A NUMERICAL STUDY FOR THE EFFECT OF TROPICAL 40—50 DAY OSCILLATION ON ASIAN SUMMER MONSOON

【摘要】 <正> By using a five-layer primitive equation model with P-sigma coordinates, the effect of convective heatingsource with the oscillation of a dipole pattern over the tropical Indian Ocean-Western Pacific on Asian sum-mer monsoon is investigated. The results from simulations show that the oscillatary heating source maycause oscillations in east-west zonal circulation at the equator, in cross-equatorial flow, in meridionalmonsoon circulation and in the phase of high-low level circulation over Asia, with period same as that ofthe oscillating heat source. Furthermore, the influence mechanism of the tropical heating source associatedwith oscillations on Asian summer monsoon circulation is also studicd. It is clearly shown that the west-ward propagation of thermally-forced Rossy waves to the west of the oscillatary heating source and thenorthward propagation of disturbances can give rise to oscillations of the equatorial east-west zonal circula-tion and monsoonal meridional circulation. Finally, the oscillation of all the Asian summer monsoon cir-culation is formed.更多还原

【Abstract】 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 sum- mer monsoon is investigated. The results from simulations show that the oscillatary heating source may cause oscillations in east-west zonal circulation at the equator, in cross-equatorial flow, in meridional monsoon circulation and in the phase of high-low level circulation over Asia, with period same 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 studicd. It is clearly shown that the west- ward propagation of thermally-forced Rossy waves to the west of the oscillatary heating source and the northward propagation of disturbances can give rise to oscillations of the equatorial east-west zonal circula- tion and monsoonal meridional circulation. Finally, the oscillation of all the Asian summer monsoon cir- culation is formed.更多还原