基于SWAN产品的短时强降水雷达特征及预警分析
Forewarning Analysis and Radar Features for Short-time Heavy Rainfall Based on SWAN System Products
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摘要: 利用SWAN产品和自动站雨量资料,详细对比分析了2010~2012年区域性暴雨中的短时强降水雷达特征,结果表明:(1)短时强降水具有反射率因子大,液态水含量高、回波顶高,强回波厚度大等特征,在每隔6min的SWAN拼图产品中,短时强降水通常满足:3km高度处CAPPI回波≥30dBZ,组合反射率CR中心强度≥40dBZ,VIL>5kg/m2,45dBZ以上的回波中心厚度(H)≥3km,这些参数的变化可以作为短时强降水的预警临近指标。(2)现有SWAN产品中的QPE/QPF产品对未来逐小时的雨量和落区具有一定的预报能力,但QPE产品估测1h累计降水量更接近于实况雨量,在监测到有上述强回波发展时,可通过分析QPE产品和回波特征及预警指标对短时强降水过程进行预报。Abstract: Using SWAN products and precipitation data of automatic meteorological stations to analyze short-time heavy rainfall processes from 2010 to 2012 year,the results showed that there are strong reflection feature,high radar VIL、tall top of radar echo feature and thick depth of strong radar echo(≥45dBZ) during short-time heavy rainfall periods.(1) seeing from every 6min SWAN products,short-time heavy rainfall had some following echo features: CAPPI echo ≥30dBZ(three-dimensional radar echo in SWAN products) at 3km height,center of CR reflectivity ≥40dBZ,radar VIL>5kg/m2,the depth of strong radar echo ≥3km.Variations of these radar factors could be forewarning indexes for short-time rainfall.(2)QPE/QPF products could be beneficial to estimate 1h-accumulate precipitation and position of short-time heavy rainfall in future,but compared to QPF products,QPE products could estimate precipitation and position of short-time heavy rainfall more accurately.Therefore,when monitoring development of strong Radar echo,forecasters can use above SWAN forewarning indexes to forecast short-time rainfall.
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