2016年秋末宁夏一次雨雪天气过程降水相态特征分析
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摘要
利用ECMWF 0.125°×0.125°再分析资料、常规观测资料等,分析了2016年10月26—27日宁夏一次雨雪天气过程降水相态转换的天气成因,分析总结此次雨雪相态转换的预报指标。结果表明:在气温异常偏高的气候背景下,较强冷空气东移南下导致大气温度持续下降,0℃层高度也随之下降,降水性质由降雨向降雪转换。降雪发生时,地面气温在2℃以下,雨夹雪地面温度在-1～2℃,受地形和下垫面性质影响,宁夏川区降水相态过渡带的地面温度高于南部山区;川区0℃层高度下降到850 hPa以下,南部山区0℃层高度下降到775 hPa以下,即川区850 hPa温度≤0℃、700 hPa温度≤-4℃,山区850 hPa温度≤2℃、700 hPa温度≤-2℃,将从雨逐渐向雨夹雪或雪转变;降雪发生前,银川站和青铜峡站在825hPa到775hPa有逆温存在,降雪发生后,两个测站探空曲线均发生变化,逆温层消失。
Based on ECMWF 0.125°×0.125° reanalysis data and conventional observation data, the weather genesis of precipitation phase transition during a rain and snow weather in Ningxia from October 26 to 27, 2016 is analyzed. The forecast indexes of the phase transition of rain and snow are analyzed and summarized. The results show that under the climatic background with abnormally high temperature, the strong cold air moves eastward and southward, causing the decrease of atmospheric temperature and the 0 ℃ layer height. Consequently, the precipitation changes from rainfall to snowfall. When snowfall occurs, the surface temperature is below 2 ℃, and the sleet is in the range of-1 to 2 ℃. Due to the influence of topography and underlying surface properties, the surface temperature of the precipitation transition zone in Ningxia Chuan area is higher than that in the southern mountainous area. The height of the 0 ℃ layer descends to below 850 hPa in Chuan area, and it is below 775 hPa in the southern mountainous area. This means that at the height of 850 hPa and700 hPa, the temperature is not over 0 ℃ and 4 ℃, respectively, in Chuan area but the temperature is below 2 ℃ and-2 ℃ in the mountainous area. The precipitation gradually changes from rain to sleet or snow. Before the snowfall occurrence, Yinchuan Station and Qingtongxia Station have an inversion temperature from 825 hPa to 775 hPa. After the snowfall, the sounding curves of the two stations changes and the inversion layer disappears.
Based on ECMWF 0.125°×0.125° reanalysis data and conventional observation data, the weather genesis of precipitation phase transition during a rain and snow weather in Ningxia from October 26 to 27, 2016 is analyzed. The forecast indexes of the phase transition of rain and snow are analyzed and summarized. The results show that under the climatic background with abnormally high temperature, the strong cold air moves eastward and southward, causing the decrease of atmospheric temperature and the 0 ℃ layer height. Consequently, the precipitation changes from rainfall to snowfall. When snowfall occurs, the surface temperature is below 2 ℃, and the sleet is in the range of-1 to 2 ℃. Due to the influence of topography and underlying surface properties, the surface temperature of the precipitation transition zone in Ningxia Chuan area is higher than that in the southern mountainous area. The height of the 0 ℃ layer descends to below 850 hPa in Chuan area, and it is below 775 hPa in the southern mountainous area. This means that at the height of 850 hPa and700 hPa, the temperature is not over 0 ℃ and 4 ℃, respectively, in Chuan area but the temperature is below 2 ℃ and-2 ℃ in the mountainous area. The precipitation gradually changes from rain to sleet or snow. Before the snowfall occurrence, Yinchuan Station and Qingtongxia Station have an inversion temperature from 825 hPa to 775 hPa. After the snowfall, the sounding curves of the two stations changes and the inversion layer disappears.
引文
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