Variation Of The South China Sea Summer Monsoon In Recent 20 Years And Its Relationship With The Change Of Sea Surface Temperature In The Bay Of Bengal

Based on daily sea surface temperature (SST) data which is obtained by the modern high resolution radiometer of the National Oceanic and Atmospheric Administration (NOAA) and wind field, geopotential height field, OLR, which are provided by NCEP/DOE reanalysis datesets, S-EOF, correlation and composite analysis are utilized through the study. Driving the ECHAM5 global atmospheric circulation model for multi-group integrations, we investigated interannual variations of South China Sea summer monsoon and Sea surface temperature anomaly in the Bay of Bengal in recent 20 years. The main conclusions are as follows:(1) Interdecadal change of South China Sea summer monsoon occured in the 1993. The average of the south China sea summer monsoon onset date is May 14 from 1993 to 2012, which is 1 pentad earlier than 1982 to 1992.(2) It is found that the SST anomaly (SSTA) in this area (6°～14°N,85°～95°E) of the Bay of Bengal plays an important role in indicating the onset of the SCS summer monsoon in recent 20 years, which is passing 0.05 significance level. When the SSTAs in the BOB is above (lower) than normal, the SCS summer monsoon will burst earlier (later) than normal.(3) Numerical experiments are conducted using the atmospheric general circulation model ECHAM5 based on observational results. These experiments’ results indicate that the lower (above) SSTA enhances (weakens) the cross-equatorial flows at 80°-100°E, the west side of southern hemisphere Australia negative anomaly circulation increase and then increases (decreases) the westerly, over the SCS resulting in the early (late) onset of SCS summer monsoon.(4) SSTA in this area (6°N-14°N,85°E-98°E) of the Bay of Bengal have a negative correlation with intensity of the SCS summer monsoon in June. The lower (above) SSTA in the area of BOB enhances (weakens) the intensity of SCS summer monsoon.