Study On Correlations Between Decadal Variability Of Tropical And North Pacific SSTA And That Of Precipitation In China

In this paper, Decadal variability of tropic and north Pacific's SSTA and of precipitation in china, correlations between them and the possible mechanisms of the SSTA decadal change compacting on the precipitation decadal change are analyzed by using NCEP globe temperature, wind and height data( 1948-2001), COADS SSTA data( 1900-2001) and 147 stations' precipitation data in china. Results show that:(1) Mid-high latitude north Pacific and tropic west Pacific SSTA have obvious decadal change, the prior's decadal change has great variance and the latter's has great contribution in total variance, the main eigenvectors' distribution are stable in EOF of tropic and north Pacific SSTA's decadal variability, the key area of the first eigenvector allots in two sides of tropic Pacific; the second one's allots in mid-high latitude northwest Pacific and low latitude mid-east Pacific which vary contrary; the third one's allots in middle north Pacific.(2) Summer precipitation in North China, middle and up valley of ChangJiang River and southeast of China have greater decadal change. The key area of the first eigenvector of EOF for summer precipitation decadal change in china allots in south and north of Changjiang River which vary contrary; the second one's allots in middle valley of ChangJiang River and JiangHuai valley; the third one's allots almost in total china. (3)Tropic and north Pacific summer SSTA's decadal change has good correlation with China summer precipitation's decadal change. Tropic west Pacific is the key area whichinfect precipitation in north of ChangeJiang River greater; Middle north Pacific is the key area compacting precipitation in middle and down ChangJiang River valley and heavier; and middle northwest Pacific-low latitude mid-east Pacific are key areas infecting precipitation in North China more obviously.(4) In summer, tropic west Pacific SSTA decadal change infect precipitation decadal change in south and north of ChangJiang River maybe by: Positive SSTA in tropic west Pacific weaken the summer monsoon circulation, lead more precipitation in south of ChangJiang River and less precipitation in north of it, vice versa; Middle north Pacific SSTA decadal change infect precipitation decadal change in mid-down valley of ChangJiang River maybe by: when SSTA is negative in middle north Pacific, the height field in tropic rises obviously, the subtropical high strengthens and extends westward, the northern limit retreats southward, leads upper trough retreats northward and move eastward, Meiyu front moves northward, then leads more precipitation in mid-down valley of ChangJiang River, vice versa; Middle northwest Pacific-low latitude mid-east Pacific infects precipitation in North China possibly by change the activity of Northeast China cyclone.