利用MODIS数据对北极夏季卷云特性的研究

利用2011~2014年MODIS云产品数据对北极地区夏季卷云的出现概率、云顶温度、云顶高度、光学厚度、有效粒径大小进行统计分析,并讨论了北极地区夏季卷云有效粒径大小和卷云高度的关系。结果表明,北极地区上空夏季卷云出现概率最高,水云较少。卷云云顶温度主要分布在230~272 K(即-43~-5℃),其云顶高度主要在2~8 km,4.5~6 km出现概率最大。卷云的光学厚度主要在小于10范围内。卷云的有效粒径在5~40 m之间,10~20 m出现概率最大。卷云的有效粒径和高度的关系与中纬度地区相反,北极地区卷云高度越高,卷云有效粒径越大。北极地区卷云随着纬度增大,卷云出现概率增加,卷云云顶温度降低,卷云高度增加,卷云有效粒径增大,卷云光学厚度增大。

Cirrus clouds properties in the Arctic in summer based on MODIS data

The Arctic probability distribution of cloud phase, cirrus clouds top temperature, cirrus clouds top height, cirrus clouds optical thickness and effective radius in summer were presented based on Moderate resolution Imaging Spectrometer(MODIS) cloud product data(MOD06) of 2011-2014 in July, and the relationship between effective radius and cirrus clouds top height was discussed. Results show that in summer the occurrence frequencies of cirrus clouds become higher while the occurrence frequencies of water clouds become lower in the Arctic. Cirrus clouds top temperatures mainly distribute in the 230-272 K(that is -43℃ to -5℃). The cirrus clouds top height distribute from 2 to 8 km, and has a highest occurrence frequency in the range of 4.5-6 km. The cirrus clouds optical thickness is less than 10. The cirrus clouds effective radius distribute from 5-40 m and most probable appear in the range of 10-20 m. The relationship of cirrus clouds effective radius and cirrus clouds top height has a positive correlation in the Arctic, while in mid-latitude this relationship is opposite. The higher the cirrus clouds top height,the greater the cirrus clouds effective radius is. In the Arctic, with the increase of the latitude, the cirrus clouds occurrence frequency, cirrus clouds top height, cirrus clouds effective radius and cirrus clouds optical thickness increase, while the cirrus clouds temperature decreases.