兰江流域降雨量与气候指数的相关性研究

Correlation between climate indexes and precipitation of Lanjiang River

为探索兰江流域降雨量与气候指数的关系,利用1963—2000年间兰江流域28个气象站的日降雨量与同期经样条插值的太平洋年代际振荡(PDO)、南方涛动指数(SOI)和东亚夏季风指数(EASMI)日值时间序列,分别采用线性回归和多元回归方法分析兰江流域两大支流的降雨量与PDO和SOI的长期相关性及其与SOI和EASMI的短期相关性.结果表明,PDO与降雨量存在显著的长期正相关关系,其中金华江支流比衢江支流更为显著.在长期尺度上,SOI与降雨量存在负相关,且相关性均大于0.2.在短期尺度上,SOI、EASMI与降雨量均存在显著负相关;作为一种区域指数,EASMI与兰江流域降雨的相关性比其他指数显著,尤其在衢江流域,当PDO位于暖相位时,其相关性系数达到0.5.按照PDO相位划分的子时期评估结果显示,当PDO位于暖相位时,SOI、EASMI与降雨量的相关性都更为显著.多元回归分析证实PDO、SOI及EASMI的相互组合可显著提高其与降雨量的相关关系,特别是PDO-SOI组合,其与降雨量的相关性在金华江和衢江流域分别达到0.39和0.28.

Three climate indexes,including Pacific Decal Oscillation(PDO),Southern Oscillation Index(SOI)and East Asian Summer Monsoon Index(EASMI),interpolated to daily values using spline interpolation method,were analyzed with daily precipitation from 28 meteorological stations over Lanjiang River Basin from 1963 to 2000 in order to investigate the correlation of precipitation and climate indexes.Both linear regression and multiple regression were adopted.The PDO index was investigated for the long-term relationship and the SOI index was investigated for both long and short term.The EASMI was only investigated for short term relationship.Results show that there is significant long-term positive correlation between precipitation and PDO,and the correlation in Jinhua subbasin was more significant than that in Qu subbasin.On long-term correlation,SOI is negatively correlated to precipitation with a correlation coefficient greater than 0.2.For short-term correlation,SOI and EASMI are negatively related to precipitation,and the correlation is more significant for EASMI since it is a regional-based index.Especially for Qu subbasin,a correlation coefficient up to 0.5 is found for EASMI when PDO is in warm phase.According to investigation at different subperiods defined by PDO phases,SOI and EASMI exhibite more significant correlation with PDO in warm phase.Furthermore,multiple regression results show that index combination of SOI,PDO and EASMI can significantly increase the correlation with precipitation,especially the PDO-SOI combination with correlation coefficient up to 0.39 for Jinhua subbasin and 0.28 for Qu subbasin,respectively.