热带大气50—40天振荡对亚洲夏季风影响的数值研究

A NUMERICAL STUDY FOR THE EFFECF OF TROPICAL 40-50 DAY OSCILLATION ON ASIAN SUMMER MONSOON

本文利用p—σ混合坐标系的五层原始方程模式,研究了印度洋—西太平洋热带偶极子型振荡对流加热源对亚洲夏季环流的影响。试验结果表明印度洋—西太平洋热带振荡源可以引起赤道东—西纬向环流、越赤道气流、季风经向环流以及亚洲夏季高、低层环流的位相振荡,其振荡周期与振荡热源的振荡周期一致。本文还进一步研究了热带振荡源影响亚洲夏季风环流的机制,研究表明振荡热源西侧激发的Rossby波的西传和扰动的北传、引起赤道东—西纬向环流和季风经向环流的振荡,从而最终导致整个亚洲夏季风环流振荡的机制。

By using a five-layer primitive equation model with P-sigma coordinates, the effect of convective heating source with the oscillation of a dipole pattern over the tropical Indian Ocean- western Pacific on Asian summer monsoon is inver-stigated. The results from simulations show that the oscillatory heating source may cause oscillations in east-west zonal circulation at the quator, in cross-equatorial flow, in meridional monsoon circulation and in the phase of high-low level circulation over Asia, with same period as that of the oscillating heat source. Furthermore, the influence mechanism of the tropical heating source associated with oscillations on Asian summer monsoon circulation is also studied. It is clearly shown that the westward propagation of thermally-forced Rossdy waves to the west of the oscillatory heating source and the northward propagation of disturbances can give rise to oscillations of the equatorial east-west zonal circulation and monsoonal meridional circulation, Finally, the oscillation of all the Asian summer monsoon circulation is formed.