1961-2019年广东前汛期持续性暴雨的变化及前兆信号

Variation and Precursory Signals of Persistent Rainstorm during the First Rainy Season in Guangdong Province from 1961 to 2019

为了提高前汛期降水集中期及雨量的短期气候预测能力,利用小波分析、相关分析等方法研究了近59年广东前汛期持续性暴雨日数的变化特征,探讨了它在前冬大气环流场和海温场上的前兆信号及影响的物理机制。结果表明:(1)近59年广东前汛期持续性暴雨过程108次,总日数398日,主要发生在5-6月,达到或者超过10日的长持续性暴雨过程主要出现在6月。持续性暴雨日数具有准2年、准7年及准12年的周期振荡;(2)前冬大气环流影响持续性暴雨日数异常偏多(少)的前兆信号:500 hPa欧洲(45°N-60°N,0°-30°E)脊(槽)偏强、西亚北部和中亚地区(30°N-50°N,50°E-70°E)及其以北的高空槽(脊)偏强,850 hPa南海北部(18°N-22°N,107°E-120°E)南风偏强(弱),它们主要通过调节后期东亚大槽和南海北部南风的强弱影响前汛期持续性暴雨日数;(3)前冬北太平洋中部(15°N-30°N,170°E-160°W)SST是影响广东前汛期持续性暴雨日数的SST关键区。在4~8年和8~18年尺度上它与广东前汛期持续性暴雨日数具有较好的相反变化关系。它通过影响后期大气环流影响广东前汛期持续性暴雨日数变化。

In order to improve the short-term climate prediction ability of precipitation concentration period and rainfall during the first rainy season in Guangdong Province,the variation characteristics of persistent rainstorm days in recent 59 years,the precursory signals in the atmospheric circulation and SST field in pre-winter,and the physical mechanism were studied by using wavelet analysis,correlation analysis and other methods.The results show that:(1)there were 108 persistent rainstorm processes,and 398 persistent rainstorm days during the first rainy season in Guangdong in recent 59 years.Most of persistent rainstorm processes occurred from May to June,and long-lasting torrential rain reaching or exceeding 10 days mainly occurred in June.The number of persistent rainstorm days exhibited quasi 2-,7-and 12-year periodic oscillations;(2)The precursory signals in prewinter over the atmospheric circulation affecting the more(less)number of persistent rainstorm days were stronger ridge(trough)in European(45°N-60°N,0°-30°E)and stronger trough(ridge)in northwest Asia and mid-Asia(30°N-50°N,50°E-70°E)and its north at 500 hPa,and the stronger(weaker)southerly in northern SCS(18°N-22°N,107°E-120°E)at 850 hPa.They affected the number of persistent rainstorm days in the first rainy season by mainly adjusting the strength of the East Asian Trough and the wind over northern SCS in the later stage.(3)The SST in pre-winter in the central North Pacific(15°N-30°N,170°E-160°W)was the key SST region affecting the number of persistent rainstorm days in the first rainy season in Guangdong Province.They had a good inverse relationship on the periodic scale of 4~8 years and 8~18 years.It affected the number of persistent rainstorm days in the first rainy season in Guangdong Province by influencing the later atmospheric circulation.