Horizontal and vertical scales of convective clouds over China and the surrounding oceans

Using the level 2 CloudSat-CALIPSO product 2B-CLDCLASS-LIDAR from January 2007 to December 2010, the occurrence frequencies of convective clouds over China and its surrounding oceans are calculated. Based on the frequencies, China and the surrounding oceans are first divided into four regions, i.e. the Tibetan Plateau region (TP), the eastern land region (EC), the southern ocean region (SO), and the Northwest Pacific region (WP). Horizontal and vertical scales of convective clouds over these four regions are then studied. Results show that the horizontal scales of cumulus clouds over the ocean and land are about 2 and 1 km respectively,indicating a more scattered feature over land than over the ocean.Cumulus clouds over the ocean show a larger scale because of the homogeneous thermodynamic property of ocean. Horizontal scales of deep convective clouds show a feature opposite to the cumulus clouds, the scale range is 10-50 km with the largest scale of approximately 45 km in EC, and the smallest scale of about 30 km in WP. The horizontal scale of deep convective clouds over land is larger than that over the ocean and displays a multi-scale feature, which is attributed to the complicated weather background over the ocean. The vertical scale of cumulus clouds is within the range of 0.24-2 km without obvious differences among the four sub-regions. The vertical scale of deep convective clouds over the ocean are deeper than that over the continent, with the maximum (15 km) in SO and the minimum (10 km) in the TP. Deep convective systems show a smaller and deeper range over the ocean than over land.