摘要
Based on the monthly precipitation data from 43 stations in North China from 1979 to 2008,the variation characteristics of precipitation in North China in recent 30 years were analyzed by means of empirical orthogonal function(EOF)decomposition,Morlet wavelet transform and Mann-Kendall test.The results showed that the spatial distribution of annual and seasonal precipitation was basically identical in North China,while the annual and summer precipitation from the middle of 1980s to the middle of 1990s were obviously more than these in other periods,and there was great annual variation in spring precipitation in 1990s,while autumn precipitation was higher from 1980s to 1990s and then went down after the beginning of 21st century,which was opposite to winter precipitation,namely there was more winter precipitation from 1980s to 1990s and fewer winter precipitation after the beginning of 21st century.In addition,the annual and summer precipitation changed abruptly in 1997,and there was no obvious change in spring precipitation and autumn precipitation,while winter precipitation had an abrupt change in 2000.Meanwhile,wavelet analysis revealed that the variation period of annual and seasonal precipitation was 3-4 years.
Based on the monthly precipitation data from 43 stations in North China from 1979 to 2008,the variation characteristics of precipitation in North China in recent 30 years were analyzed by means of empirical orthogonal function(EOF)decomposition,Morlet wavelet transform and Mann-Kendall test.The results showed that the spatial distribution of annual and seasonal precipitation was basically identical in North China,while the annual and summer precipitation from the middle of 1980s to the middle of 1990s were obviously more than these in other periods,and there was great annual variation in spring precipitation in 1990s,while autumn precipitation was higher from 1980s to 1990s and then went down after the beginning of 21st century,which was opposite to winter precipitation,namely there was more winter precipitation from 1980s to 1990s and fewer winter precipitation after the beginning of 21st century.In addition,the annual and summer precipitation changed abruptly in 1997,and there was no obvious change in spring precipitation and autumn precipitation,while winter precipitation had an abrupt change in 2000.Meanwhile,wavelet analysis revealed that the variation period of annual and seasonal precipitation was 3-4 years.
基金
Supported by National Key Technology R&D Program(2007BAC-29B02)
