摘要
2005年7月20—23日，5号台风”海棠”登陆后与中纬度系统相互作用造成了河南省区域性暴雨天气过程。使用NCEP再分析资料，对这次暴雨过程中的螺旋度分布及演变特征进行了诊断分析。结果表明：本次台风倒槽暴雨发生在相对螺旋度大的环境场中，暴雨落在螺旋度大值轴附近偏向大值中心一侧，相对螺旋度值的变化大致反映了暴雨及其影响系统的强弱趋势；本次暴雨发生前和发生时，暴雨区上空对流层低层的局地螺旋度有大值中心形成并维持，而对流层上层则表现为局地螺旋度的低值区；相对螺旋度在反映暴雨强弱和落区方面存在一定局限性，其大小随环境场的风垂直切变大小而变化。
The regional rainstorm process on July 20-23, 2005 in Henan province was caused by the interaction of No. 5 typhoon ＂Haitang＂ landfall with middle-latitude system. Using NCEP reanalysis, the diagnostic analysis is carried through about helicity distribution and development characteristic. Results show that rainstorm influenced by typhoon inverted trough happened in the ambient field with large relative helicity. Rainfall area lies near the large numerical axis and is close to the large numerical center. The change of relative helicity numerical value can roughly reflect the strong or weak trend of rainstorm and its influence system. Before and during the rainstorm occurrence, local helicity which is located in the lower troposphere over the rainstorm area will have large numerical center formation and maintenance ; while local helicity which is located in the upper troposphere will have small numerical value. There is some localization that relative helicity reflects the strong or weak trend of rainstorm and rainfall area, which variation accompanies the vertical wind shear of ambient field.
出处
《气象与环境科学》
2008年第2期25-30,共6页
Meteorological and Environmental Sciences
关键词
台风
区域暴雨
螺旋度
诊断
typhoon
regional rainstorm
helicity
diagnosis
