Vortex Merging Process In The Numerical Study Of The Double Vortex. Vortex Group Merger And Meiyu

Typhoon and storm rainfall is two types of China's representative meteorological disasters. Presently many achievements have been gained in the track of typhoon and the forecast of typhoon. It is accurate to forecast normal typhoon, but there are many difficulties in the forecast of enhanced typhoon suddenly. Currently many meaningful research on typhoon have been done by domestic and foreign meteorologists and a lot of meaningful results have been achieved. However, due to the complexity of the inner structure of typhoon and the outer surroundings, the cause and the mechanism of typhoon enhanced suddenly have not been known completely today and the further research on the law of the evolutive process of typhoon is needed. At present lots of meteorologists pay attention to the reseaches about Meiyu occurred in Jianghuai and have made large qualities of successful pursuits. Because of the complicacy itself, we cannot understand distinctly the rule of it. It is worthy of doing substantive investigations.Owing to vortex merger has consanguineous association with typhoon and rainfall, in the frame of the vortex self-organization dynamics the question of the interaction between double vortices is investigated by using numerical model and the differences and homogeneities of double vortices interaction under the two types of conditions involving weak outer fields and swarms of vortices as ambient flow is contrasted. It is shown that the merger process of the double vortices in the case of weak ambient fields doesn't exist under the circumstances of groups of vortices, in the meanwhile, the introduction of swarms of vortices can make vortex intensify.Because the merging of cloud group is consistent with that of vortices, the merging of cloud group or vortices may be important in the cause of the center of the heavy rainfall. A heavy rainfall occurred in Jianghuai during 8-9July 2003 .The above-mentioned case has been analyzed using the reanalyzed data 4 times a day from NCEP including wind, humidity and height fields. The results show that the heavy rainfall was mainly associated with the mesoscale vortices merger. It was noticed that relative vorticity, divergence, vertical velocity, the delivering of the moisture, and moist spiral divergence were strengthened. It was shown that the Bengal Bay and the South China Sea may be the important moisture source place. It was emphasized that lower levels convergence and higher levels divergence was important of the maintenance of the heavy ascending motion and the convective systems were benefited from the heavy ascending air.