资源环境科技发展态势分析平台

Characterizing two-layer cloud systems has historically been difficult. These systems have a strong radiative impact on the composition of and the processes in the upper troposphere-lower stratosphere (UTLS). Using 4 years of combined spaceborne lidar and radar observations, the radiative impact of two-layer cloud systems in the tropical UTLS is characterized, and its sensitivity to the properties of top- and bottom-layer clouds is further quantified. Under these overlapping cloud conditions, the bottom-layer clouds can fully suppress the radiative heating caused by high clouds in the UTLS, by inducing strong longwave cooling. If the vertical separation between the layers is <4 km, the radiative heating of the high cloud changes sign from positive to negative. Furthermore, the radiative effect at the top of the atmosphere is investigated, and it is found that the characteristic net warming by cirrus with ice water path <50 g/m(2) is suppressed in the two-layered system.