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    大连地区短时强降水天气特征及预报指标研究

    Synoptic characteristics and prediction index of short-time strong precipitation in Dalian

    • 摘要: 利用2004-2013年4-10月大连地区7个气象站和249个自动气象站逐小时降水观测数据及常规气象观测数据,对大连地区短时强降水的时空分布特征及气候特征、演变趋势和环流背景进行了分析,并建立了强降水天气预报指标。结果表明:2004-2013年大连地区各气象站短时强降水年平均发生次数为2.2-2.8次,南部和东部地区短时强降水年平均发生次数呈略增多的趋势,中部和西北部地区短时强降水年平均发生次数变化较小,中北部地区短时强降水年平均发生次数呈略下降的趋势。大连地区短时强降水最早出现在4月,最晚出现在10月,7-8月为短时强降水集中出现的月份,强降水多出现在02-10时。短时强降水发生次数具有明显的区域分布特征,由东部向中部和西部呈递减的趋势,大连东北部地区短时强降水发生次数最多,南部地区次之,西北部瓦房店地区短时强降水发生次数最少;其中7月北部地区短时强降水发生次数最多,8月东部地区短时强降水发生次数最多,其他月份短时强降水发生次数较少,说明大连地区短时强降水发生分散性较强。925 hPa与850 hPa平均比湿、700 hPa温度露点差、850 hPa与500 hPa温度差平均值、K指数平均值、0℃层平均高度及暖云层平均厚度等参数阈值可用于短时强降水实际预报业务中,可为大连地区强降水预报提供参考。

       

      Abstract: Using hourly precipitation and conventional meteorological observation data from seven major stations and 249 automatic weather stations from 2004 to 2013,the spatial-temporal distribution and climate characteristics,evolution trend and circulation background of short-time strong precipitation in Dalian were analyzed.The weather prediction indexes of strong precipitation were established as well.The results indicate that regional short-time strong precipitation events occur normally 2.2-2.3 times per year.This number tends to increase slightly in the southern and eastern parts,remains stable in the central and northwestern parts,while decreases slightly in the north-central parts.It usually occurs during April to October,especially during July to August,generally happening from 02:00 to 10:00.The number of times that short-time strong precipitation occurs shows a clear spatial distribution feature,i.e.,increasing from the eastern to the western and central parts.The highest number occurs in the east-northern part,following by the southern part,and the lowest is in Wafangdian of the west-northern part.In July,the highest number of short-time strong precipitation appears in the northern part,and in August,it is in the eastern part.In other months,it shows strong spatial dispersion characteristics.The thresholds,including mean specific humidity between 925 hPa and 850 hPa,depression of dew-point temperature at 700 hPa,average difference in temperature between 500 hPa and 850 hPa,mean K index,mean height of 0℃ layer,and average thickness of warm clouds,can be used to forecast the short-time strong precipitation in real operation.This paper provides a reference for forecasting the strong precipitation in Dalian.

       

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