用多谱阈值法进行GMS-5卫星云图云型分类的研究

Cloud Classification of GMS-5 Satellite Imagery by the use of Multispectral Threshold Technique

介绍了利用 GMS- 5卫星云图资料获得晴空、半透明云或碎云和高、中、低云的方法。基于最优回归统计法得出多谱阈值与等压面温度的统计关系 ,利用 MM5中尺度数值预报模式的预报结果计算出动态变化的多谱阈值 ,使云判别阈值能适应不同的天气。实际资料试验表明 :多谱阈值法是一种可行的云判别和云分类的方法。该方法能较准确地区分云与晴空、判别出高云和低云 ,对半透明云或碎云及中云也有一定的判别能力。该方法基本能应用于实时云分类业务。

This paper presents the method for the generation of clouds based on GMS 5 images.A statistical relation between multispectral threshold and temperature on isobaric surface is obtained in the line of the optimal regressive statistics,and a dynamical changeable multispectral threshold is calculated by the virtue of the forecast of MM5 meso scale NWP model in order that the discriminant threshold of cloud adapts to the changeable weather systems.The experiment shows that the method of multispectral threshold is a feasible technique for cloud differentitation and classification,which can exactly distinguish cloud and clear sky,high and low clouds as well as semitransparent or fractional cloud and middle cloud .This technique can be used in the operational cloud classification.