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气象:2012,38(2):182-187
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上海地区近10年冷流降雪天气诊断分析
(上海中心气象台,上海 200030)
Diagnosis Analysis of Cold Airflow Snowfall Events over Shanghai Area in Recent 10 Years
(Shanghai Meteorological Center, Shanghai 200030)
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投稿时间:2011-02-14    修订日期:2011-09-29
中文摘要: 统计了近10年发生在上海地区的冷流降雪过程,初步揭示了此类天气过程的产生机理,并分析了降雪发生时对应的高低空天气形势、探空图、卫星云图和雷达回波特征。结果表明:上海地区2000—2009年共出现冷流降雪12次,占降雪总日数的25%,大部分过程降雪明显时段高空500 hPa上海处在槽前。冷流降雪发生前,宝山站探空图上,低层有不稳定层结,且850~925 hPa湿度较大。冷流降雪对应的红外云图,云阶走向和海岸线一致,且云体呈白亮波状结构,云顶高度多在3000 m以下,雷达反射率因子较弱,多低于35 dBz。绝
Abstract:Using upper and lower weather chart data, sounding data, radar and satellite data, the cold airflow snowfall events which happened in recent 10 years in Shanghai area were studied and the mechanism for this kind of weather was preliminarily revealed. The conclusions are as follows: there are total 12 cold airflow snowfall events over the year 2000 to 2009 in Shanghai area, which take up a proportion of 25% of the whole snowfall weather days for recent 10 years in Shanghai area. Most of the events, when the snowfall is notable, happened to have a trough behind Shanghai area on the 500 hPa weather chart. Before the cold airflow snowfall, the stratification in the low layer of the sounding data at Baoshan Station was often unstable, and it was usually very moist between 850 and 925 hPa levels. On the satellite image of cold airflow snowfall, the cloud which has a shape of white bright wavy structure and a height below 3000 m, goes in the same way as the trend of coastline. Radar reflectivity was very weak, usually less than 35 dBz for most of the cold airflow snowfall events, and the difference in temperature between sea surface and 850 hPa level was 10 to 14℃, while on the 925 hPa level the difference was 8 to 11℃. The wind direction of Baoshan Station was NW WNW N and wind speed was 3—6 m·s-1 during cold airflow snowfall. Compared with Shandong Peninsula, the cold airflow snowfall in Shanghai area has a smaller range, shorter duration and lower intensity because of its special geographical position and topographic condition.
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基金项目:国家自然科学基金面上项目(41175050)资助
引用文本:
陈 雷,戴建华,韩雅萍,2012.上海地区近10年冷流降雪天气诊断分析[J].气象,38(2):182-187.
Chen Lei,Dai Jianhua,Han Yaping,2012.Diagnosis Analysis of Cold Airflow Snowfall Events over Shanghai Area in Recent 10 Years[J].Meteor Mon,38(2):182-187.