青藏高原地面与卫星云雷达观测云量的比较

Comparison of cloud cover of the Qinghai-Tibet Plateau obtained from ground station and CloudSat observations

利用2007年1月至2008年12月的CloudSat 2B-GEOPROF-LIDAR品和9210业务网下传的地面观测资料,对比分析了两种方式得到的青藏高原及周边地区年平均总云量及低云量的分布特征。主要结果有:总云量的极值区具有一致性,两种方式得到的高值区均位于高原主体东南侧,低值区均位于印度半岛北部;总云量在量值上存在明显差异,前者几乎在所有区域都高于后者,平均偏差午间为17.8%,凌晨为25.7%;低云量在分布形态上具有较好的一致性,两者的高值区位于云贵高原,而低值区均位于印度半岛北部及高原北部戈壁沙漠;低云量在量值上依然存在差异,两者的平均差值午间为15.3%、凌晨为14.2%。此外,探讨了两种观测得到的云量差值与地面站点密度之间的关系,结果显示,站点密集区的地面观测格点化结果与CloudSat观测结果具有更好的一致性。

The CloudSat 2B-GEOPROF-LIDAR products and ground observations from the 9210 operational networks from January 2007 to December 2008 are compared and analyzed to obtain the distribution characteristics of annual mean total cloud cover and low cloud cover of the Qinghai-Tibet Plateau and surrounding areas.The main results are as follows:①the extremum area of total cloud cover are consistent;the high-value areas obtained by the two methods are all located on the southeast side of the main plateau,and the low-value areas are located in the northern part of the Indian Peninsula;②there is an obvious differ ence in the total cloud cover;the former is higher than the latter in almost all areas,with an average deviation of 17.8%in the noon and 25.7%in the wee hours;③the low cloud cover of the two observations has a good consistency in distribution form;the high-value areas are in the Yunnan-Guizhou Plateau and the low-value areas are in the northern part of the India peninsula and the Gobi Desert in the north of the Plateau;④the average difference of the low cloud cover between the ground and CloudSat observa tions is 15.3%in the noon and 14.2%in the wee hours.Finally,the relationship between the cloud cover differences derived from the two kinds of data and the density of ground stations is discussed,and the results show that the gridded observation results from areas with densely distributed stations have better consistency compared with those of CloudSat.