Circulation responses to regional aerosol climate forcing in summer over East Asia
Circulation responses to regional aerosol climate forcing in summer over East Asia
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DOI：
10.1007/s00382-018-4267-3
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发表时间：
2018-12-01
期刊：
影响因子：
4.6
通讯作者：
Chen, Jen-Ping
中科院分区：
文献类型：
--
作者：
Chen, Guoxing;Wang, Wei-Chyung;Chen, Jen-Ping
在东亚，环流对人为气溶胶辐射强迫的响应主导着气溶胶-降水相互作用。为了获得更多的信息，本研究分析了CESM模拟的环流变化与两种情况之间气溶胶增加引起的北旱南涝模式有关。一种情况是由1850年全球排放清单驱动的，而另一种情况则使用了除东亚以外所有地区的相同排放量，东亚地区人为排放了2000年的气溶胶和前体。结果表明，气溶胶增加引起的降温在中纬度地区达到峰值，引起对流层两次介入异常环流。近地面，地面气压的增加削弱了南风带，减少了整个华东地区的水汽输送。同时，在自由对流层，异常环流表现出显著的经向变化。在北纬25度-45度以上发生辐合，部分补偿了低层水汽输送的减少，而向北的辐散则加剧了水汽缺乏。此外，急流的南移刺激了北纬32度以南和北部的异常上升和下沉运动，这些变化的组合导致长江流域降水增加，华北降水减少。
For East Asia, circulation responses to anthropogenic aerosol radiative forcing dominate aerosol-precipitation interactions. To gain insights, this study analyzed CESM simulated circulation changes related to the north drought and south flood' pattern caused by aerosol increases between two cases. One case was driven by the year-1850 global emission inventory, whereas the other used identical emissions for all regions except East Asia where anthropogenic emissions of aerosols and precursors of the year-2000 were imposed. Results show that the cooling caused by increased aerosols, which peaks at the middle latitudes, induces two intervened anomalous circulations in the troposphere. Near the surface, the increased land pressure weakens the southerlies and reduces the moisture transport for the entire eastern China. Meanwhile, in the free troposphere, the anomalous circulation exhibits remarkable meridional variations. While convergence occurs over 25 degrees-45 degrees N which partially compensates the decrease of moisture transport from lower levels, divergence develops over regions to the north which enhances the moisture deficiency. In addition, the southward shift of the jet stream stimulates anomalous rising and sinking motions over the south and north of 32 degrees N. The combination of these changes leads to precipitation increase in the Yangtze River Valley but decrease over North China.