西北典型地域条件下云量的对比分析

Comparison of Cloud Coverage over Northwestern China with Respect to Typical Regions

采用NASA地球观测系统（EOS）“云与地球辐射能量系统（CERES）”2002年7月至2004年6月CERES SSF Aqua MODIS Edition 1B云资料，选取我国西北地区不同气候环境条件下的4个典型地域，研究了总云量、低层云和高层云云量的空间分布特征以及季节和年变化特征。结果表明，低层云量的高值区不仅分布在山脉地区，而且也分布在非山脉地区。但高层云的云量高值区只分布在山脉地区；总体来说，云量大小随地域的不同相差相当大，高层云云量年平均值的最大差异发生在祁连山区和塔克拉玛干沙漠之间，两者相差16．4％。而总云量和低层云量年平均值在季风区和塔克拉玛干沙漠地区相差最大，分别可达27．6％和19．5％。季风区和祁连山区云量最大值一般都出现在夏季，天山和塔克拉玛干沙漠地区云量最大值一般都出现在春季，最小值则均出现在秋冬季。总的来说，3个云量参数值在3～9月较高，最低值出现在10-12月。

Using CERES SSF Aqua MODIS Edition 1B data from July 2002 to June 2004 from Clouds and the Earth＇s Radiant Energy System （CERES） of NASA＇s EOS, the authors analyzed the spatial distribution, seasonal and annual variability of the coverage of total cloud, lower layer cloud and upper layer cloud over northwestern China with respect to four typical regions with different climatic and environmental conditions. The results show that the high measurements of lower layer cloud coverage not only occurred over mountains but also over non-mountainous regions, but the high measurements of upper layer cloud coverage only occurred over mountains. Generally, the cloud coverage measurements varied significantly over the four regions. The largest difference of yearly means of upper layer cloud coverage was between the Qilian Mountains and the Taklimakan Desert which was 16.4%, and those of total cloud coverage and lower layer cloud coverage were both between the Asia monsoon influence region and the Taklimakan Desert which were 27.6% and 19.5%, respectively. The highest measurements of cloud coverage parameters over the monsoon influence region and Qilian Mountains generally occurred in summer while theose over the Tianshan Mountains and the Taklimakan Desert occurred in spring. The measurements of the three cloud coverage parameters were relatively high from March to September and their lowest measurements occurred from October to December.