基于卫星融合降水资料的河北省暖季短时强降水分析

Analysis of Flash Heavy Rain in Warm Season in Hebei Province Based on Satellite Fusion Precipitation Data

利用国家气象中心1998-2018年6-9月0.1°×0.1°分辨率的逐小时卫星融合降水资料,分析河北省暖季短时强降水(1 h降水量≥20 mm)的空间分布、日变化特征及成因,结果表明:短时强降水过程的平均小时降水量、降水频次、降水强度、峰值降水量自东南向西北递减,其中东部沿海降水量最大,太行山和燕山的迎风坡附近存在降水大值中心,此分布特征与地形高度的走向基本一致。河北省短时强降水过程存在明显日变化,短时强降水多发时间与降水量大值出现时间集中分布在15-21时,其中18-19时强降水发生频率高、强度大、范围广。强降水日变化的主要影响因子有两个:一是扰动风场对河北省西北山区和西南平原的惯性震荡动力辐合作用,二是扰动风场对南部水汽输送的增强作用。太行山东部的坡度结构、非地转风垂直切变以及山地-平原螺线管(MPS)环流日变化是太行山东麓强降水集中爆发的主要原因。

Based on the hourly satellite fusion precipitation data with 0.1°×0.1°resolution from June to September during 1998—2018 from National Meteorological Center,the spatial distribution and diurnal variation characteristics and causes of flash heavy rain in Hebei Province were analyzed.The results showed the average hourly precipitation,precipitation frequency,precipitation intensity and the peak intensity of flash heavy precipitation decreased from southeast to northwest,the precipitation in the east coast was the largest,there were high precipitation centers near the windward slopes of Taihang Mountains and Yanshan Mountains,which was consistent with the trend of altitude change.There were obvious diurnal variations in the flash heavy rain process in Hebei Province.The heavy rainfall and large precipitation mostly occurred from 15:00 to 21:00,and it was more obvious in high frequency,high intensity and wide range from 18:00 to 19:00.The diurnal precipitation peak was close collocated with the convergence of perturbation winds in the northwest mountain area and the southwest plain area,as well as the enhancement of the total moisture flux through the south inward boundary by the perturbation winds.The slope structure,the vertical shear of non-geostrophic wind and the diurnal variation of mountain-plains solenoid(MPS)circulation in the eastern Taihang Mountains were associated with the higher occurrence of heavy rainfall near the foot of the mountain.