【摘要】 利用唐山2006—2013年区域自动站降水资料,分析了夏季降水和短历时强降水的日变化特征。结果指出,与一般性降水相比,短历时强降水更具夜间多发性,夜间降水量占总降水量的66.4%,降水量和降水频次日变化呈单峰结构,峰值出现在凌晨,谷值出现在午后,降水强度呈双峰结构,峰值出现在午后和凌晨,且8 a间夜间短历时强降水呈上升趋势。短历时强降水日变化特征地区差异较大,东北部出现频次最多,西南部频次最少、降水强度最大。唐山东北部呈簸箕状,西北东三面环山,强降水过程多东南风,迎风坡抬升加强上升运动,使其出现频次明显偏多;西南部临海,水汽条件比东北部好,故降水强度最大。东北部午后16时(北京时)的降水次峰值与西南部凌晨04时的峰值成因与海陆风昼夜变化关系密切。更多还原

【Abstract】 The diurnal characteristics of summer precipitation and summer short-duration heavy precipitation were analyzed using rainfall data at regional automatic weather stations from 2006 to 2013 in Tangshan. Results show that the short-duration heavy precipitation had higher nocturnal frequency than overall rainfall in general. The percentage of nocturnal precipitation frequency was 66.4%; the peak value of the accumulated rainfall amount and rainfall frequency occurs at early morning, while the valley value appears in the afternoon. The diurnal variation in the rainfall intensity had two peak value intervals. One peak value was in the afternoon and the other peak value happened in early morning. Nocturnal precipitation showed an increasing tendency from 2006 to 2013. The short-duration heavy precipitation diurnal variations showed clear regional differences. The northeast had the maximum precipitation frequency, while the southwest had the minimum frequency,but with the strongest rainfall intensity. The northeast of Tangshan has higher precipitation frequency because it was ringed on three sides by mountains in the west, east and north, so that the airflow carried by the southeast wind was often upraised by the windward slope to induce severe convective weather. The southwest of Tangshan had the access to the sea, therefore, plenty moisture to produce strong rainfall intensity.Diurnal changes of land-sea breeze had a great role in the formation of the precipitation peaks at 16(CST)in northeast and 4 in southwest.更多还原