Research On Climate Characteristics And Physical Factors Of Rainstorms At The Rear Of Typhoons In Fujian Province

In this paper, based on the past year typhoons data by China Meteorological Press, the typhoons between 1961 and 2006 is investigated in the field from 20°N to 28°N and from 114°E to 125°E. By analyzing the precipitation data, we found the rainstorms at the rear of typhoon in Fujian province and then summarized. the climate characteristics. The rainstorms at the rear of typhoon in Fujian province are often happened at the Daiyu Mountain which is in middle-south in Fujian province and some special landform in the east of Bopingling Mountain. Southeast in the Fujian province is the most occurring district that its wind from south and southwest in upper layer brought the cloud from seas to southeast of Fujian.Following, using bilinear interpolation we can transform from NCEP 1°×1°data to 0.6°×0.6°final analysis data, we calculated the circumstance and physical factor of typhoons by the MM5 mode. We classified the typhoons between 1961 and 2006 which are rainstorm and non-rainstorm at the rear of typhoon in Fujian province. Then we separated and compared with these factors of the two sorts in the circumstance and physical factors and concluded some results. In the cases, a closed low-pressure cyclone exists in the north of South China. The height of the low pressure center and the height in the Fujian province in the cases of rainstorms are lower than those of non-rainstorms. The jet partial to the south at the low-lever exists from the coast of Fujian to Taiwan Strait. Those low-lever jets make water vapor, thermal transport and convergence ascending motion strongly. The rainstorms at the rear of typhoon needs some exponents such as: (k), specific humidity (q), water vapor flux (qf), the difference between the temperature to dew-point temperature (t-td), the pseudo-equivalent potential temperature, the vortex (vor), and the vertical speed whose value are bigger than some standard.Finally, we analyzed the durative rainstorms which the rear cloud effected the area of Fujian province after 0604 severe tropical storm "Billis" landing at the Fujian province. Continental high-pressure and western Pacific high-pressure were very strong and steady. Severe tropical storm of 0604 "Billis" localized in the north of South China by the baring of continental high pressure. The middle-south of Fujian province located the convergence area of the low pressure cyclone at the outer. During the period the water vapor came from two currents. One is southwest airstream, which comes from cross-equatorial flow and the Bay of Bengal flow, anther is southeast airstream, which comes from the southern side of western Pacific high pressure. The strength of southwest jet is stronger in the effected period than the average of its histories at the same time evidently.In conclusion, this article firstly defined the rainstorms at the rear of typhoons in Fujian province and analyzed the climate characteristics, the circumstance, the dynamical and thermal factors characteristics in detail. Those can help meteorologists and forecasters know about the occurring and developing ruler of rainstorms at the rear of typhoons in Fujian province in all sides. At the same time, by the MM5 mode we calculated all the rainstorms at the rear of typhoon in Fujian province between 1961 and 2006. Firstly through fifteen years numerical products of high differentiation quotiety, we analyzed the physical factors diagnoses rainstorms at the rear of typhoons in Fujian province and found a few new ideas.