Quantification of DMS aerosol-cloud-climate interactions using the ECHAM5-HAMMOZ model in a current climate scenario
Quantification of DMS aerosol-cloud-climate interactions using the ECHAM5-HAMMOZ model in a current climate scenario
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DOI：
10.5194/acp-10-7425-2010
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发表时间：
2010-08
影响因子：
6.3
通讯作者：
M. Thomas;P. Suntharalingam;L. Pozzoli;S. Rast;A. Devasthale;S. Kloster;J. Feichter;T. Lenton
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文献类型：
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作者：
M. Thomas;P. Suntharalingam;L. Pozzoli;S. Rast;A. Devasthale;S. Kloster;J. Feichter;T. Lenton
摘要。利用气溶胶-化学-气候环流模式ECHAM5-HAMMOZ，结合云微物理方案，对海洋二甲基硫化物（DMS）排放对云微物理特性变化的贡献进行了季节性和全球范围的量化。我们评估了人为影响最小的南部海洋的DMS气溶胶-云-气候联系。通过分析两个模拟，考察了活化粒子数、云滴数浓度（CDNC）、云滴有效半径、云量和辐射强迫的变化：一个是根据规定的气气学得出的海洋DMS排放的基线模拟，另一个是关闭海洋DMS排放的模拟。模拟结果表明，该模式较好地模拟了活性颗粒数量和CDNC的季节性，在南半球夏季达到峰值，与浮游植物华度增加一致，并在南半球冬季逐渐下降，达到最小值。与没有DMS的模拟相比，南部海洋上空的CDNC水平在南部夏季的基线模拟中平均高出128%。我们的结果还显示，在此期间，较小尺寸的云滴数量有所增加。我们估计，与关闭DMS排放时相比，使用海洋DMS模拟的夏夏期间，南部海洋的液滴半径最大减少了15-18%，云量平均增加了约2.5%。全球年平均大气顶部DMS气溶胶全天空辐射强迫为- 2.03 W/m2，而夏季南半球海洋的平均DMS气溶胶辐射强迫达到- 9.32 W/m2。
Abstract. The contribution of ocean dimethyl sulfide (DMS) emissions to changes in cloud microphysical properties is quantified seasonally and globally for present day climate conditions using an aerosol-chemistry-climate general circulation model, ECHAM5-HAMMOZ, coupled to a cloud microphysics scheme. We evaluate DMS aerosol-cloud-climate linkages over the southern oceans where anthropogenic influence is minimal. The changes in the number of activated particles, cloud droplet number concentration (CDNC), cloud droplet effective radius, cloud cover and the radiative forcing are examined by analyzing two simulations: a baseline simulation with ocean DMS emissions derived from a prescribed climatology and one in which the ocean DMS emissions are switched off. Our simulations show that the model realistically simulates the seasonality in the number of activated particles and CDNC, peaking during Southern Hemisphere (SH) summer coincident with increased phytoplankton blooms and gradually declining with a minimum in SH winter. In comparison to a simulation with no DMS, the CDNC level over the southern oceans is 128% larger in the baseline simulation averaged over the austral summer months. Our results also show an increased number of smaller sized cloud droplets during this period. We estimate a maximum decrease of up to 15–18% in the droplet radius and a mean increase in cloud cover by around 2.5% over the southern oceans during SH summer in the simulation with ocean DMS compared to when the DMS emissions are switched off. The global annual mean top of the atmosphere DMS aerosol all sky radiative forcing is −2.03 W/m2, whereas, over the southern oceans during SH summer, the mean DMS aerosol radiative forcing reaches −9.32 W/m2.