黑碳气溶胶直接辐射强迫及其对中国夏季降水影响的模拟研究

A Numerical Study of Direct Radiative Forcing Due to Black Carbon and Its Effects on the Summer Precipitation in China

利用NCAR的全球大气模式CAM3分析了黑碳气溶胶在大气顶和地表的直接辐射强迫分布及其季节变化,重点讨论了云对黑碳气溶胶直接辐射强迫的影响,以及黑碳气溶胶对中国夏季降水的影响。结果表明:黑碳气溶胶在大气顶和地表的直接辐射强迫分布范围和强度都具有明显的季节变化。有云条件下,黑碳气溶胶在大气顶产生正的直接辐射强迫,全球年平均强迫值为+0.33W.m-2;在地表产生负的直接辐射强迫,全球年平均强迫值为-0.56W.m-2。晴空条件下,黑碳气溶胶在大气顶和地表的全球年平均辐射强迫值分别为+0.21和-0.71W.m-2。云的存在对黑碳气溶胶的辐射强迫产生了很大的影响,使大气顶的正辐射强迫增加,地表的负辐射强迫减小。黑碳气溶胶导致夏季中国北方30°N～45°N之间区域降水明显增加;而中国长江以南地区除了海南和广西的部分城市外,降水明显减少。模拟结果表明,中国夏季近50年来经常发生的南涝北旱并非由黑碳气溶胶引起。

The global mean distribution and seasonal changes of direct radiative forcing due to black carbon(BC)at the top of atmosphere(TOA)and surface and the effect of cloud on BC direct radiative forcing have been investigated by using the CAM3(Community Atmosphere Model Version 3)developed by NCAR.Then,the influence of BC on summer precipitation in China is discussed.The results show that there exist obviously seasonal changes in the global mean distribution and intensity of direct radiative forcing due to BC at ...