基于MERRA2再分析资料的全球AOD和沙尘AOD空间分布及趋势

Spatial distribution and trend of global and dust AOD based on MERRA2 reanalysis data

利用MERRA2再分析资料和气溶胶遥感观测网(AERONET)观测资料,分析了全球气溶胶和沙尘气溶胶光学厚度(AOD)的空间分布及趋势.结果表明, MERRA2的AOD与AERONET观测结果相关性较好,相关系数为0.44~0.92,均方根误差为0.03~0.52,均方根误差较大的站点多位于东亚地区. AOD<0.2的站点多位于北美、澳大利亚和欧洲, MERRA2对AOD值较低的站点高估0~0.04.AOD值较高的站点多位于东亚、南美、非洲, MERRA2对AOD值较高的站点低估0~0.22. MERRA2在中东地区的再现效果最好,北美和东亚地区效果较差. 2000-2017年AOD最高值在中国的四川盆地、华北平原及长三角地区;其次为印度恒河平原、塔克拉玛干沙漠、非洲和阿拉伯半岛,低值区在北美、南美、澳大利亚、俄罗斯和青藏高原地区.印度及相邻的阿拉伯海域AOD显著增加,增加速率约0.08/10 a.不同季节而言,夏季AOD最大,春季次之,秋季和冬季较小;沙尘AOD最高值为北非的沙漠地区,其次为塔克拉玛干和阿拉伯半岛.印度恒河平原沙尘AOD显著减小,减小速率约0.03/10 a.沙尘AOD呈夏季最大,春季次之,秋冬季较小的特征.

MERRA2 reanalysis data and aerosol robotic network observation data were used to analyze the spatial distribution and trends of global aerosol and dust aerosol optical depth(AOD). The results showed that MERRA2’s AOD was consistent with AERONET observations, the correlation coefficient was between 0.44 and 0.92 and the root mean square error is between 0.03 and 0.52. The sites with a large root mean square error were mostly located in East Asia and stations with AOD<0.2 in North America, Australia, and Europe. MERRA2 was overestimated by 0 to 0.04 for sites with lower AOD values.Stations with higher AOD values were mostly located in East Asia, South America, and Africa. MERRA2 was underestimated by 0 to 0.22 for sites with higher AOD values. MERRA2 performed best in the Middle East and less effectively in North America and East Asia;the highest AOD value in 2000-2017 was in China’s Sichuan Basin, North China Plain and Changjiang River Delta, followed by the Indian Ganges Plain, the Taklimakan Desert, Africa and the Arabian Peninsula. The low value areas of AOD were North America, South America, Australia, Russia and the Tibetan Plateau. AOD had increased significantly in India and adjacent Arab waters, with the increasing rate being about 0.08 per decade. For different seasons, summer AOD was the largest, followed by spring, autumn and winter are smaller;the highest dust AOD was in the desert region of North Africa, followed by Taklimakan and the Arabian Peninsula.The dust AOD of the Ganges plain in India was significantly reduced, the reduction rate being about 0.03 per decade. Dust AOD was the largest in summer, followed by spring, and smaller in autumn and winter.