西北地区东部冰雹云的卫星光谱特征和遥感监测模型

Satellite Spectrum Character of Hail Cloud and Pattern of Remote Sensing Monitor in East of Northwest China

根据气象台站的冰雹观测记录,针对冰雹灾害多发的西北地区东部,选取2001—2004年间14次NOAA卫星过境的AVHRR资料,共88个样本数,对冰雹云和其他云的光谱特征进行对比分析。结果表明,雹云的热红外亮度温度的变化基本在245K以下,中红外波段反射率相对较低,基本变化在0.4及以下范围,可见光和近红外波段反射率>0.6。冰雹产生的两个重要条件是高的云光学厚度和大的云粒子有效半径共同发生的区域;西北地区冰雹发生的云顶高度基本在4.5～7km之间。根据雹云的光谱特征,确定雹暴指数及其模型阈值>0.35的冰雹监测方法,多普勒雷达回波和气象站观测结果说明,雹暴指数等多参数结合判别冰雹云效果显著。

According to recorder of hail observation of weather station, aiming at hail damege areas in east of Northwest China, AVHRR data of NOAA satellite at 14 passages during 2001～2004 are selected, and a total of 88 samples are used to analyse the spectrum characters of hail cloud and other type clouds, and the model of hail storm index is confirmed and defined. The result show that the change of heat infrared bright temperature of hail cloud is lower than 245K, the reflectance of middle infrared band is lower than 0.4, and the reflectances of visible and near infrared bands are larger than 0.6. Two important conditions produced hail are common ocurring areas of hight cloud optical depth and efficient radius of hight cloud particle. The cloud top hight of hail ocurring in the east of northwest china is 4.5～7 km. The results of Doppler radar echo and observation of meteorological station show that the combination hail strom index and several other parameters are significent in the discriminatton of hail cloud.