Tropical Tropopause Layer Cirrus Clouds as Seen by Cloudsat and Calipso

Cirrus clouds in the tropical tropopause layer (TTL) are posited to play an important role in the physics and chemistry of the air that eventually enters the stratosphere and in the Earth's radiation balance; but their location and tenuous nature have made them difficult to observe and, as a result, more poorly understood than other types of cloud. The advent of the A-Train sensors, however, now affords unprecedented views of these clouds and the opportunity to shed new light on their possible formation mechanisms and on their various possible radiative impacts. Toward this end, radar and lidar data taken from aboard the CloudSat and Calipso satellites are here used to demonstrate statistics of the seasonal and spatial variability of TTL cirrus clouds along with their tendency to occur with other, lower clouds.