林爱兰, 梁建茵, 李春晖, 谷德军, 郑彬. “0506”华南持续性暴雨的季风环流背景[J]. 水科学进展, 2007, 18(3): 424-432.
引用本文: 林爱兰, 梁建茵, 李春晖, 谷德军, 郑彬. “0506”华南持续性暴雨的季风环流背景[J]. 水科学进展, 2007, 18(3): 424-432.
LIN Ai-lan, LIANG Jian-yin, LI Chun-hui, GU De-jun, ZHENG Bin. Monsoon circulation background of ‘0506' continuous rainstorm in South China[J]. Advances in Water Science, 2007, 18(3): 424-432.
Citation: LIN Ai-lan, LIANG Jian-yin, LI Chun-hui, GU De-jun, ZHENG Bin. Monsoon circulation background of ‘0506' continuous rainstorm in South China[J]. Advances in Water Science, 2007, 18(3): 424-432.

“0506”华南持续性暴雨的季风环流背景

Monsoon circulation background of ‘0506' continuous rainstorm in South China

  • 摘要: 提出了确定东亚夏季风活动区域、划分热带季风和副热带季风活动区域的指标,利用大气对流层风速、位势高度、湿度、温度、OLR以及TBB等NCEP/NCAR资料,从月、候和过程平均多种时间尺度,诊断分析了2005年6月(简称“0506”)华南持续性暴雨的季风环流活动变化特征.结果表明:副热带高压强度偏强,西脊点位置偏西偏南,热带西太平洋(130°~140°E)区域越赤道气流偏强,华南处于气旋性低压异常区,无论是月时间尺度还是暴雨过程时间尺度都表现出这些明显特征;暴雨过程水汽除了来源于孟加拉湾和南海外,水汽通量异常部分主要来自南海和热带西太平洋,热带西太平洋水汽随着副高边缘气流经过南海向华南输送,从而为暴雨过程提供了丰富的水汽来源;2005年6月热带季风前沿在华南沿海地区停滞时间比气候平均偏长(2候),该特征是华南暴雨预报值得参考的信号;6月整个南海地区平均季风偏强,主要体现于经向风明显偏强,但华南持续性暴雨过程开始于南海地区夏季风非活跃期,这与热带季风季节内振荡向北传播到华南有关.以上季风活动变化特征为华南强降水提供了有利的动力条件和丰富的水汽来源.

     

    Abstract: The indexes are advanced to decide the summer monsoon extent of East Asia and identify the activie region of the tropical and subtropical summer monsoon.By using the NCEP/NCAR troposphere data of wind,geopotential height,humidity,temperature,the satellite-derived OLR and TBB,the activity and variability characteristics of the monsoon circulation during ‘0506' continuous rainstorm are diagnosed from monthly,pentad and the process time scales.The results indicate that if the subtropical anticyclone is stronger,the west-point of subtropical anticyclone ridge is more farther westward and southward than the climatological average,and the cross-equatorial stream in tropical western Pacific(130-140°E) is stronger.South China is located in a region of the anomalous cyclonic depression.These characteristics are exhibited in either monthly or rainstorm process time scale.Besides the Bay of Bengal and South China sea,the water vapor of the rainstorm process is mainly from the abnormal water vapor flux over the South China sea and the tropical western Pacific.The water vapor in the tropical western Pacific transports to South China following the stream at the edge of the subtropical anticyclone via the South China sea.Consequently,plentiful water vapor is provided during the rainstorm process.The front part of tropical summer monsoon stagnates for two pentads longer than the climatological average.This characteristic is a valuable signal for forecasting South China rainstorms.The mean monsoon strength over the South China sea in J une is stronger,which is showed by the stronger meridional wind.But the rainstorm process begins in the period of inactive summer monsoon over the South China sea,which is related to the northward spread of the tropical intraseasonal oscillation.The activity and variability characteristics of monsoon mentioned above act as favorable dynamic condition and the abundant water vapor sources.

     

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