HR: 1340h
AN: H33B-1391    [Abstracts]
TI: The Relationship between East Asian Summer Monsoon and ENSO Cycle and Its Impact on Summer Rainfall in Southeast China
AU: * Cai, X
EM: cai4849@yahoo.com.cn
AF: Meteorological Observatory of Fujian , 108 Wushan Road, Fuzhou, FJ 350001 China
AB: Based on NCEP wind data at 850hPa and OLR data, different features of the East Asian summer monsoon and the Western Pacific Subtropical High (WPSH) during dry summer and wet summer in Southeast China are discussed. The main results are as follows: In the East Asian summer monsoon system, the tropical monsoon circulation strengthens (weakens) while the subtropical monsoon circulation weakens (strengthens) and mid-high latitude monsoon circulation strengthens (weakens) in wet (dry) summer. In wind vector field at 850hPa, there is an anomalous anticyclone (cyclone) to the east of Japan while an anomalous cyclone (anticyclone) over Southeast China and another one over the sea of Okhotsk in wet (dry) summer. Correspondingly, there are positive (negative) OLR anomaly centers in the areas of the anomalous anticyclone (cyclone) mentioned above. Results also show that there is a northward (southward)-slanted average location of the WPSH in wet (dry) summer. During the seasonal transition from spring to summer and from summer to autumn, the seasonal northward and southward jumps of the high ridge in wet years are quicker, inversely the jumps in dry years are slower. Analysis result showed that there exists a 500hPa height anomaly pattern over East Asia and the Pacific in wet (dry) summer, which means that there is not blocking situation over the Sea of Okhotsk and the Western Pacific Subtropical High is to the north of its mean location in wet summer when the subtropical frontal zone locates northward, while there is a blocking situation over East Asia when the subtropical frontal zone locates southward in dry summer. Accordingly, an East Asian Atmosphere Teleconnection Pattern Intensity Index (Iea) was defined. By further examining the atmosphere and ocean features when Iea was abnormal, it is found that ENSO cycle has distinct phase features before abnormal atmospheric teleconnection occurring. In the strong (weak) atmospheric teleconnection years, the equatorial central-eastern Pacific and its vicinity is controlled by warm (cold) water and the westerly drift zone is distributed by negative (positive) SST anomalies in general. Especially, in last winter the direction of 200hPa U component anomalies in the vicinity of the equatorial central Pacific is opposite to that of its both sides in tropical Pacific. The 200hPa U component anomalies over the most different areas, i.e. 160°- 120°W of the equatorial central-eastern Pacific and the tropical Pacific (25°S , 30°N) can be regarded as a signal foretelling abnormal atmospheric teleconnection in summer.
DE: 1640 Remote sensing (1855)
DE: 1812 Drought
DE: 1833 Hydroclimatology
DE: 1869 Stochastic hydrology
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
SC: Hydrology [H]
MN: Fall Meeting 2005