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1. Attribution of the Arctic ozone column deficit in March 2011

Author

Isaksen, I. S. A, Zerefos, C., Wang, W.-C., Balis, D., Eleftheratos, K., Rognerud, B., Stordal, F., Berntsen, T. K, LaCasce, J. H, Søvde, O. A, Olivié, D., Orsolini, Y. J, Zyrichidou, I., Prather, M., and Tuinder, O. N. E

Subjects
aerosol composition, aerosol formation, anthropogenic source, cloud cover, cloud microphysics, dust, long range transport, particle size, precipitation (chemistry), size distribution
Abstract

Arctic column ozone reached record low values (∼310 DU) during March of 2011, exposing Arctic ecosystems to enhanced UV-B. We identify the cause of this anomaly using the Oslo CTM2 atmospheric chemistry model driven by ECMWF meteorology to simulate Arctic ozone from 1998 through 2011. CTM2 successfully reproduces the variability in column ozone, from week to week, and from year to year, correctly identifying 2011 as an extreme anomaly over the period. By comparing parallel model simulations, one with all Arctic ozone chemistry turned off on January 1, we find that chemical ozone loss in 2011 is enhanced relative to previous years, but it accounted for only 23% of the anomaly. Weakened transport of ozone from middle latitudes, concurrent with an anomalously strong polar vortex, was the primary cause of the low ozone When the zonal winds relaxed in mid-March 2011, Arctic column ozone quickly recovered.

Published
2012

2. 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

3. The chemical transport model Oslo CTM3

Author

Søvde, O. A, Prather, M. J, Isaksen, I. S. A, Berntsen, T. K, Stordal, F., Zhu, X., Holmes, C. D, and Hsu, J.

Subjects
accuracy assessment, advection, altitude, lightning, parameterization, photolysis, satellite imagery, simulation, spatial resolution
Abstract

We present here the global chemical transport model Oslo CTM3, an update of the Oslo CTM2. The update comprises a faster transport scheme, an improved wet scavenging scheme for large scale rain, updated photolysis rates and a new lightning parameterization. Oslo CTM3 is better parallelized and allows for stable, large time steps for advection, enabling more complex or high spatial resolution simulations. A new treatment of the horizontal distribution of lightning is presented and found to compare well with measurements. The vertical distribution of lightning is updated and found to be a large contributor to CTM2–CTM3 differences, producing more NOx in the tropical middle troposphere, and less at the surface and at high altitudes. Compared with Oslo CTM2, Oslo CTM3 is faster, more capable and has better conceptual models for scavenging, vertical transport and fractional cloud cover. CTM3 captures stratospheric O3 better than CTM2, but shows minor improvements in terms of matching atmospheric observations in the troposphere. Use of the same meteorology to drive the two models shows that some features related to transport are better resolved by the CTM3, such as polar cap transport, while features like transport close to the vortex edge are resolved better in the Oslo CTM2 due to its required shorter transport time step. The longer transport time steps in CTM3 result in larger errors, e.g., near the jets, and when necessary the errors can be reduced by using a shorter time step. Using a time step of 30 min, the new transport scheme captures both large-scale and small-scale variability in atmospheric circulation and transport, with no loss of computational efficiency. We present a version of the new transport scheme which has been specifically tailored for polar studies, resulting in more accurate polar cap transport than the standard CTM3 transport, confirmed by comparison to satellite observations. Inclusion of tropospheric sulfur chemistry and nitrate aerosols in CTM3 is shown to be important to reproduce tropospheric O3, OH and the CH4 lifetime well.

Published
2012

4. 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

5. Radiative forcing in the 21st century due to ozone changes in the troposphere and the lower stratosphere

Author

Gauss, M., Myhre, G., Pitari, G., Prather, M. J., Isaksen, I. S. A., Berntsen, T. K., Brasseur, G. P., Dentener, F. J., Derwent, R. G., Hauglustaine, D. A., Horowitz, L. W., Jacob, D. J., Johnson, M., Law, K. S., Mickley, L. J., Mueller, J.-F., Plantevin, P.-H., Pyle, J. A., Rogers, H. L., Stevenson, D. S., Sundet, J. K., van Weele, M., and Wilde, O.

Subjects
ozone, radiative forcing, stratosphere, troposphere
Abstract

Radiative forcing due to changes in ozone is expected for the 21st century. An assessment on changes in the tropospheric oxidative state through a model intercomparison (“OxComp”) was conducted for the IPCC Third Assessment Report (IPCC-TAR). OxComp estimated tropospheric changes in ozone and other oxidants during the 21st century based on the “SRES” A2p emission scenario. In this study we analyze the results of 11 chemical transport models (CTMs) that participated in OxComp and use them as input for detailed radiative forcing calculations. We also address future ozone recovery in the lower stratosphere and its impact on radiative forcing by applying two models that calculate both tropospheric and stratospheric changes. The results of OxComp suggest an increase in global-mean tropospheric ozone between 11.4 and 20.5 DU for the 21st century, representing the model uncertainty range for the A2p scenario. As the A2p scenario constitutes the worst case proposed in IPCC-TAR we consider these results as an upper estimate. The radiative transfer model yields a positive radiative forcing ranging from 0.40 to 0.78 W m−2 on a global and annual average. The lower stratosphere contributes an additional 7.5–9.3 DU to the calculated increase in the ozone column, increasing radiative forcing by 0.15–0.17 W m−2. The modeled radiative forcing depends on the height distribution and geographical pattern of predicted ozone changes and shows a distinct seasonal variation. Despite the large variations between the 11 participating models, the calculated range for normalized radiative forcing is within 25%, indicating the ability to scale radiative forcing to global-mean ozone column change.

Published
2003

6. Aviation fuel tracer simulation: Model intercomparison and implications

Author

Danilin, M. Y, Fahey, D. W, Schumann, U., Prather, M. J, Penner, J. E, Ko, M. K. W, Weisenstein, D. K, Jackman, C. H, Pitari, G., Kahler, I., Sausen, R., Weaver, C. J, Douglass, A. R, Connell, P. S, Kinnison, D. E, Dentener, F. J, Fleming, E. L, Berntsen, T. K, Isaksen, I. S. A, Haywood, J. M, and Karcher, B.

Subjects
aircraft, atmospheric aerosols, earth atmosphere, exhaust gases, gas emissions, mathematical models, soot, troposphere
Abstract

An upper limit for aircraft-produced perturbations to aerosols and gaseous exhaust products in the upper troposphere and lower stratosphere (UT/LS) is derived using the 1992 aviation fuel tracer simulation performed by eleven global atmospheric models. Key findings are that subsonic aircraft emissions: 1) have not be responsible for the observed water vapor trends at 40°N; 2) could be a significant source of soot mass near 12 km, but not at 20 km, 3) might cause a noticeable increase in the background sulfate aerosol surface area and number densities (but not mass density) near the northern mid-latitude tropopause, and 4) could provide a global, annual mean top of the atmosphere radiative forcing up to +0.006 W/m² and −0.013 W/m² due to emitted soot and sulfur, respectively.

Published
1998

7. Tropospheric Ozone Changes, Radiative Forcing and Attribution to Emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

Author

Stevenson, D.S, Young, P.J, Naik, V, Lamarque, J.-F, Shindell, D. T, Voulgarakis, A, Skeie, R. B, Dalsoren, S. B, Myhre, G, Berntsen, T. K, Folberth, G. A, Rumbold, S. T, Collins, W. J, MacKenzie, I. A, Doherty, R. M, Zeng, G, vanNoije, T. P. C, Strunk, A, Bergmann, D, Cameron-Smith, P, Plummer, D. A, Strode, S. A, Horowitz, L, Lee, Y. H, Szopa, S, Sudo, K, Nagashima, T, Josse, B, Cionni, I, Righi, M, Eyring, V, Conley, A, Bowman, K. W, Wild, O, and Archibald, A

Subjects
Meteorology And Climatology
Abstract

Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (+/-1 standard deviation) in RFs of +/-17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of +/-10 percent. Applying two different tropopause definitions gives differences in RFs of +/-3 percent. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of +/-30 percent for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44+/-12 percent), nitrogen oxides (31 +/- 9 percent), carbon monoxide (15 +/- 3 percent) and non-methane volatile organic compounds (9 +/- 2 percent); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m(−2) DU(−1), a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m(−2); relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF.

Published
2013
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8. Black Carbon Vertical Profiles Strongly Affect Its Radiative Forcing Uncertainty

Author

Samset, B. H, Myhre, G, Schulz, M, Balkanski, Y, Bauer, S, Berntsen, T. K, Bian, H, Bellouin, N, Diehl, T, Easter, R. C, Ghan, S. J, Iversen, T, Kinne, S, Kirkevag, A, Lamarque, J.-F, Lin, G, Liu, X, Penner, J. E, Seland, O, Skeie, R. B, Stier, P, Takemura, T, Tsigaridis, K, and Zhang, K

Subjects
Meteorology And Climatology
Abstract

The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20% of the present uncertainty in modeled BC direct radiative forcing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Additionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40% of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing characteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere.

Published
2013
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9. Radiative Forcing of the Direct Aerosol Effect from AeroCom Phase II Simulations

Author

Myhre, G, Samset, B. H, Schulz, M, Balkanski, Y, Bauer, S, Berntsen, T. K, Bian, H, Bellouin, N, Chin, M, Diehl, T, Easter, R. C, Feichter, J, Ghan, S. J, Hauglustaine, D, Iversen, T, Kinne, S, Kirkevag, A, Lamarque, J.-F, Lin, G, Liu, X, Lund, M. T, Luo, G, Ma, X, vanNoije, T, Penner, J. E, Rasch, P. J, Ruiz, A, Seland, O, Skeie, R. B, Stier, P, Takemura, T, Tsigaridis, K, Wang, P, Wang, Z, Xu, L, Yu, H, Yu, F, Yoon, J. -H, Zhang, K, Zhang, H, and Zhou, C

Subjects
Meteorology And Climatology
Abstract

We report on the AeroCom Phase II direct aerosol effect (DAE) experiment where 16 detailed global aerosol models have been used to simulate the changes in the aerosol distribution over the industrial era. All 16 models have estimated the radiative forcing (RF) of the anthropogenic DAE, and have taken into account anthropogenic sulphate, black carbon (BC) and organic aerosols (OA) from fossil fuel, biofuel, and biomass burning emissions. In addition several models have simulated the DAE of anthropogenic nitrate and anthropogenic influenced secondary organic aerosols (SOA). The model simulated all-sky RF of the DAE from total anthropogenic aerosols has a range from −0.58 to −0.02 W m(sup−2), with a mean of −0.27 W m(sup−2 for the 16 models. Several models did not include nitrate or SOA and modifying the estimate by accounting for this with information slightly strengthens the mean. Modifying the model estimates for missing aerosol components and for the time period 1750 to 2010 results in a mean RF for the DAE of −0.35 W m(sup−2). Compared to AeroCom Phase I (Schulz et al., 2006) we find very similar spreads in both total DAE and aerosol component RF. However, the RF of the total DAE is stronger negative and RF from BC from fossil fuel and biofuel emissions are stronger positive in the present study than in the previous AeroCom study.We find a tendency for models having a strong (positive) BC RF to also have strong (negative) sulphate or OA RF. This relationship leads to smaller uncertainty in the total RF of the DAE compared to the RF of the sum of the individual aerosol components. The spread in results for the individual aerosol components is substantial, and can be divided into diversities in burden, mass extinction coefficient (MEC), and normalized RF with respect to AOD. We find that these three factors give similar contributions to the spread in results

Published
2013
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11. Aerosols at the poles: an AeroCom Phase II multi-model evaluation

Author

Sand, M., Samset, B. H., Balkanski, Y., Bauer, S., Bellouin, N., Berntsen, T. K., Bian, H., Chin, M., Diehl, T., Easter, R., Ghan, S. J., Iversen, T., Kirkevåg, A., Lamarque, J.-F., Lin, G., Liu, X., Luo, G., Myhre, G., Noije, T. V., Penner, J. E., Schulz, M., Seland, Ø., Skeie, R. B., Stier, P., Takemura, T., Tsigaridis, K., Yu, F., Zhang, K., Zhang, H., Center for International Climate and Environmental Research [Oslo] (CICERO), University of Oslo (UiO), 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), 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), Department of Meteorology [Reading], University of Reading (UOR), Joint Center for Earth Systems Technology [Baltimore] (JCET), NASA Goddard Space Flight Center (GSFC)-University of Maryland [Baltimore County] (UMBC), University of Maryland System-University of Maryland System, NASA Goddard Space Flight Center (GSFC), JRC Institute for Environment and Sustainability (IES), European Commission - Joint Research Centre [Ispra] (JRC), Pacific Northwest National Laboratory (PNNL), Atmospheric Chemistry Observations and Modeling Laboratory (ACOML), National Center for Atmospheric Research [Boulder] (NCAR), Norwegian Meteorological Institute [Oslo] (MET), Department of Physics [Oxford], University of Oxford [Oxford], Kyushu University [Fukuoka], Center for Climate Systems Research [New York] (CCSR), Columbia University [New York], Atmospheric Sciences Research Center (ASRC), University at Albany [SUNY], State University of New York (SUNY)-State University of New York (SUNY), University of Maryland [Baltimore County] (UMBC), University of Maryland System-University of Maryland System-NASA Goddard Space Flight Center (GSFC), 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), University of Oxford, and Kyushu University

Subjects
Earth's energy budget, Atmospheric Science, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, Atmospheric sciences, 7. Clean energy, 01 natural sciences, Latitude, lcsh:Chemistry, chemistry.chemical_compound, Sea ice, Sulfate, Optical depth, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, Radiative forcing, lcsh:QC1-999, Aerosol, lcsh:QD1-999, Arctic, chemistry, 13. Climate action, Climatology, Environmental science, lcsh:Physics
Abstract

International audience; Atmospheric aerosols from anthropogenic and natural sources reach the polar regions through long-range transport and affect the local radiation balance. Such transport is, however, poorly constrained in present-day global climate models, and few multi-model evaluations of polar an-thropogenic aerosol radiative forcing exist. Here we compare the aerosol optical depth (AOD) at 550 nm from simulations with 16 global aerosol models from the AeroCom Phase II model intercomparison project with available observations at both poles. We show that the annual mean multi-model median is representative of the observations in Arctic, but that the intermodel spread is large. We also document the geographical distribution and seasonal cycle of the AOD for the individual aerosol species: black carbon (BC) from fossil fuel and biomass burning, sulfate, organic aerosols (OAs), dust, and sea-salt. For a subset of models that represent nitrate and secondary organic aerosols (SOAs), we document the role of these aerosols at high latitudes. The seasonal dependence of natural and anthropogenic aerosols differs with natural aerosols peaking in winter (sea-salt) and spring (dust), whereas AOD from anthropogenic aerosols peaks in late spring and summer. The models produce a median annual mean AOD of 0.07 in the Arctic (de-fined here as north of 60 • N). The models also predict a noteworthy aerosol transport to the Antarctic (south of 70 • S) with a resulting AOD varying between 0.01 and 0.02. The Published by Copernicus Publications on behalf of the European Geosciences Union. 12198 M. Sand et al.: Aerosols at the poles: an AeroCom Phase II multi-model evaluation models have estimated the shortwave anthropogenic radia-tive forcing contributions to the direct aerosol effect (DAE) associated with BC and OA from fossil fuel and biofuel (FF), sulfate, SOAs, nitrate, and biomass burning from BC and OA emissions combined. The Arctic modelled annual mean DAE is slightly negative (−0.12 W m −2), dominated by a positive BC FF DAE in spring and a negative sulfate DAE in summer. The Antarctic DAE is governed by BC FF. We perform sensitivity experiments with one of the AeroCom models (GISS modelE) to investigate how regional emissions of BC and sulfate and the lifetime of BC influence the Arctic and Antarctic AOD. A doubling of emissions in eastern Asia results in a 33 % increase in Arctic AOD of BC. A doubling of the BC lifetime results in a 39 % increase in Arctic AOD of BC. However, these radical changes still fall within the AeroCom model range.

Published
2017

12. 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., Olivié, D. J. L., Berntsen, T. K., Cherian, R., Christensen, J. H., Collins, W., Crepinsek, S., Daskalakis, N., Flanner, M., Herber, A., Heyes, C., Hodnebrog, Ø., Huang, L., Kanakidou, M., Klimont, Z., Langner, J., Law, K. S., Lund, M. T., Mahmood, R., Massling, A., Myriokefalitakis, S., Nielsen, I. E., Nøjgaard, 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., Norwegian Institute for Air Research (NILU), 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), Norwegian Meteorological Institute [Oslo] (MET), Center for International Climate and Environmental Research [Oslo] (CICERO), University of Oslo (UiO), Leipziger Institut für Meteorologie (LIM), Universität Leipzig [Leipzig], Department of Environmental Science [Roskilde] (ENVS), Aarhus University [Aarhus], University of Reading (UOR), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office [Exeter], Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Environmental Chemical Processes Laboratory [Heraklion] (ECPL), Department of Chemistry [Heraklion], University of Crete [Heraklion] (UOC)-University of Crete [Heraklion] (UOC), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), International Institute for Applied Systems Analysis [Laxenburg] (IIASA), Climate Research Division [Toronto], Environment and Climate Change Canada, Swedish Meteorological and Hydrological Institute (SMHI), School of Earth and Ocean Sciences [Victoria] (SEOS), University of Victoria [Canada] (UVIC), COMSATS Institute of Information Technology [Islamabad] (CIIT), Institute of Chemical Engineering Sciences - Hellas [Crete] (ICE-HT), Foundation for Research and Technology - Hellas (FORTH), NOAA Pacific Marine Environmental Laboratory [Seattle] (PMEL), Canadian Centre for Climate Modelling and Analysis (CCCma), and Universität Leipzig

Subjects
lcsh:Chemistry, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Zeppelinobservatoriet, lcsh:QD1-999, [SDE]Environmental Sciences, Miljövetenskap, lcsh:Physics, lcsh:QC1-999, Environmental Sciences
Abstract

International audience; 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 two 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/rBC and sulfate concentrations quite well, compared to past 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 over- 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 three times higher than the average annual mean for all other stations. This suggests an underestimate of BC sources in Russia in the emission inventory used. Based on the campaign data, biomass burning was identified as another cause of the modelling problems. For sulfate, very large differences were found in the model ensemble, with an apparent anti-correlation between modeled surface concentrations and total atmospheric columns. There is a strong correlation between observed sulfate and eBC concentrations with consistent sulfate/eBC slopes found for all Arctic stations, indicating that the sources contributing to sulfate and BC are similar throughout the Arctic and that the aerosols are internally mixed and undergo similar removal. However, only three models reproduced this finding, whereas sulfate and BC are weakly correlated in the other models. Overall, no class of models (e.g., CTMs, CCMs) performed better than the others and differences are independent of model resolution.

Published
2015

13. In situ observations of black carbon in snow and the corresponding spectral surface albedo reduction

Author

Pedersen, C. A., Gallet, J. -C, Ström, Johan, Gerland, S., Hudson, S. R., Forsström, S., Isaksson, E., Berntsen, T. K., Pedersen, C. A., Gallet, J. -C, Ström, Johan, Gerland, S., Hudson, S. R., Forsström, S., Isaksson, E., and Berntsen, T. K.

Abstract

Black carbon (BC) particles emitted from incomplete combustion of fossil fuel and biomass and deposited on snow and ice darken the surface and reduce the surface albedo. Even small initial surface albedo reductions may have larger adjusted effects due to snow morphology changes and changes in the sublimation and snow melt rate. Most of the literature on the effect of BC on snow surface albedo is based on numerical models, and few in situ field measurements exist to confirm this reduction. Here we present an extensive set of concurrent in situ measurements of spectral surface albedo, BC concentrations in the upper 5 cm of the snowpack, snow physical parameters (grain size and depth), and incident solar flux characteristics from the Arctic. From this data set (with median BC concentrations ranging from 5 to 137 ng BC per gram of snow) we are able to separate the BC signature on the snow albedo from the natural snow variability. Our measurements show a significant correlation between BC in snow and spectral surface albedo. Based on these measurements, parameterizations are provided, relating the snow albedo, as a function of wavelength, to the equivalent BC content in the snowpack. The term equivalent BC used here is the elemental carbon concentration inferred from the thermo-optical method adjusted for the fraction of non-BC constituents absorbing sunlight in the snow. The first parameterization is a simple equation which efficiently describes the snow albedo reduction due to the equivalent BC without including details on the snow or BC microphysics. This can be used in models when a simplified description is needed. A second parameterization, including snow grain size information, shows enhanced correspondence with the measurements. The extracted parameterizations are valid for wavelength bands 400-900 nm, constrained for BC concentrations between 1 and 400 ng g(-1), and for an optically thick snowpack. The parameterizations are purely empirical, and particular focus, AuthorCount:8

Published
2015
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19. Evaluating the climate and air quality impacts of short-lived pollutants

Author

Stohl, A., primary, Aamaas, B., additional, Amann, M., additional, Baker, L. H., additional, Bellouin, N., additional, Berntsen, T. K., additional, Boucher, O., additional, Cherian, R., additional, Collins, W., additional, Daskalakis, N., additional, Dusinska, M., additional, Eckhardt, S., additional, Fuglestvedt, J. S., additional, Harju, M., additional, Heyes, C., additional, Hodnebrog, Ø., additional, Hao, J., additional, Im, U., additional, Kanakidou, M., additional, Klimont, Z., additional, Kupiainen, K., additional, Law, K. S., additional, Lund, M. T., additional, Maas, R., additional, MacIntosh, C. R., additional, Myhre, G., additional, Myriokefalitakis, S., additional, Olivié, D., additional, Quaas, J., additional, Quennehen, B., additional, Raut, J.-C., additional, Rumbold, S. T., additional, Samset, B. H., additional, Schulz, M., additional, Seland, Ø., additional, Shine, K. P., additional, Skeie, R. B., additional, Wang, S., additional, Yttri, K. E., additional, and Zhu, T., additional

Published
2015
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20. 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., primary, Quennehen, B., additional, Olivié, D. J. L., additional, Berntsen, T. K., additional, Cherian, R., additional, Christensen, J. H., additional, Collins, W., additional, Crepinsek, S., additional, Daskalakis, N., additional, Flanner, M., additional, Herber, A., additional, Heyes, C., additional, Hodnebrog, Ø., additional, Huang, L., additional, Kanakidou, M., additional, Klimont, Z., additional, Langner, J., additional, Law, K. S., additional, Massling, A., additional, Myriokefalitakis, S., additional, Nielsen, I. E., additional, Nøjgaard, J. K., additional, Quaas, J., additional, Quinn, P. K., additional, Raut, J.-C., additional, Rumbold, S. T., additional, Schulz, M., additional, Skeie, R. B., additional, Skov, H., additional, Lund, M. T., additional, Uttal, T., additional, von Salzen, K., additional, Mahmood, R., additional, and Stohl, A., additional

Published
2015
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23. Modelled black carbon radiative forcing and atmospheric lifetime in AeroCom Phase II constrained by aircraft observations

Author

Samset, B. H., primary, Myhre, G., additional, Herber, A., additional, Kondo, Y., additional, Li, S.-M., additional, Moteki, N., additional, Koike, M., additional, Oshima, N., additional, Schwarz, J. P., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Berntsen, T. K., additional, Bian, H., additional, Chin, M., additional, Diehl, T., additional, Easter, R. C., additional, Ghan, S. J., additional, Iversen, T., additional, Kirkevåg, A., additional, Lamarque, J.-F., additional, Lin, G., additional, Liu, X., additional, Penner, J. E., additional, Schulz, M., additional, Seland, Ø., additional, Skeie, R. B., additional, Stier, P., additional, Takemura, T., additional, Tsigaridis, K., additional, and Zhang, K., additional

Published
2014
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24. The AeroCom evaluation and intercomparison of organic aerosol in global models

Author

Tsigaridis, K., primary, Daskalakis, N., additional, Kanakidou, M., additional, Adams, P. J., additional, Artaxo, P., additional, Bahadur, R., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Benedetti, A., additional, Bergman, T., additional, Berntsen, T. K., additional, Beukes, J. P., additional, Bian, H., additional, Carslaw, K. S., additional, Chin, M., additional, Curci, G., additional, Diehl, T., additional, Easter, R. C., additional, Ghan, S. J., additional, Gong, S. L., additional, Hodzic, A., additional, Hoyle, C. R., additional, Iversen, T., additional, Jathar, S., additional, Jimenez, J. L., additional, Kaiser, J. W., additional, Kirkevåg, A., additional, Koch, D., additional, Kokkola, H., additional, Lee, Y. H, additional, Lin, G., additional, Liu, X., additional, Luo, G., additional, Ma, X., additional, Mann, G. W., additional, Mihalopoulos, N., additional, Morcrette, J.-J., additional, Müller, J.-F., additional, Myhre, G., additional, Myriokefalitakis, S., additional, Ng, N. L., additional, O'Donnell, D., additional, Penner, J. E., additional, Pozzoli, L., additional, Pringle, K. J., additional, Russell, L. M., additional, Schulz, M., additional, Sciare, J., additional, Seland, Ø., additional, Shindell, D. T., additional, Sillman, S., additional, Skeie, R. B., additional, Spracklen, D., additional, Stavrakou, T., additional, Steenrod, S. D., additional, Takemura, T., additional, Tiitta, P., additional, Tilmes, S., additional, Tost, H., additional, van Noije, T., additional, van Zyl, P. G., additional, von Salzen, K., additional, Yu, F., additional, Wang, Z., additional, Zaveri, R. A., additional, Zhang, H., additional, Zhang, K., additional, Zhang, Q., additional, and Zhang, X., additional

Published
2014
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25. Supplementary material to "The AeroCom evaluation and intercomparison of organic aerosol in global models"

Author

Tsigaridis, K., primary, Daskalakis, N., additional, Kanakidou, M., additional, Adams, P. J., additional, Artaxo, P., additional, Bahadur, R., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Benedetti, A., additional, Bergman, T., additional, Berntsen, T. K., additional, Beukes, J. P., additional, Bian, H., additional, Carslaw, K. S., additional, Chin, M., additional, Curci, G., additional, Diehl, T., additional, Easter, R. C., additional, Ghan, S. J., additional, Gong, S. L., additional, Hodzic, A., additional, Hoyle, C. R., additional, Iversen, T., additional, Jathar, S., additional, Jimenez, J. L., additional, Kaiser, J. W., additional, Kirkevåg, A., additional, Koch, D., additional, Kokkola, H., additional, Lee, Y. H., additional, Lin, G., additional, Liu, X., additional, Luo, G., additional, Ma, X., additional, Mann, G. W., additional, Mihalopoulos, N., additional, Morcrette, J.-J., additional, Müller, J.-F., additional, Myhre, G., additional, Myriokefalitakis, S., additional, Ng, S., additional, O'Donnell, D., additional, Penner, J. E., additional, Pozzoli, L., additional, Pringle, K. J., additional, Russell, L. M., additional, Schulz, M., additional, Sciare, J., additional, Seland, Ø., additional, Shindell, D. T., additional, Sillman, S., additional, Skeie, R. B., additional, Spracklen, D., additional, Stavrakou, T., additional, Steenrod, S. D., additional, Takemura, T., additional, Tiitta, P., additional, Tilmes, S., additional, Tost, H., additional, van Noije, T., additional, van Zyl, P. G., additional, von Salzen, K., additional, Yu, F., additional, Wang, Z., additional, Zaveri, R. A., additional, Zhang, H., additional, Zhang, K., additional, Zhang, Q., additional, and Zhang, X., additional

Published
2014
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26. An AeroCom assessment of black carbon in Arctic snow and sea ice

Author

Jiao, C., primary, Flanner, M. G., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Berntsen, T. K., additional, Bian, H., additional, Carslaw, K. S., additional, Chin, M., additional, De Luca, N., additional, Diehl, T., additional, Ghan, S. J., additional, Iversen, T., additional, Kirkevåg, A., additional, Koch, D., additional, Liu, X., additional, Mann, G. W., additional, Penner, J. E., additional, Pitari, G., additional, Schulz, M., additional, Seland, Ø., additional, Skeie, R. B., additional, Steenrod, S. D., additional, Stier, P., additional, Takemura, T., additional, Tsigaridis, K., additional, van Noije, T., additional, Yun, Y., additional, and Zhang, K., additional

Published
2014
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27. Aircraft routing with minimal climate impact: the REACT4C climate cost function modelling approach (V1.0)

Author

Grewe, V., primary, Frömming, C., additional, Matthes, S., additional, Brinkop, S., additional, Ponater, M., additional, Dietmüller, S., additional, Jöckel, P., additional, Garny, H., additional, Tsati, E., additional, Dahlmann, K., additional, Søvde, O. A., additional, Fuglestvedt, J., additional, Berntsen, T. K., additional, Shine, K. P., additional, Irvine, E. A., additional, Champougny, T., additional, and Hullah, P., additional

Published
2014
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29. Elemental carbon measurements in European Arctic snow packs

Author

Forsström, S., Isaksson, E., Skeie, R. B., Ström, Johan, Pedersen, C. A., Hudson, S. R., Berntsen, T. K., Lihavainen, H., Godtliebsen, F., Gerland, S., Forsström, S., Isaksson, E., Skeie, R. B., Ström, Johan, Pedersen, C. A., Hudson, S. R., Berntsen, T. K., Lihavainen, H., Godtliebsen, F., and Gerland, S.

Abstract

AuthorCount:10; Research Council of Norway 165064, 178912, 184724, 178764; SLAC; NPI

Published
2013
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30. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP)

Author

Stevenson, D. S., Young, Paul, Naik, Vaishali, Lamarque, Jean-Francois, Shindell, Drew T., Voulgarakis, A., Skeie, R, Dalsoren, Stig B, Myhre, G, Berntsen, T K, Folberth, G., Rumbold, S, Collins, William J., MacKenzie, Ian A., Doherty, R. M., Zeng, Guang, van Noije, T. P. C., Strunk, A, Bergmann, D., Cameron-Smith, Philip, Plummer, David A, Strode, Sarah, Horowitz, L. W., Lee, Yunha H, Szopa, Sophie, Sudo, K., Nagashima, T, Josse, B, Cionni, I, Righi, M, Eyring, V., Conley, Andrew J, Bowman, Kevin, Wild, Oliver, Archibald, A. T., Stevenson, D. S., Young, Paul, Naik, Vaishali, Lamarque, Jean-Francois, Shindell, Drew T., Voulgarakis, A., Skeie, R, Dalsoren, Stig B, Myhre, G, Berntsen, T K, Folberth, G., Rumbold, S, Collins, William J., MacKenzie, Ian A., Doherty, R. M., Zeng, Guang, van Noije, T. P. C., Strunk, A, Bergmann, D., Cameron-Smith, Philip, Plummer, David A, Strode, Sarah, Horowitz, L. W., Lee, Yunha H, Szopa, Sophie, Sudo, K., Nagashima, T, Josse, B, Cionni, I, Righi, M, Eyring, V., Conley, Andrew J, Bowman, Kevin, Wild, Oliver, and Archibald, A. T.

Published
2013

31. Elemental carbon measurements in European Arctic snow packs

Author

Forsström, S., primary, Isaksson, E., additional, Skeie, R. B., additional, Ström, J., additional, Pedersen, C. A., additional, Hudson, S. R., additional, Berntsen, T. K., additional, Lihavainen, H., additional, Godtliebsen, F., additional, and Gerland, S., additional

Published
2013
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32. Contribution to Chapter 3: Aviation-Produced Aerosols and Cloudiness

Author

Fahey, D. W., Schumann, U, Ackerman, S, Artaxo, P, Boucher, O, Danilin, M. Y., Karcher, B, Minnis, P, Nakajima, Toon, O. B., Ayers, J. K., Berntsen, T. K., Connell, P. S., Dentener, F. J., Doelling, D. R., Dopelheuer, A, Fleming, E. L., Gierens, K, Jackman, C. H., Jager, H, Jensen, E. J., Kent, G. S., Kohler, I, Meerkotter, R, Pitari, Giovanni, Prather, M. J., and Strom, J.

Published
1999

33. An AeroCom assessment of black carbon in Arctic snow and sea ice

Author

Jiao, C., primary, Flanner, M. G., additional, Balkanski, Y., additional, Bauer, S. E., additional, Bellouin, N., additional, Berntsen, T. K., additional, Bian, H., additional, Carslaw, K. S., additional, Chin, M., additional, De Luca, N., additional, Diehl, T., additional, Ghan, S. J., additional, Iversen, T., additional, Kirkevåg, A., additional, Koch, D., additional, Liu, X., additional, Mann, G. W., additional, Penner, J. E., additional, Pitari, G., additional, Schulz, M., additional, Seland, \\O., additional, Skeie, R. B., additional, Steenrod, S. D., additional, Stier, P., additional, Takemura, T., additional, Tsigaridis, K., additional, van Noije, T., additional, Yun, Y., additional, and Zhang, K., additional

Published
2013
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34. Aircraft routing with minimal climate impact: the REACT4C climate cost function modelling approach (V1.0)

Author

Grewe, V., primary, Frömming, C., additional, Matthes, S., additional, Brinkop, S., additional, Ponater, M., additional, Dietmüller, S., additional, Jöckel, P., additional, Garny, H., additional, Tsati, E., additional, Søvde, O. A., additional, Fuglestvedt, J., additional, Berntsen, T. K., additional, Shine, K. P., additional, Irvine, E. A., additional, Champougny, T., additional, and Hullah, P., additional

Published
2013
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35. Supplementary material to "Aircraft routing with minimal climate impact: the REACT4C climate cost function modelling approach (V1.0)"

Author

Grewe, V., primary, Frömming, C., additional, Matthes, S., additional, Brinkop, S., additional, Ponater, M., additional, Dietmüller, S., additional, Jöckel, P., additional, Garny, H., additional, Tsati, E., additional, Søvde, O. A., additional, Fuglestvedt, J., additional, Berntsen, T. K., additional, Shine, K. P., additional, Irvine, E. A., additional, Champougny, T., additional, and Hullah, P., additional

Published
2013
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37. Black carbon vertical profiles strongly affect its radiative forcing uncertainty

Author

Samset, B. H., primary, Myhre, G., additional, Schulz, M., additional, Balkanski, Y., additional, Bauer, S., additional, Berntsen, T. K., additional, Bian, H., additional, Bellouin, N., additional, Diehl, T., additional, Easter, R. C., additional, Ghan, S. J., additional, Iversen, T., additional, Kinne, S., additional, Kirkevåg, A., additional, Lamarque, J.-F., additional, Lin, G., additional, Liu, X., additional, Penner, J., additional, Seland, Ø., additional, Skeie, R.B., additional, Stier, P., additional, Takemura, T., additional, Tsigaridis, K., additional, and Zhang, K., additional

Published
2012
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38. Supplementary material to "Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP)"

Author

Stevenson, D. S., primary, Young, P. J., additional, Naik, V., additional, Lamarque, J.-F., additional, Shindell, D. T., additional, Voulgarakis, A., additional, Skeie, R. B., additional, Dalsoren, S. B., additional, Myhre, G., additional, Berntsen, T. K., additional, Folberth, G. A., additional, Rumbold, S. T., additional, Collins, W. J., additional, MacKenzie, I. A., additional, Doherty, R. M., additional, Zeng, G., additional, van Noije, T. P. C., additional, Strunk, A., additional, Bergmann, D., additional, Cameron-Smith, P., additional, Plummer, D. A., additional, Strode, S. A., additional, Horowitz, L., additional, Lee, Y. H., additional, Szopa, S., additional, Sudo, K., additional, Nagashima, T., additional, Josse, B., additional, Cionni, I., additional, Righi, M., additional, Eyring, V., additional, Conley, A., additional, Bowman, K. W., additional, and Wild, O., additional

Published
2012
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39. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP)

Author

Stevenson, D. S., primary, Young, P. J., additional, Naik, V., additional, Lamarque, J.-F., additional, Shindell, D. T., additional, Voulgarakis, A., additional, Skeie, R. B., additional, Dalsoren, S. B., additional, Myhre, G., additional, Berntsen, T. K., additional, Folberth, G. A., additional, Rumbold, S. T., additional, Collins, W. J., additional, MacKenzie, I. A., additional, Doherty, R. M., additional, Zeng, G., additional, van Noije, T. P. C., additional, Strunk, A., additional, Bergmann, D., additional, Cameron-Smith, P., additional, Plummer, D. A., additional, Strode, S. A., additional, Horowitz, L., additional, Lee, Y. H., additional, Szopa, S., additional, Sudo, K., additional, Nagashima, T., additional, Josse, B., additional, Cionni, I., additional, Righi, M., additional, Eyring, V., additional, Conley, A., additional, Bowman, K. W., additional, and Wild, O., additional

Published
2012
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40. P-009

Author

Silva, Raquel A., primary, Anenberg, Susan C., additional, West, J. Jason, additional, Lamarque, Jean-Francois, additional, Shindell, Drew, additional, Bergmann, Daniel, additional, Berntsen, T. K., additional, Cameron-Smith, Philip, additional, Collins, William J., additional, Ghan, Steven J., additional, Josse, Beatrice, additional, Nagashima, Tatsuya, additional, Naik, Vaishali, additional, Plummer, David, additional, Rodriguez, Jose M., additional, Szopa, Sophie, additional, and Zeng, Guang, additional

Published
2012
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41. Supplementary material to "Radiative forcing of the direct aerosol effect from AeroCom Phase II simulations"

Author

Myhre, G., primary, Samset, B. H., additional, Schulz, M., additional, Balkanski, Y., additional, Bauer, S., additional, Berntsen, T. K., additional, Bian, H., additional, Bellouin, N., additional, Chin, M., additional, Diehl, T., additional, Easter, R. C., additional, Feichter, J., additional, Ghan, S. J., additional, Hauglustaine, D., additional, Iversen, T., additional, Kinne, S., additional, Kirkevåg, A., additional, Lamarque, J.-F., additional, Lin, G., additional, Liu, X., additional, Luo, G., additional, Ma, X., additional, Penner, J. E., additional, Rasch, P. J., additional, Seland, Ø., additional, Skeie, R. B., additional, Stier, P., additional, Takemura, T., additional, Tsigaridis, K., additional, Wang, Z., additional, Xu, L., additional, Yu, H., additional, Yu, F., additional, Yoon, J.-H., additional, Zhang, K., additional, Zhang, H., additional, and Zhou, C., additional

Published
2012
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42. Radiative forcing of the direct aerosol effect from AeroCom Phase II simulations

Author

Myhre, G., primary, Samset, B. H., additional, Schulz, M., additional, Balkanski, Y., additional, Bauer, S., additional, Berntsen, T. K., additional, Bian, H., additional, Bellouin, N., additional, Chin, M., additional, Diehl, T., additional, Easter, R. C., additional, Feichter, J., additional, Ghan, S. J., additional, Hauglustaine, D., additional, Iversen, T., additional, Kinne, S., additional, Kirkevåg, A., additional, Lamarque, J.-F., additional, Lin, G., additional, Liu, X., additional, Luo, G., additional, Ma, X., additional, Penner, J. E., additional, Rasch, P. J., additional, Seland, Ø., additional, Skeie, R. B., additional, Stier, P., additional, Takemura, T., additional, Tsigaridis, K., additional, Wang, Z., additional, Xu, L., additional, Yu, H., additional, Yu, F., additional, Yoon, J.-H., additional, Zhang, K., additional, Zhang, H., additional, and Zhou, C., additional

Published
2012
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43. Future impact of traffic emissions on atmospheric ozone and OH based on two scenarios

Author

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

Published
2012
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45. The chemical transport model Oslo CTM3

Author

Søvde, O. A., primary, Prather, M. J., additional, Isaksen, I. S. A., additional, Berntsen, T. K., additional, Stordal, F., additional, Zhu, X., additional, Holmes, C. D., additional, and Hsu, J., additional

Published
2012
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49. Future impact of non-land based traffic emissions on atmospheric ozone and OH – an optimistic scenario and a possible mitigation strategy

Author

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

Published
2011
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50. Radiative forcing in the 21st century due to ozone changes in the troposphere and the lower stratosphere

Author

Gauss, M, Myhre, G, Pitari, G, Prather, M J, Isaksen, I S A, Berntsen, T K, Brasseur, G P, Dentener, F J, Derwent, R G, Hauglustaine, D A, Horowitz, L W, Jacob, D J, Johnson, M, Law, K S, Mickley, L J, Muller, J F, Plantevin, P H, Pyle, J A, Rogers, H L, Stevenson, D S, Sundet, J K, van Weele, M, Wild, O, Gauss, M, Myhre, G, Pitari, G, Prather, M J, Isaksen, I S A, Berntsen, T K, Brasseur, G P, Dentener, F J, Derwent, R G, Hauglustaine, D A, Horowitz, L W, Jacob, D J, Johnson, M, Law, K S, Mickley, L J, Muller, J F, Plantevin, P H, Pyle, J A, Rogers, H L, Stevenson, D S, Sundet, J K, van Weele, M, and Wild, O

Abstract

Radiative forcing due to changes in ozone is expected for the 21st century. An assessment on changes in the tropospheric oxidative state through a model intercomparison ("OxComp'') was conducted for the IPCC Third Assessment Report (IPCC-TAR). OxComp estimated tropospheric changes in ozone and other oxidants during the 21st century based on the "SRES'' A2p emission scenario. In this study we analyze the results of 11 chemical transport models (CTMs) that participated in OxComp and use them as input for detailed radiative forcing calculations. We also address future ozone recovery in the lower stratosphere and its impact on radiative forcing by applying two models that calculate both tropospheric and stratospheric changes. The results of OxComp suggest an increase in global-mean tropospheric ozone between 11.4 and 20.5 DU for the 21st century, representing the model uncertainty range for the A2p scenario. As the A2p scenario constitutes the worst case proposed in IPCC-TAR we consider these results as an upper estimate. The radiative transfer model yields a positive radiative forcing ranging from 0.40 to 0.78 W m(-2) on a global and annual average. The lower stratosphere contributes an additional 7.5-9.3 DU to the calculated increase in the ozone column, increasing radiative forcing by 0.15-0.17 W m(-2). The modeled radiative forcing depends on the height distribution and geographical pattern of predicted ozone changes and shows a distinct seasonal variation. Despite the large variations between the 11 participating models, the calculated range for normalized radiative forcing is within 25%, indicating the ability to scale radiative forcing to global-mean ozone column change.

Published
2003

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