Arctic Oscillation′s Significance for Prediction of East Asian Summer Monsoon Rainfall

The influence of spring Arctic Oscillation (AO) on the summer rainfall over Meiyu—Changma—Baiu regions is analyzed.Here the precipitation observations for period 1899—1999 for ten stations located in these regions are employed.Results show that on the interannual time scale,the correlation between 10-station-mean precipitation and May AO is -0 45,significant at 99% confidence level.There are about 8% decrease of summer rainfall in association with a one standard deviation stronger AO,and vice versa.The responsible atmospheric circulation displays a north shift of the jet stream.It is also found that the larger anomalies of AO are usually followed by more significant variations of rainfall;whereas,the relations are not evident in the small-AO-anomaly conditions.This is helpful for East Asian summer rainfall prediction.

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