Environmental modulation of the strength of cloud-radiation-precipitation coupling
Abstract
Cloud-radiation-precipitation feedbacks associated with the variations of convection as surface temperature increases have long been hypothesized mechanisms for regulating climate sensitivity. At the global scale, precipitation is constrained by the net atmospheric radiative cooling, which is determined by the balance between clear sky radiative cooling and the radiative heating of the atmosphere from clouds. Here we focus on the coupling between the atmospheric radiative heating from clouds and precipitation using A-Train observations and test its sensitivity to different environmental regimes. Individual cloud objects, their radiative fluxes, and warm precipitation are identified and characterized using CloudSat/CALIPSO products, with heavy precipitation captured by AMSR-E. Analysis shows that the relative strength of atmospheric radiative heating to precipitation is highly sensitive to thermodynamic regime. As sea surface temperature (SST) and column water vapor (CWV) increase, the ratio of atmospheric radiative heating to precipitation increases due to cloud greenhouse effects that change more rapidly than precipitation. Analysis of the cloud systems show that the increasing strength of radiative heating to precipitation can be attributed to increasing cloud extent, with greater fractions of the cloud comprised of thin anvil. Histograms of cloud extent in different thermodynamic regimes show a shift in the cloud size distributions towards fewer total cloud objects in high SST/CWV regimes; however, they seem to be aggregated into larger systems, which become more efficient at heating the atmosphere per unit precipitation.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A33A..05R
- Keywords:
-
- 3314 Convective processes;
- ATMOSPHERIC PROCESSES