A Simulation Study Of The Influence Of Marine Characteristics On The Track And Intensity Of Jiang-Huai Cyclones In April

In this paper, in the context of the mesoscale WRF mode and the NCEP/NCAR reanalysis data, three representative Jiang-Huai cyclones in April were simulated by choosing the appropriate parameterizing schemes. Results correctly reflected the real Jiang-Huai cyclones track trends and cyclone intensity trends. The parameterizing scheme of the text had a good reliability to simulate Jiang-Huai cyclones in April. On this basis, sensitivity tests on marine properties and sea surface temperatures were designed. It discussed the sea characteristics'influence on the path and the strength of the Jiang-Huai cyclones with the area of Jiang-Huai cyclones over sea in April.The marine sensitive tests reflected the influence on Jiang-Huai cyclones of the ocean property into the land property under the marine pollution,in which, three aspects of marine attribute were discussed, i.e., the real ocean, the coastal ocean property into land property and the marine property in simulated area into land property.Results showed that:the change of the ocean property make Jiang-Huai cyclones to move southerly and to weaken.The SST sensitive tests reflected the influence on Jiang-Huai cyclones of the different spatial distributions of SST. By using the SST data from hadlSST during April in 1950-2009 in offshore,it got the space of two major SST spatial distributions on the basis of EOF analysis. The first mode of SST variation was the SST consistent distribution type; The second mode was the SST opposite distribution type between the north and south in offshore. Therefore, the SST distribution types could be devided as follows:consistent cold type, consistent calefactive type, south warm-north cold type,and south cold-north warm type. In the sensitive studies, the climatological SST was used as a reference background. When SST distribution types showed consistent calefactive type or south warm -north cold type,it was more advantageous to the development of Jiang-Huai cyclones, and its tracks was more northward; the influence of consistent calefactive type appeared to be larger. When SST distribution types showed consistent slants cold type or south cold -north warm type,it was less advantageous to the development of Jiang-Huai cyclones, and its tracks was more southward; the influence of consistent cold type seemed to be larger.The mechanism were also investigated by analyzing the vertical circulation field, the vapor flux, water vapor flux divergence, convective available potential energy and latent heat fields among the results of sensitive experiments. In vertical circulation, the (800 hPa-600 hPa)southerly flow was conducive to the development of Jiang-Huai cyclones, and increased the cyclone's northly moving component force; while the low-level northerly flow was suppressing the development of Jiang-Huai cyclones, and increased cyclone's southly moving component force; When Jiang-Huai cyclones were near the Da-Bie Mountains,the primary direction of moisture flux was southwest, whereas the location of Jiang-Huai cyclones were over sea, the direction was southeast.That was the moisture convergence at the front of cyclones center,which make the cyclone develop. The low-level (1000 hPa-700 hPa) convective available potential energy in front of the cyclones center was more conducive to the development of cyclones. The heat potential near the center and east of the cyclone was also playing a role in promoting Jiang-Huai cyclones to develop.