end of the century in most models.

Published
2010
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24. The Impact of Traffic Emissions on Atmospheric Ozone and OH: Results from QUANTIFY

Author

HOOR P., BORKEN-KLEEFELD J., CARO D., ENDRESEN O., GAUSS M., GREWE F., HAUGLUSTAINE D., ISAKSEN I. S. A., JÖCKEL P, LELIEVELD J., MEIJER E., OLIVIE D., PRATHER M. J., SCHNADT POBERAJ C., STAEHELIN J., TANG Q., VAN AARDENNE John, VAN VELTHOVEN Peter, and SAUSEN R.

Abstract

o estimate the impact of emissions by road, aircraft and ship traffic on ozone and OH of the present-day atmosphere seven different atmospheric chemistry models simulated the atmospheric composition of the year 2003. Based on newly developed global emission inventories for road, maritime and aircraft emission data sets each model performed a series of five simulations: A base scenario using the full set of emissions, three sensitivity studies with each individual sector of transport reduced by 5% and one simulation with all traffic related emissions reduced by 5%. The approach minimizes non-linearities in atmospheric chemical effects and are later scaled to 100%. The global annual mean impact of ship emissions on ozone in the boundary layer leads to an increase of ozone of 1.2%, followed by road (0.87%) and aircraft emissions (0.3%). In the upper troposphere between 200¿300 hPa both road and ship traffic affect ozone by 1.1%, whereas aircraft emissions contribute 0.9%. However, the sensitivity of ozone formation per NOx molecule emitted is highest for aircraft exhausts. The local maximum effect of the summed traffic emissions on the ozone column predicted by the models is 4.0 DU and occurs over the northern subtropical Atlantic. The impact of traffic emissions on total ozone in the Southern Hemisphere is approximately half of the northern hemispheric perturbation. Below 800 hPa both ozone and OH respond most sensitively to ship emissions in the marine boundary layer over the Atlantic, where the effect can exceed 10% (zonal mean) which is 80% of the total traffic induced ozone perturbation. In the Southern Hemisphere ship emissions contribute relatively strongly to the total ozone perturbation by 60%¿80% throughout the year (equivalent to 1¿1.5 ppbv). Road emissions have the strongest impact on ozone in the continental boundary layer and the free troposphere in summer. They also affect the upper troposphere particularly during northern summer associated with strong convection in mid latitudes. Ozone perturbations due to road traffic show the strongest seasonal cycle in the northern troposphere, and can even change sign in the continental boundary layer during winter. The OH concentration in the boundary layer is most strongly affected by ship emissions, which has a significant influence on the lifetime of many trace gases including methane. Methane lifetime changes due to ship emissions amount to 4.1%, followed by road (1.6%) and air traffic (1.0%)., JRC.H.2-Air and Climate

Published
2008

25. The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY

Author

Hoor, P., primary, Borken-Kleefeld, J., additional, Caro, D., additional, Dessens, O., additional, Endresen, O., additional, Gauss, M., additional, Grewe, V., additional, Hauglustaine, D., additional, Isaksen, I. S. A., additional, Jöckel, P., additional, Lelieveld, J., additional, Meijer, E., additional, Olivie, D., additional, Prather, M., additional, Schnadt Poberaj, C., additional, Staehelin, J., additional, Tang, Q., additional, van Aardenne, J., additional, van Velthoven, P., additional, and Sausen, R., additional

Published
2008
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49. Evaluation of natural aerosols in CRESCENDO Earth system models (ESMs): Mineral dust

Author

F. M. O'Connor, P. Le Sager, Tommi Bergman, Kenneth S. Carslaw, T. P. C. van Noije, Béatrice Marticorena, Christopher Dearden, Samuel Albani, Joseph M. Prospero, Cat Scott, Michael Schulz, Ramiro Checa-Garcia, Yves Balkanski, Anne Cozic, Dirk Jan Leo Oliviè, Pierre Nabat, Martine Michou, Checa-Garcia, R, Balkanski, Y, Albani, S, Bergman, T, Carslaw, K, Cozic, A, Dearden, C, Marticorena, B, Michou, M, Van Noije, T, Nabat, P, O'Connor, F, Olivie, D, Prospero, J, Le Sager, P, Schulz, M, Scott, C, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Paris (UP)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), 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), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), 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), Department of Earth and Environmental Sciences [Milano], Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Royal Netherlands Meteorological Institute (KNMI), Institute for Climate and Atmospheric Science [Leeds] (ICAS), School of Earth and Environment [Leeds] (SEE), University of Leeds-University of Leeds, Calcul Scientifique (CALCULS), Centre of Excellence for Modelling the Atmosphere and Climate (CEMAC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Groupe de Météorologie de Grande Échelle et Climat (GMGEC), 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)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), 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), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office [Exeter], Norwegian Meteorological Institute [Oslo] (MET), University of Miami [Coral Gables], ANR-19-CE01-0008,CLIMDO,Alteration des poussières minerales par les composés organiques volatiles d'interet climatique(2019), European Project: 708119,H2020,H2020-MSCA-IF-2015,DUSC3(2016), European Project: 641816,H2020,H2020-SC5-2014-two-stage,CRESCENDO(2015), 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 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), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, QC1-999, Mineral dust, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Radiative transfer, Earth System Model, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, QD1-999, Aerosol, Optical depth, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Climate Model, Physics, Dust, Radiative forcing, AERONET, Chemistry, Deposition (aerosol physics), 13. Climate action, [SDE]Environmental Sciences, Environmental science, Moderate-resolution imaging spectroradiometer, Radiative Forcing
Abstract

This paper presents an analysis of the mineral dust aerosol modelled by five Earth system models (ESMs) within the project entitled Coordinated Research in Earth Systems and Climate: Experiments, kNowledge, Dissemination and Outreach (CRESCENDO). We quantify the global dust cycle described by each model in terms of global emissions, together with dry and wet deposition, reporting large differences in the ratio of dry over wet deposition across the models not directly correlated with the range of particle sizes emitted. The multi-model mean dust emissions with five ESMs is 2836 Tg yr−1 but with a large uncertainty due mainly to the difference in the maximum dust particle size emitted. The multi-model mean of the subset of four ESMs without particle diameters larger than 10 µ m is 1664 (σ=651) Tg yr−1. Total dust emissions in the simulations with identical nudged winds from reanalysis give us better consistency between models; i.e. the multi-model mean global emissions with three ESMs are 1613 (σ=278) Tg yr−1, but 1834 (σ=666) Tg yr−1 without nudged winds and the same models. Significant discrepancies in the globally averaged dust mass extinction efficiency explain why even models with relatively similar global dust load budgets can display strong differences in dust optical depth. The comparison against observations has been done in terms of dust optical depths based on MODIS (Moderate Resolution Imaging Spectroradiometer) satellite products, showing global consistency in terms of preferential dust sources and transport across the Atlantic. The global localisation of source regions is consistent with MODIS, but we found regional and seasonal differences between models and observations when we quantified the cross-correlation of time series over dust-emitting regions. To faithfully compare local emissions between models we introduce a re-gridded normalisation method that can also be compared with satellite products derived from dust event frequencies. Dust total deposition is compared with an instrumental network to assess global and regional differences. We find that models agree with observations within a factor of 10 for data stations distant from dust sources, but the approximations of dust particle size distribution at emission contributed to a misrepresentation of the actual range of deposition values when instruments are close to dust-emitting regions. The observed dust surface concentrations also are reproduced to within a factor of 10. The comparison of total aerosol optical depth with AERONET (AErosol RObotic NETwork) stations where dust is dominant shows large differences between models, although with an increase in the inter-model consistency when the simulations are conducted with nudged winds. The increase in the model ensemble consistency also means better agreement with observations, which we have ascertained for dust total deposition, surface concentrations and optical depths (against both AERONET and MODIS retrievals). We introduce a method to ascertain the contributions per mode consistent with the multi-modal direct radiative effects, which we apply to study the direct radiative effects of a multi-modal representation of the dust particle size distribution that includes the largest particles.

Published
2021
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50. Coupling texture analysis and physiological modeling for liver dynamic MRI interpretation.

Author

Mescam M, Bezy-Wendling J, Kretowski M, Jurczuk K, Eliat PA, and Olivie D

Subjects
Carcinoma, Hepatocellular blood supply, Carcinoma, Hepatocellular diagnostic imaging, Humans, Liver blood supply, Liver diagnostic imaging, Liver Neoplasms blood supply, Liver Neoplasms diagnostic imaging, Portal System diagnostic imaging, Portal System physiopathology, Radiography, Carcinoma, Hepatocellular physiopathology, Liver physiopathology, Liver Neoplasms physiopathology, Magnetic Resonance Imaging, Models, Biological
Abstract

We coupled our physiological model of the liver, to a MRI simulator (SIMRI) in order to find image markers of the tumor growth. Some pathological modifications related to the development of Hepatocellular carcinoma are simulated (flows, permeability, vascular density). Corresponding images simulated at typical acquisition phases (arterial, portal) are compared to real images. The evolution of some textural features with arterial flow is also presented.

Published
2007
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