近10年东亚沙尘气溶胶辐射强迫与温度响应

Radiative Force and Temperature Response of Dust Aerosol over East Asia in Recent Decade

利用一个耦合了在线沙尘模型的区域气候模式RegCM3,对2000-2009年东亚沙尘气溶胶辐射强迫及温度响应进行了数值模拟。结果表明:(1)东亚沙尘气溶胶分布具有明显的地理差异和季节差异,柱含量高值区主要位于塔克拉玛干沙漠和巴丹吉林沙漠,最大值均在1 000mg.m-2以上;从季节分布来看,春季最大,冬季次之,秋季最小。(2)沙尘气溶胶辐射强迫与分布具有较好的对应关系。东亚地区大气顶辐射强迫,春、秋季分别为-1.72W.m-2和-1.17W.m-2;而地表辐射强迫,春、秋季分别为-4.34W.m-2和-2.33W.m-2。(3)沙尘气溶胶使地表温度降低,东亚地区平均地表温度降低,春季为0.154℃,秋季为0.085℃。(4)沙尘气溶胶在不同高度对气温有不同的影响。在对流层下层,沙尘气溶胶使得气温降低,随高度增加,气温降幅逐渐减小;春季在300～400hPa出现升温区,而秋季升温区出现的高度东西差别较大。

A regional climate model RegCM3 coupled with an on-line dust module is used to simulate the radiative force and temperature response of dust aerosol over East Asia in the recent decade from 2000 to 2009.The simulated results show that the geographical and seasonal differences of dust aerosol distribution over East Asia are obvious.There exist two extremes of dust aerosol with column burden larger than 1 000 mg·m-2,one is in the Takelamagan desert of Xinjiang Uigur Autonomous Region,China,and the other is in the Badain Jaran desert of Inner Mongolian Autonomous Region,China.The maximum value of column burden appears in spring,the secondary maximum in winter and the minimum in autumn.The radiative force of dust aerosol has similar distribution characteristic with column burden.The averaged radiative force over East Asia at the top of atmosphere is-1.72 W·m-2 in spring and-1.17 W·m-2 in autumn,and that at the surface is-4.34 W·m-2 in spring and-2.33 W·m-2 in autumn.The surface temperature is decreased by dust aerosol,and the averaged decreased extent over East Asia is 0.154 ℃ in spring and 0.085 ℃ in autumn.There are different impacts of dust aerosol on air temperature at different heights.The air temperature is decreased by dust aerosol in lower troposphere,and the decreased extent is diminished with the height increasing.The air temperature turns to increase by dust aerosol at the heights of 300~400 hPa in spring,but it is more complicated in autumn.