中国地区大气气溶胶辐射强迫及区域气候效应的数值模拟

Numerical Simulation of the Aerosol Radiative Forcing and Regional Climate Effect over China

利用太阳直接辐射日总量和日照时数等多年观测资料，反演了中国地区大气气溶胶０７５μｍ光学厚度的年、月平均值，分析了我国大气气溶胶状况的时空分布特征。据此，在中国区域气候模式中考虑气溶胶的辐射影响，模拟中国地区气溶胶直接辐射强迫的大小及气候响应的季节变化特征。计算结果表明：我国大气气溶胶光学厚度多年平均分布状况是以四川盆地为大值中心向四周减少；长江中下游武汉附近和南疆盆地为另两个大值中心；青藏高原为气溶胶低值区；我国绝大部分地区春季气溶胶光学厚度值最大，各地气溶胶光学厚度最小值出现的季节则有所不同。气溶胶辐射强迫介于－５３～－１３Ｗ／ｍ２之间；辐射强迫具有春、夏季大，秋、冬季小，冬季南方偏大，夏季北方偏大的特征。气溶胶辐射强迫的分布与其光学厚度的分布基本一致。由于气溶胶的影响，中国大陆地区地面气温均有所下降，四川盆地到长江中下游地区以及青藏高原北侧到河套地区降温最为明显，分别可达－０４ｏＣ和－０５ｏＣ。气候响应具有明显的季节特征。地面气温的变化除与辐射强迫的大小有关外，还受大气环流的影响。

Using daily direct solar radiation and sunshine duration data, we retrieve the annual and monthly mean value of 0.75 μm aerosol optical depth in China to analyze their geographical and temporal distribution. Then, we improve the China Regional Climate Model by adding aerosol radiative effect. With this model, we estimate the aerosol direct radiative forcing and seasonal variation of climate response to this forcing in China. The results show: Sichuan Basin is a high-value center of aerosol optical depth; Wuhan and Nanjing Basin are another two high-value areas; the Tibetan Plateau is a low-value area. In most part of China, the maximum aerosol optical depth occurs in spring, while the minimum occurs in different seasons for different areas. The values of aerosol direct radiative forcing are between -5 3 W/m 2 and -13 W/m 2 . Aerosol direct radiative forcing is larger in spring and summer, and smaller in autumn and winter. In winter, it is larger in the south than in the north, and the vice versa in the summer. The geographical and temporal distribution pattern of aerosol radiative forcing is generally consistent with that of aerosol optical depth. The surface temperatures are generally reduced in China continent due to the effect of aerosol. Two areas are most remarkable: one is from Sichuan Basin to the middle reaches area of the Yangtzi River, the other is from the north Tibetan Plateau to the Hetao area. The changes in these two areas are -0 4 o C and -0 5 o C, respectively. Climate response varies with seasons. The surface temperature varies not only with the change of radiative forcing, but also with general circulation.