南海夏季风强弱年环流形势与热带对流特点对比分析

Comparative analysis of tropical convection feature and strong weak cases of south china summer monsoon circulation

利用NCEP/NCAR(美国国家环境预报中心/国家大气研究中心)再分析资料,对南海强夏季风年和弱夏季风年进行合成分析,结果表明,无论是在夏季风爆发前的1月份或是夏季风盛行的7月份,强弱夏季风年的平均经圈环流和平均纬圈环流都有明显差异。在强夏季风年,1月份的哈特莱环流、7月份的瓦克环流和季风经圈环流都比弱夏季风年同期的明显。强夏季风年的西太平洋副热带高压比弱夏季风年明显偏弱。利用OLR资料分析强夏季风年(1981年)和弱夏季风年(1983)4～9月份赤道东印度洋和南海对流活动的季节内振荡,发现在南海强夏季风年,季节内振荡的次数偏少而强度偏强,在弱夏季风年,季节内振荡的次数偏多而强度偏弱。相比之下,在南海强夏季风年,赤道东印度洋的季节内振荡比南海的更具典型性。

Strong and weak summer monsoon years over south china sea were Synthesis analysed by employing NCEP/NCAR data, result indicated that whether in forthcoming of the onset of summer monsoon of January or in prevailing summer monsoon of July, the mean meridional circulation and mean zonal circulation in the strong and weak summer monsoon cases is obvious difference. In strong summer monsoon cases, January Hadley circulation and July walker circulation as well as monsoon meridional circulation are stronger than that of weak monsoon cases. The intensity of Western pacific subtropical high in strong summer monsoon cases is weaker than that of weak summer monsoon years. The OLR data were undertaken to analyse interseasonal variability over equatorial eastern Indian ocean and south china sea in stronger summer monsoon year(1981) and weak summer monsoon year(1983) from April through September, respectively. The outcome showed that in strong summer monsoon cases, the times of interseasonal variability is low and the intensity is quite strong, on the contrary, the times of interseasonal variability is high and the intensity is quite weak in weak summer monsoon cases. Compare with South China Sea, the interseasonal variability of equatorial eastern Indian summer monsoon is more typical than that of SCS in SCS strong summer monsoon years.