通过利用1958—2007年SODA月平均海温资料、1958—2008年NCEP/NCAR再分析资料以及1974—2008年NOAA卫星月平均OLR资料, 分析了南海季风与南海上层海洋热含量之间的可能关系, 发现南海夏季风爆发早晚与前冬南海上层海洋热含量存在显著的负相关, 即当冬季南海上层海洋热含量偏高(低)时, 次年南海夏季风爆发早(晚)。进一步对南海夏季风爆发异常年前期及前冬南海东部热含量异常年的相关大气环流特征分析后发现, 南海夏季风爆发偏早和偏晚年前期的OLR特征、对流层环流特征及位势高度场分别与前冬南海东部热含量异常偏高和偏低年相一致。得出冬季南海东部热含量偏高(低)时, OLR在赤道东印度洋至我国南海及菲律宾以东为负(正)距平, 南海地区对流加强(减弱); 在纬向方向上, 大气环流特征表现为正(负)的Walker距平环流, 低纬Walker环流发展(减弱); 在经向方向上, 南海地区南北向局地Hadley环流加强(减弱); 次年初春(3—4月)500hPa位势高度场在西太平洋副热带高压区总体为负(正)距平, 副热带高压偏弱(强)。因此有(不)利于南海夏季风的早爆发。南海和西太平洋暖池区热含量异常都通过对流作用影响其上空大尺度环流异常, 与南海夏季风爆发时间呈反相关。不同之处在于南海热含量异常可能激发南北向局地Hadley环流异常, 促进或抑制西南季风向北延伸, 从而影响南海夏季风的爆发时间。
In this paper, various datasets are used to analyze the relationship between the South China Sea summer monsoon (SCSSM) and the SCS upper-ocean heat content (SCSHC). These datasets include SODA ( Simple Ocean Data Assimilation) monthly-mean ocean temperature from 1958 to 2007, NCEP / NCAR reanalysis monthly-mean data from 1958 to 2008, and monthly-mean OLR (Outgoing Longwave Radiation) data from NOAA satellites from 1974 to 2008. It is found that the onset of the SCSSM is negatively correlated to the SCSHC in the previous winter, i.e., the anomalously high (low) SCSHC in winter is corresponding to the early (late) outbreak of SCSSM in the following year. It is also found that the characteristics of OLR, geopotential height, and atmospheric circulation during the previous winter are consistent with the SCSHC. When the SCSHC is higher (lower) in winter, the OLR over regions from the eastern equatorial Indian Ocean to the SCS and the east of Philippines shows a negative (positive) anomaly, and the atmospheric circulation is characterized by positive (negative) anomaly of he Walker circulation and the Hadley circulation. In the following early spring (March - April), the geopotential height at 500 hPa shows negative (positive) anomaly over the western Pacific Ocean (WPO), indicating that the subtropical high is weakened (strengthened) that is favorable (unfavorable) for the early outbreak of the SCSSM. The SCS and the WPO warm pool heat content anomalies could lead to large-scale circulation anomalies over the region through convection activities, which further influence the SCSSM onset. The difference in affecting the SCSSM onset between SCS and WPO is that the SCSHC anomalies may stimulate locally the Hadley circulation anomalies through convection, which will inhibit the northward extension of the southwesterly monsoon and affect the outbreak of the SCSSM.
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