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本文基于南海地区850 hPa风场,降水以及海温定义了南海夏季风爆发指数,将南海季风爆发过程分为季节转换和季风爆发两个过程来进行研究。对18年的观测分析发现,南海季风爆发可归纳为三种情况:第一种是季风正常爆发,随着季节转换结束后,西南季风和降水在南海地区有明显增强;第二种是间接性爆发,在季节转换结束后,西南季风和降水的建立不是特别明显;第三种是推迟爆发,在季节转换结束后,南海地区没有建立西南季风也没有降水产生。进一步研究发现,西太副高异常西伸是导致南海季风延迟爆发的重要因素之一。此外,大尺度环流背景ENSO的影响也对南海季风爆发时间的早晚有重要影响,但并不是唯一决定性因素,印度洋和亚洲大地形的局地热力差异变化是影响季风爆发的另一重要因素。
Based on the 850 hPa wind field, precipitation and SST in the South China Sea, the SCS summer monsoon onset index is defined and the South China Sea monsoon onset process is divided into two processes, the seasonal transition and the monsoon onset. According to 18-year observation and analysis, it is found that the monsoon onset in the South China Sea can be summarized into three situations: the first is a normal monsoon outbreak, and the southwest monsoon and precipitation are obviously enhanced in the South China Sea after the seasonal change; the second is indirect After the seasonal transition, the establishment of the southwest monsoon and precipitation is not particularly obvious. The third one is the postponement of the outbreak. After the end of the season, no southwester monsoon and no precipitation have been established in the South China Sea. Further study found that the anomalous extension of the West Pacific subtropical high is one of the important factors leading to the delayed onset of the South China Sea monsoon. In addition, the impact of the large-scale circulation background ENSO also has an important influence on the onset time of the South China Sea monsoon, but it is not the only decisive factor. The variation of local thermal differences between the Indian Ocean and the Asian large terrain is another important factor affecting the monsoon onset.