镇江市寒潮特征分析及中、短期预报模型

Characteristic Analyzing of Cold Waves and Medium-Short Term Forecasting Model in Zhenjiang City

对镇江地区1980-2010年寒潮天气过程及相关物理量统计分析结果表明:寒潮强度与范围成正比,强寒潮和特强寒潮只发生在镇江市4个基本观测站均达到寒潮标准的情况下。寒潮酝酿阶段500 h Pa超长波以波1、波2为主要波型,暴发阶段波3为主要波型。冷空气影响镇江前,500 h Pa纬向平均有效位能有2次能量积聚过程,纬向平均动能在25-45°N内加强,西风指数在35-55°N内出现≥30 m·s^(-1)的峰值。寒潮强度越强,冷空气影响前1~3天500 h Pa寒潮关键区温度和位势高度越低。冷空气影响前后,镇江站最低气温、最低地温、平均气压和850h Pa温度的降(增)幅均随时效增长而增大。利用超长波、纬向平均有效位能、纬向平均动能及西风指数的中期变化结果,通过权重法建立寒潮中期预报模型;利用"CMA最新寒潮等级方法"的判别标准,确定寒潮发生具体日期;根据500 h Pa寒潮关键区温度、位势高度,镇江850 h Pa温度、日最低气温、地表温度的短期变化情况,建立寒潮短期强度等级预报模型。建立的寒潮中、短期预报模型,对2011-2016年镇江出现的15次寒潮过程全部报出,并报准5次强寒潮中的4次寒潮强度等级。

According to the statistics of cold waves and relevant physical quantities in Zhenjiang region from 1980 to 2010, it was found that the intensity of cold waves were proportional to the range of them, a strong or extra strong cold wave only occurred when all the 4 basic observatories in Zhenjiang had reached the standard of cold wave. Wave 1 and wave 2 were the main types of the super long waves at 500 hPa during the gestation period of the cold waves, while wave 3 was the main type during the eruption period. Before the cold air affected Zhenjiang, the zonal average effective potential energy at 500 hPa accumulated twice, the zonal mean kinetic energy was enhanced within 2545°N and the westerly index appeared peak value greater than 30 m·s-1 within 3555°N. The stronger the intensity of the cold waves was, the lower the temperature and potential height of the key area at 500 hPa in 13 days before the cold air effected. Before and after the influence of cold air, the minimum air temperature, minimum ground temperature, mean pressure and the change range of temperature at 850 hPa in Zhenjiang station all increased with the aging. The medium term forecasting model equation were built by the method of weighting with the results of medium term changes of the super long waves, zonal mean effective potential energy, zonal mean kinetic energy and westerly index; the specific date of the cold wave was determined by the criteria of “the latest cold wave grade method of CMA”; the forecasting model of short term intensity grade of the cold waves was established according to the temperature and potential height of the key area at 500 hPa and the short term change of temperature at 850 hPa, daily minimum temperature and land surface temperature in Zhenjiang. The medium short term forecasting model could forecast all the 15 cold wave processes during 20112016 in Zhenjiang, and forecasted the intensity grade correctly 4 times of all 5 strong cold waves.