夏季中低纬低频波的活动特征和驱动机制

FEATURES AND DRIVING MECHANISM OF MID-LOW LF WAVE IN SUMMER

利用1984年夏季ECMWF/WMO资料分析了低频涡度系统和低频辐散环流系统,讨论了两者之间的相互作用。结果表明西太平洋和南印度洋上的低频涡旋具有对流性天气系统的三维环流特征,低频速度势场在上述两区域表现为最大的辐合辐散强度和最宽广的辐合辐散区,低频散度波的能量频散激发和驱使印度洋至西太平洋区域内辐散环流呈现明显的准40天振荡。

The present paper gives an analysis of the low frequency (LF) vortex and divergent circulation systems and their interactions in terms of the ECMWF/WMO data (summer of 1984). Results show that the LF vortex in West Pacific and South Indian Ocean have the characteristics of the three-dimensional circulation of the convective synoptic system and ,the divergent/convergent intensity of the LF velocity potential field is the strongest and the divergent/convergent area is the widest in the above-mentioned regions. The energy disperse of LF divergent wave stimulates the divergent circulation from Indian Ocean to West Pacific to produce a conspicuous quasi-40-day oscillation.