基于卫星资料的青藏高原卷云特性研究

Study on Characteristics of Qinghai-Tibetan Plateau Cirrus Based on Satellite Data

青藏高原(下称高原)地区是中国气候的敏感区,为准确认识其上空的卷云特征,利用MODIS的M YD06二级云产品数据,对高原地区卷云的概率分布、云顶高度、粒子有效半径以及光学厚度进行了统计分析。结果表明:(1)卷云在3月和4月出现概率最高,10 12月出现概率最低。在全年中,卷云概率分布为双峰型,1 4月为一个高峰期,7 8月为另一个高峰期;两个低值期出现在5 6月和912月。(2)6月和10月卷云云顶高度的概率分布会产生显著的变化。卷云云顶高度平均最大值出现在7 8月,最小值出现在1 2月。(3)卷云的粒子有效半径主要分布在5~40μm之间,15~25μm间概率最大。卷云粒子尺度平均最大值出现在8 9月,最小值出现在12月至次年2月。(4)卷云的光学厚度主要分布在0~40之间,0~10间概率最大。卷云光学厚度最大值出现在8 9月,最小值出现在12月至次年2月。

The Qinghai-Tibetan Plateau （QTP） is one of the climate sensitive zone in China. The cirrus of QTP was studied for investigating the distribution features based on the MYD06_L2 of MODIS cloud product data. There we analyzed the cloud optical thickness, cloud-top height, effective scale and probability distribution of cirrus. The results showed as follows ： （ 1 ） The cirrus probability of occurrence is higher in March and April and lower in October to December. Nevertheless, it performed a double peak probability distribution pattern. Accord- ing to our research, one peak period is in January to April, and the other is in July to August, the two lower periods occurred in May to June and September to December. （2） The probability distribution of cirrus cloud-top height produced significant change in June and October. The mean height of the cirrus cloud peak appears in the summer months from July to August, and the minimum value appears in the winter months from January to Feb- ruary. （3） The effective radius of the particles in the cirrus cloud is mainly distributed in a range of 5 - 40μm, and the probability is greatest in 15-25 μm. The maximum mean radius of the particles in the cirrus cloud was detected in August to September and the minimum value appeared in December to February. （4） Cirrus optical thickness was ranged in 0-40 with the top probability between 0- 10. There showed a similarity to cirrus effec- tive particles scale, the maximum and minimum of optical thickness was August to September and December to February, respectively.