| Based on observed SST data of several fixed stations and observed air temperature data from weather stations,analyze the character and tendency of SST variation in the coastal region of south china,the relation between SST variation and El Nino / La Nino,and especially analyze the variation,difference and reason of the SST in the Zhujiang River estuary during the El Nino events in 1982/1983 and 1997/1998----the two strongest El Nino events in the twentieth century;analyze the relation between SST variation and red-tide,and especially analyze the characteristic of SST change and the reasons of the abnormally high SST in Guangdong coastal sea area during the large scale red tide occurred in Guangdong and Hong Kong in the winter-spring of 1998;analyze the characteristic of SST change in Guangdong coastal sea area during the rare cold disaster happened in the middle ten days of January to February 2008.The results show tha Each month,the regional disparity of SST is 1℃～3.4℃,and the SST annual range is 11.6～12.5℃.The seasonal variation of SST correlates with the global warming significantly,the monthly and yearly averaged SST have rising,There is a notable upward tendency during 1960 and 2007,with a linear slope of 0.311℃/10a～0.131℃/10a,the rising extents in winter are higher than those in summer.The variabihty in winter is bigger than that in summer,with the biggest in February and March.A wavelet multi-resolution method was used to analyze period characteristics of SST in CRSC.All time-scale decomposition series are very similar.The SST has obviously 3～4a periods besides natural periods. Rising trends of SST since the mid-1970 continued to this day.The afect to the SST change by the El Nino/La Nino is not a single coincidence relation,the reason caused the difference is that the solar total irradiance reached the ground in 1982/1983 is higher than that of 1997/1998;The high pressure of the South Sea in 1982/1983 is weaker than that of in 1997/1998;The winter wind speed in 1982/1983 is 1m/s～2m/s faster than that of in 1997/1998.In the recent 20 years,the monthly SST was remarkably ascending trend in spring,and the monthly mean SST linear slope is 0.16℃/10a～0.10℃/10a.When red-tide occurred,the range of SST ascended month by month,as in March,it's 16℃～23℃,18℃～27℃in April and 23℃～29℃in May.During the large scale red tide occurred in Guangdong and Hong Kong in the winter-spring of 1998,the monthly mean SST change trend is quasi-synchronous,the quarterly mean SSTA of every station is 1.1℃～1.5℃,which up to the standard of abnormally high SST,and the monthly mean SSTA is 1.5℃～2.0℃.There are two obvious peaks of SSTA happened from Dec.to Jan.and Apr.to May.The main reasons of this abnormally high SST are global warming,strong El Nino,unusually winter monsoon and the lasting strong South China Sea high pressure.The large-scale cold disaster in the middle ten days of January to February 2008 had such Characteristics as wide influence area,great intensity,long duration, low average air temperature,more rain and few sunling hours,and big influence,etc. The mean SSTA is lowest in the latest 50 years,low SST is long duration and the regional disparity of SST Variation is distinct during the rare cold disaster.
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