北半球夏季风区大气视热源和视水汽汇的低频振荡

利用１９８６年５－９月ＥＣＭＷＦ／ＷＭＯ资料计算非洲季风区、印度季风区、南海季风区和副热季风区的视热源和视水汽汇。结果表明非洲季风区和印度季风区Ｑ１、Ｑ２的准４０天周期显著；南海季风区准双周振荡明显；副热带季风区盛行８天左右的周期；准４０天周期振荡也是南海季风区和副热带季风区的重要信号，印度季风区Ｑ１，Ｑ２的准４０天周期振荡比其他季风区的更为显著；非洲季风区Ｑ１振荡位相超前于Ｑ２振荡位相，其他季风

LOW-FREQUENCY OSCILLATIONS OF THE APPAKENT HEAT SOURCE ANDMOISTUKE SINK OVER NORTHERN SUMMEKMONSOONAREAS

The apparent heat sotirce(Q_1)and apparent moisture sink(Q_2)over African mon-soon area(AMA),Indian monsoon area(IMA),South China Sea monsoon area(SCSMA)andsubtropical monsoon area(SMA)have been calculated.based on ECMWF/WMO data fromMay to September of 1986.The results show that quasi-40-day periods of Q_1 and Q_2 over bothAMA and IMA,quasi biweekly over SCSMA and about 8-day of Q_1 and Q_2 over SMA,quasi-40-day period are also important signals over SCSMA and SMA. Quasi-40-day oscillations ofQ_1 and Q_2 over IMA are much stronger than those over the others, The oscillation phase of Q_1is ahead of that of Q_2 over AMA,but with a homophase for Q_1 and Q_2 over other monsoon ar-eas. The dipole distribution of low frequency oscillations of Q_2 and zonal wind in the low tro-posphere is found over IMA and SCSMA. The low frequency component of Q_2 corresponds tolatent heat source(sink),or apparent moisture sink(source)as the low frequency monsoonbecomes active(inactive)over the monsoon areas.