不同初始场对一次西北地区暴雨影响的数值模拟研究

利用WRF3.8.1模式研究了 GRAPES_GFS、FNL和ERA-interim三种资料形成的不同初始场对2017年8月6-7日西北地区一次暴雨过程模拟结果的影响.此次暴雨是由于南亚高压和高空急流的加强,副热带高压西伸北抬,偏东风低空急流和低空切变线的发生发展造成;三种资料中只有GRAPES_GFS资料中可以分析出...

Numerical Studies on Effects by Different Initial Fields on a Rainstorm in Northwest China

Effects of different initial fields from global data such as GRAPESGFS,FNL and ERA-interim on a rainstorm process which occurred in the Northwest of China from 6 to 7 August 2017 were studied with Mesoscale model WRF V3. 8. 1 Synoptic analyses show that the formation and evolution of the rainstorm was caused by the strengthen of the South Asia High associated with the upper jet at 200 hPa,westwards extending and northwards moving of the subtropical high as well as development of the plateau trough at 500 hPa and low-level shear line at 700 hPa. Comparative analyses indicate that only easterly low-level jet at 700 hPa was appeared in the GRAPESGFS data among three kinds of data,which may be the mainly synoptic system for difference of simulated distribution of precipitation with different initial fields. There are some differences at middle and low levels of troposphere in simulated results with three initial fields,which are not obvious at upper levels. A deep trough was appeared in the southeast part of Gansu province in simulated output by initial field from GRAPESGFS data at 500 hPa,which was a closed low system by initial field from FNL data,while no obvious low systems by initial field from ERA-interim data;At level of 700 hPa,development of easterly low-level jet stream and cyclonic circulation systems can be simulated with three initial fields and there are slightly difference in intensity of simulated systems. According to the distribution of precipitation,simulated results have obvious differences by three initial fields,the location of precipitation center and the regional average precipitation rate simulated by initial field from FNL data were the best among three different initial fields,according to evaluation indexes such as TS,FAR and POD,initial filed from GRAPESGFS data was the best but the rate of vacancy forecast of rainfall below 20 mm level was relatively larger;Simulated results with initial field from ERA-interim data were the worst in this case.