K 指数在黑龙江省晴雨预报中的应用

摘要

Although the relative humidity and wind field in lower atmosphere were very effective to forecast rain or shine weather,there were still some missing or false-alarm forecasts.In order to improve the accuracy rates of rain or shine weather forecast in Heilongjiang province,the forming reasons of weather cases with and without rain were analyzed.The results indicate that the temporal and spatial distributions of K index are indicative to rain or shine weather forecast,and could help to forecast the complex weather condition in which relative humidity in low level is small or wind convergence is poor,which are easy to lead to a missing or false-alarm forecast.Precipitation often appears in the high value center area or high energy tongue area of K index and in the strong K index gradi-ent area or energy front,while it is seldom in the low value center area of K index.The threshold values with or without rain in the high and low values area of K index vary in different seasons.%低层相对湿度和风场等物理量场对降水有较高的预报能力，但仍存在空报和漏报现象，为了提高黑龙江省晴雨天气预报准确率，对黑龙江省大量有降水和无降水天气成因进行对比分析。结果表明：K 指数时空分布特点对晴雨预报有十分显著的指示意义，尤其对分析低层相对湿度小或风场辐合条件差等容易出现降水空报或漏报等疑难降水成因，有较好的辅助作用。在 K 指数高值中心区或高能舌区容易出现降水；K 指数梯度较大区或较强能量锋也会触发降水；在 K 指数低值中心区发生降水的可能性较小。不同季节有无降水的 K 指数高值区和低值区的阈值不同。