摘要
2010年8月21日,北京地区出现了一次明显的降水天气,过程总雨量达到大～暴雨。此次降水天气是在副高东退的过程中,西来槽、低层切变和地面倒槽共同影响所造成的。利用NCEP 1°×1°格点资料以及雷达、风廓线、自动站等探测资料,对此次降水过程的成因和发生发展做了分析,并结合当时的预报思路,对造成强降水时段预报存在偏差的原因进行了探讨。结果表明,北京地区此次大～暴雨过程是在副高边缘、高空槽前有利的环流背景下,低层切变线和低空急流共同作用产生的;此次天气过程以暖区降水为主,西南暖湿气流输送和低层偏东风是主要的水汽来源,深厚的湿层为大～暴雨天气过程的发生和维持提供了充足的水汽;东北方向的冷空气从低层渗透下来,将暖空气抬升,是强降水的主要触发条件。对于西来槽加副高天气形势造成的降水过程,在预报中要特别关注低层暖切变(西南风和东南风的切变)的发展,以便分析其所造成的强降水过程中量和时段的变化;实况天气形势的把握和常规探测资料、加密观测资料的分析应用,对于把握降水的量级和强度,判断短时天气的变化,做好预报服务具有重要意义;数值预报的释用还存在不足,如何取舍有待进一步研究。需要加强对数值预报天气形势的分析,利用天气形势来订正物理量场与降水场,以提高预报的准确率。
Beijing appeared an obvious precipitation on August 21,2010. This precipitation was generated by the combined effect of westerly trough, lower shear and surface inverted trough in the process of the eastward retreating of subtropical high. Using detection data of NCEP 1°× 1° grid data, radar, wind profilers and automatic weather stations, causes and the development of this precipitation were analyzed. Combining with forecasting thought then, reasons of forecast deviation during precipitation stage were discussed. The results showed that the precipitation was generated by the combined effect of low-level shear and the low-level jet under the favorable circulation background of the edge of the subtropical high and in the front of upper trough ; The precipitation was mainly in warm sector, and southwest warm-moist air flow conveying and easterly wind of low layers were main sources of moisture. The deep moisture layer offered adequate moisture for the occurrence and maintain of precipitation process. Major trigger condition of precipitation was that northeast-ward cold air permeated from lower layers and lifted warm air. For precipitation process generated by westerly trough and subtropical high, the development of lower warm shear （ the wind shear of south-west wind and south-east wind） should be concerned specially in the forecast to analyze the changes of quantity and time interval during the precipitation process. Holding of synoptic pattern and analysis of various conventional and intimate sounding data were important for grasping the magnitude and intensity of rainfall, judging changes of short-term weather and supplying effective forecasting and service. However, the interpretation of numerical prediction was still inadequate. How to choose needed further research. Analysis of circulation pattern based on numerical weather prediction should be strengthened to revise the physical field and precipitation field to improve forecasting accuracy.
出处
《安徽农业科学》
CAS
北大核心
2011年第36期22411-22414,22537,共5页
Journal of Anhui Agricultural Sciences
基金
中国气象局预报员专项(CMAYBY2011-001)
关键词
暖切变
数值预报
低空急流
西来槽
Warm shear
Numerical prediction
Low-level jet
Westerly trough
