摘要
利用黔西南州8个台站1984-2013年逐日降水资料及美国国家大气中心和环境预报中心(NCEP/NCAR)的第二套再分析逐月资料,分析了近30年黔西南暴雨事件的多时间尺度气候特征,探讨了暴雨异常发生时的大气环流背景。结果表明:黔西南近30年平均暴雨日数东西多中间少;暴雨日数具有下降趋势;2-12月黔西南均会出现暴雨,但主要出现在5-9月,6月暴雨日数达到峰值,有明显的单峰结构特征;MK突变检验及滑动t检验结果表明近30年黔西南暴雨日数不存在突变点。在暴雨偏多年,黔西南地区地面气压上升,有冷空气补充南下,500h Pa等压面略有上升,空气柱厚度略增加,700h Pa平均垂直速度为负值,低层存在上升气流,水汽通量散度为负值,水汽辐合有利于降水产生。在暴雨偏少年,黔西南地区地面气压偏少,500h Pa等压面下降,700h Pa平均垂直速度为正值,低层存在下沉气流,水汽通量散度为正值,水汽辐散不利于降水产生。
Based on the daily precipitation data from 8 stations in southwestern Guizhou and the second re-analysis data from NCEP/NCAR during 1984-2013, the climate characteristics of rainstorm in multi- time scale were analyzed and the atmospheric circulation backgrounds of the abnormal rainstorm were discussed. The results are as follows： Nearly 30 years there were less rainstorm days in the middle southwestern Guizhou than in the east and west; the number of heavy rain days has a downward trend; There were rainstorms during Feb. - Dec. and mainly concentrated during May to Sep with the maximum in June, so the change of rainstorm with the time is to be obvious unimodai structure; M-K mutation test and t test show that there is no mutational point in rainstorm days nearly 30 years. In heavy rain year, with the ground pressure raising, cold air moving to south, 500hPa isobaric rising slightly, air column thickness slightly increased, 700hPa vertical velocity being negative, updraft existing in low-level and the vapor flux divergence being negative, water vapor convergence is advantageous to the precipitation. By contrast, in drought year, with the ground pressure reducing, 500hPa isobaric failing velocity at 700hPa being positive, sinking airflow existing in lower-level and the water vapor flux divergence being positive, water vapor divergence is not benefit for precipitation.
出处
《气象研究与应用》
2015年第2期15-20,I0001,共7页
Journal of Meteorological Research and Application
基金
黔西南州科技局社会发展攻关项目(2014-32)
黔西南州气象局项目(2014-08)共同资助
关键词
暴雨
多时间尺度
天气学成因
黔西南
Rainstorm
muhi-time scale
the weather causes analysis
Southwestern of Guizhou
