Analysis of a Rare Continuous Rainy Process in Midsummer

[Objective] The research aimed to analyze a rare low temperature and rainy weather process which happened in Anhui Province from July 22 to August 14,2009.[Method] Based on the data of conventional observation,NCEP analysis field and automatic station,a rare low temperature and rainy weather process which occurred in Anhui Province from July 22 to August 14,2009 was analyzed.The formation reason of continuous rainy process in midsummer was discussed.The circulation characteristics and influence systems of continuous rainy process were revealed.On the base,the influences of configuration of circulation fields and difference of physical quantity fields at high and low layers on range and intensity of precipitation were analyzed.[Result] According to the circulation situation and influence system,the continuous rainy process could be divided into four stages:July 22-24,from July 27 to August 1,August 4-8 and August 9-14.Moreover,it was respectively affected by northeast low vortex,cold and warm air,high-level low trough,typhoon and periphery of subtropical high at four stages.The maintenance of big specific humidity zone provided sufficient water vapor condition for the continuous rainy weather.The rainstorm appeared in dense zone of specific humidity line,where the specific humidity >13 g/kg in the humidity front zone.A temperature trough maintained at 850 hPa.The cold air which continued to diffuse and go south was main reason of the abnormally low temperature during the continuous rainy period.Moreover,it provided ascending motion condition for precipitation maintenance.[Conclusion] The research provided references for actual forecast of continuous rainy weather.

Irregular Information of the Rainstorm in a Continuous Rainy Weather

[Objective] The research aimed to analyze irregular information of the local rainstorm process (during 5-6 September,2009) in autumn continuous rainy weather in north Shaanxi. [Method] Based on V-3θ chart, routine observation data provided by Micaps system, satellite cloud chart and data at 100 automatic meteorological stations of Shaanxi, for rainstorm process in autumn continuous rainy weather in north Shaanxi during 4-10 September, 2009, by using structure analysis method, irregular information in local rainstorm weather was analyzed. [Result] In whole precipitation process, atmospheric structure in rainstorm zone presented obvious evolution process. Before precipitation, typical atmospheric structure information of the sudden convective weather appeared. Obvious ultra-low temperature structure appeared at 200 hPa, and consistent clockwise rotation flow was at vertical wind field. Meanwhile, water vapor was sufficient, and unstable energy existed at low layer. Structure characteristic of the convective strong precipitation appeared by advancing for 12h. As precipitation weakened, unstable energy was released, and ultra-low temperature disappeared. [Conclusion] The research provided some thoughts for the forecast of such weather process.

Analysis of Continuous Rainy and Cold Weather in Yiwu in Early Spring of 2009

Continuous rainy and cold weather in Yiwu in early spring of 2009 was analyzed. The results showed that the continuous rainy and cold weather occurred after temperature increased in early days. It is mainly because that the high geopotential height near Ural Mountains lasted for a long time, while the geopotential height was abnormally low in the east of central Asia. Meanwhile, the Iow-prassure trough in the south of Qinghai -Tibet Plateau was very active and moved towards the east frequently, and subtropical high was strong. Compared with continuous rainy and cold weather in early 2008, during the process of this continuous rainy and cold weather in 2009, the decrease in sea surface temperature of the middle and eastern Pacific Ocean near the equator was weaker; the blocking high pressure was slightly weaker, and the low pressure over Mongolia was strong; subtropical high was stronger and showed zonal distribution; south trough was slightly weaker. Compared with the previous continuous rainy and cold weather, the duration of this continuous rainy and cold weather in 2009 was not the longest, and its sunshine hours were not the least, but its temperature was higher, which might result from obvious increase of temperature in the early days. The research could provide scientific references for the prediction of continuous rainy and cold weather in future.