NASA - National Aeronautics and Space Administration

High vertical resolution CloudSat radar measurements, supplemented with cloud boundaries and aerosol information from the CALIPSO lidar, are used to examine radiative heating features in the atmosphere that have not previously been characterized by passive sensors. The monthly and annual mean radiative heating/cooling structure for a 4 year period between 2006 and 2010 is derived. The mean atmospheric radiative cooling rate from CloudSat/CALIPSO is 0.98 K d-1 (1.34 K d-1 between 150 and 950 hPa) and is largely a reflection of the Earth’s mean water vapor distribution, with sharp vertical gradients introduced by clouds. It is found that there is a minimum in cooling in the tropical lower to middle troposphere, a cooling maximum in the upper-boundary layer of the Southern Hemisphere poleward of -10 latitude, and a minimum in cooling in the lower boundary layer in the middle to high latitudes of both hemispheres. Clouds tops tend to strongly cool the upperboundary layer all year in the midlatitudes to high latitudes of the Southern Hemisphere (where peak seasonal mean winter cooling is 3.4 K d-1), but this cooling is largely absent in the corresponding parts of the Northern Hemisphere during boreal winter, resulting in a hemispheric asymmetry in cloud radiative cooling.