Relationship Between Indian Ocean Sea Surface Temperature Dipole Oscillation And The East Asian Atmospheric Circulation And Precipitation

Based on spring and summer precipitation in China and the Indian Ocean sea surface temperature anomaly (SSTA) of English from 1951 to 2000 and NCEP data from 1951 to 2000, by using EOF and composite analysis and correlation analysis and singular value decomposition (SVD) methods and so on, In the IOD developing term, from the Indian Ocean STA unusual distribution, unusual circulation characteristic of Eurasia and correlate with Indian Ocean Dipole index, China summer unusual rainfall distribution and correlate with Indian Ocean Dipole index , diagnosis analysis of the unusual circulation four respects research the effect of the Indian Ocean Dipole (IOD) on East Asia atmospheric circulation and precipitation. The results as follows: (1) When the IOD developing, the Indian Ocean sea surface temperature anomaly always changes from west to east, the SSTA varieties of IO develop firstly from the West Indian Ocean, in positive years the West Indian Ocean ST is being apart from the even strength to strengthen and the scope extension continuously slow moves toward east, the southeast IO takes to be apart from the even increment and scopes to contract gradually, vice versa. (2) IOD positive years, in mid-highs latitude, averaged ridge and trough are stronger, near ground levers cold high system in Siberia is stronger than that of usually year, be advantageous to cold air's go down south, the south of China is controlled by the unusually north wind. In summer the high anomalous of 500 hPa in East Asia presents the south high and north low , the West Pacific subtropical high is southerner and westerner and stronger, from the east of North China go to Japanese whole be placed in the control of the excrescent anti- cyclonic in summer, South China be controlled by southwest current which lying in the northwest of excrescent anti-cyclonic. Negative IOD years, in the season that winter converts to the summer, averaged ridge and trough of 500 hPa die down to compare quickly, the strength weaker than usual year, in summer the high anomalous of 500 hPa in East Asia presents the south low and north high, the West Pacific subtropical high is northerner and easterner and weaker, below 500 hPa layer west Pacific regions exist abnormal cyclonic, sea surface east to Japan has excrescent anti- cyclonic , cyclonic is more than usual in north China, in the mid China and central part of the take on anomalous wind convergence, rainfall is more in north of Chinese. (3)Correlation coefficient between IODI and rainfall of China can express real rainfall distribution, so IODI can be look as the signal which could predict anomaly rainfall. SVD analysis show IO SSTA influence on rainfall of China. When IO SSTA is positive (negative), rainfall is more (less) over South China, anomalous rainfall is significant in SW China and central of Yangtze river. When West IO SSTA is positive and Southeast IO SSTA is negative, South China rainfall is more and precipitation is less in Southwest and mid- and up-reaches of Changjiang River of china, vice versa. (4) Positive IOD years, the convective activity over Philippines is weaker, and also the Walker circulation over IO, the Hadley circulation over East Asia. In summer, precipitation is more in South China and less in Southwest and central of China, vice versa..