摘要:本文利用NCEP/NCAR再分析资料和中国2374站日降水资料，通过水汽收支方程分解方法分析了华南夏季降水在1993~2002年时段年代际增多以及2003~2013年时段年代际减少的水汽输送特征及其成因。结果表明：1993~2002年时段（2003~2013年时段），局地环流导致异常下沉（上升）气流，南亚高压偏东（偏西）和西太平洋副热带高压（简称副高）偏西（偏东），菲律宾及副高西南侧水汽输送加强（减弱），华南地区低层出现强的水汽辐合（辐散），导致降水偏多（偏少）。华南地区夏季降水两次年代际变化主要与风速变化引起的水汽输送动力散度项的异常有关，同时还受到与比湿变化引起的水汽输送热力散度项异常、及天气尺度的涡旋引起的水汽输送涡流散度项异常影响。此外，研究发现水汽输送的异常与环流和海温异常均密切相关。
关键词:华南夏季降水/
年代际转折/
水汽收支方程/
大气环流/
海表温度
Abstract:Based on the reanalysis data provided by the National Centers for Environmental Prediction/National Center for Atmospheric Research and the daily rainfall data obtained at 2374 stations by the China Meteorological Administration, the precipitation moisture transport was found to have increased during the 1993–2002 period and decreased during the 2003–2012 period over South China. In this study, the characteristics of this precipitation transport were compared using a moisture transport budget equation, and the reason for the two decadal changes in the summer precipitation in South China was determined. Our results show that the increase (decrease) in summer precipitation during the 1993–2002 (2003–2013) period in South China was mainly influenced by the local circulation of the vertical air stream, eastward (westward) movement of the South Asia high, and the westward (eastward) extension of the West Pacific subtropical high (WPSH), which resulted in a strengthening (weakening) of the moisture transport from the Philippines and the southwest side of the WPSH and a strong convergence (divergence) of moisture in the lower layer over South China. The interdecadal variation of the summer precipitation of South China is mainly related to anomalies in the dynamic divergence of the moisture transport caused by changes in wind speed. It is also affected by an anomaly of the thermodynamic divergence of the moisture transport caused by a change in the specific humidity and an anomaly in the subseasonal-scale eddies generated by synoptic-scale eddies. In addition, we found the moisture transport anomalies to be closely related to the circulation and sea-surface-temperature anomalies.
Key words:Summer precipitation in South China/
Interdecadal change/
Moisture budget equation/
Atmospheric circulation/
Sea surface temperatures (SST)
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