高分辨率卫星实测资料揭示的近年亚洲热带夏季风爆发进程

利用高分辨率卫星观测资料,从气候态角度分析了亚洲热带夏季风爆发特征。研究表明,亚洲热带夏季风最先在中南半岛西部爆发,随后在整个中南半岛和孟加拉湾东部,然后扩大至孟加拉湾西部和南海。夏季风爆发后,与孟加拉湾和南海相比,中南半岛雨量增强形势不明显。第26—28候（即5月第2候—5月第4候）是亚洲热带夏季风的爆发阶段。整个爆发过程,低层风场的时空演变与对流降水相对应,海表温度场增温较海表风场提早约1候左右;华南地区以锋面降水为主,即副热带季风降水。采用对流降水和海表上空10 m风场分别代表夏季风降水和盛行风向的时空演变特征较常规资料更为准确、精细。

Features of the Tropical Asian Summer Monsoon Onset in Recent Years Revealed by High-Resolution Satellite Observations

High-resolution satellite data are used to analyze the features of the onset process of the tropical Asian summer monsoon （TASM） from the point of the climatology view. It is found that the TASM onsets first over the western region of Indo-China Peninsula, next the whole area of Indo-China Peninsula and the eastern part of Bay of Bengal,and then all Bay of Bengal and South China Sea. However, the enhanced rainfall tendency in Indo-China Peninsula is not more obvious than that in Bay of Bengal and South China Sea after the summer monsoon onset. The 26th to 28th pentad（ the first pentad to the fourth pentad of May） is the period of onset process of TASM, during which, the spatio-temporal evolution of low lever wind field corresponds well with convective precipitation, while the sea surface temperature warms one pentad ahead compared to the sea surface wind changing. Mean while, the precipitation of South China is mainly frontal precipitation, named the subtropical monsoon precipitation. The result also demonstrated that using convective precipitation and 10 meters wind field above the sea surface to represent the spatio-temporal evolution of rainfall and prevailing wind of summer monsoon respectively is more accurate and more precise than those routine data.