嫩江流域夏季降水气候特征及前兆信号分析

Analysis on climate characteristics and the precursor signal of summer precipitation in Nenjiang Basin

利用1961—2013年嫩江流域31个气象观测站的逐日降水资料和NCEP再分析资料,结合相关分析、合成分析等数理统计方法,分析了嫩江流域夏季降水气候特征及前兆信号。结果发现,嫩江流域夏季降水存在着准25 a和5-7 a的周期变化;嫩江暴雨频次对其夏季降水有着非常显著的影响;前期的大气环流和海温的异常对嫩江流域夏季降水异常有重要作用,秋末冬初北半球500 h Pa环流出现NAO正(负)位相,有利于翌年嫩江流域夏季降水偏多(少);夏季发展(衰减)的东部型El Nino事件,有利于翌年嫩江流域夏季降水偏多(少);春季乌拉尔山东部、黑海和里海附近积雪偏多(少)有利于嫩江流域夏季降水偏多(少)。

Daily precipitation data and NCEP reanalysis data of 31 meteorological stations in Nenjiang basin from 1961 to 2013 was used to analyze the climate characteristics and the precursor signal of summer precipitation with the statistical methods such as synthesis analysis and correlation analysis. The results show that there is a periodic variation of quasi 25 a and 5-7 a in the summer precipitation in Nenjiang basin, and the frequency of heavy rain has significant effects on the summer precipitation. The anomalous atmospheric circulation and sea surface temperature play an important role in the summer rainfall anomalies in the Nenjiang River Basin,The oc- currence of NAO positive （negative） phase in the 500 hPa circulation in northern hemisphere autumn and winter is prone to cause more （less） precipitation in the Nenjiang River Basin in next year summer.The developing （w in eakening） Eastern E1 Nino events are advantageous to the more （less） summer precipitation in Nenjiang Basin the next year. At the same time, more （less）snow accumulation in the eastern part of Ural Mountain and the Black Sea and the Caspian Sea is in favor of the more （less） summer precipitation.