The Representation of Sea Salt Aerosols and Their Role in Polar Climate Within CMIP6
The Representation of Sea Salt Aerosols and Their Role in Polar Climate Within CMIP6
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DOI：
10.1029/2022jd038235
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发表时间：
2023-03
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通讯作者：
R. Lapere;Jennie L. Thomas;L. Marelle;A. Ekman;M. Frey;M. Lund;R. Makkonen;A. Ranjithkumar;M. Salter;B. Samset;M. Schulz;L. Sogacheva;Xin Yang;P. Zieger
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作者：
R. Lapere;Jennie L. Thomas;L. Marelle;A. Ekman;M. Frey;M. Lund;R. Makkonen;A. Ranjithkumar;M. Salter;B. Samset;M. Schulz;L. Sogacheva;Xin Yang;P. Zieger
在气候模式中，特别是在两极，天然气溶胶及其与云的相互作用仍然是一个重要的不确定性。本文利用CMIP6的12个气候模式研究了北极和南极海盐气溶胶（SSaer）的行为。我们研究了控制SSaer丰度的驱动因素，并根据源函数的选择和大气中气溶胶过程的表示显示出很大的差异。在接近两极的地方，CMIP6模式与观测到的地表浓度的季节周期不匹配，这可能是由于缺少冬季SSaer源，如吹雪。在远离两极的地方，模拟的浓度具有正确的季节性，但具有高达一个数量级的正平均偏差。SSaer光学深度由MODIS数据导出，并与模拟值进行了比较，除了冬季月份外，结果一致。与表面浓度相比，气溶胶光学深度的一致性更好，这可能表明需要改进模拟极地SSaer的垂直分布、大小分布和/或吸湿性。CMIP6中使用的源函数发射的小SSaer数量非常不同，可能会加剧这些偏远地区云-气溶胶相互作用的不确定性。对于未来的气候情景SSP126和SSP585，我们表明，在21世纪末，SSaer浓度在两极增加，北极的浓度是20世纪中期的两倍多。工业化前气候CMIP6实验表明，由于SSaer，极地辐射收支存在很大的不确定性。
Natural aerosols and their interactions with clouds remain an important uncertainty within climate models, especially at the poles. Here, we study the behavior of sea salt aerosols (SSaer) in the Arctic and Antarctic within 12 climate models from CMIP6. We investigate the driving factors that control SSaer abundances and show large differences based on the choice of the source function, and the representation of aerosol processes in the atmosphere. Close to the poles, the CMIP6 models do not match observed seasonal cycles of surface concentrations, likely due to the absence of wintertime SSaer sources such as blowing snow. Further away from the poles, simulated concentrations have the correct seasonality, but have a positive mean bias of up to one order of magnitude. SSaer optical depth is derived from the MODIS data and compared to modeled values, revealing good agreement, except for winter months. Better agreement for aerosol optical depth than surface concentration may indicate a need for improving the vertical distribution, the size distribution and/or hygroscopicity of modeled polar SSaer. Source functions used in CMIP6 emit very different numbers of small SSaer, potentially exacerbating cloud‐aerosol interaction uncertainties in these remote regions. For future climate scenarios SSP126 and SSP585, we show that SSaer concentrations increase at both poles at the end of the 21st century, with more than two times mid‐20th century values in the Arctic. The pre‐industrial climate CMIP6 experiments suggest there is a large uncertainty in the polar radiative budget due to SSaer.