嘉兴市汛期降水气候分析

对1954至2005年嘉兴汛期降水,包括梅汛期和台汛期降水做滑动平均和小波分析,发现嘉兴汛期梅汛期降水,在降水偏多的50年代和80~90年代都存在着3~4 a周期变化,而台汛期降水存在5 a和9~10 a的周期振荡。台汛期降水在90年代末和21世纪初出现增多现象。汛期梅汛期降水年代际振荡周期有14 a2、0 a,台汛期周期自20 a向36 a转变。对梅汛期台汛期降水分别做降水异常偏多(少)年合成分析,发现影响嘉兴梅汛期降水的主要环流系统是贝加尔湖西风槽和西太平洋副高,欧亚大陆经向(纬向)环流发展,副高偏强(弱),降水偏多(少);8~9月影响嘉兴降水的主要环流系统是西太平洋副高,西太平洋副高偏强(弱),位置偏北(偏东),有(不)利于台风影响嘉兴,从而台汛期降水偏多(少)。

Climate Analysis Of Flood Season Precipitation In JiaXing

Moving average method and wavelet translation method have been used to analyze flood season precipitation,which including Meiyu season precipitation and typhoon season precipitation,in JiaXing from 1954 to 2005.It is found that there is a 3~4 years periodicity of flood season and Meiyu season precipitation in the 1950s and 1980s-to-1990s,while there are 5 years and 9-to-10 years periodicity of the typhoon season precipitation which increased in the late 1990s and at the beginning of the 21th century.The interdecadal periods of Meiyu season are 14 years and 20 years,and the period of typhoon season precipitation shifted from 20 years to 36 years.Compositive analysis shows that the main circumfluence systems which affect Jiaxing's Meiyu precipitation are Baikal lake westerly trough and the West Pacific subtropical high,and the main circumfluence system affecting precipitation of JiaXing from Aug.to Sep.is the West Pacific subtropical high.The development of the meridoinal(zonal) circulation in Eurasia and the stronger(weaker) subtropical high will benefit(disbenefit) the precipitation.Also the Subtropical High is stronger(weaker) and northward(eastward) than the normal will make the typhoon affect JiaXing conveniently(inconveniently),therefore the typhoon season precipitation is above(below) the normal.