The Effect of Cloud Type on Earth's Energy Balance

Clouds have long been recognized as one of the largest uncertainties to Earth's changing energy budget. Previous research indicates that improved assessment of cloud impacts on climate requires a better understanding of individual cloud types and their radiative effects. This work documents the effects of nine distinct cloud types on atmospheric radiative balance and heating using 2007-2010 data from CloudSat's multi-sensor radiative fluxes and heating rates product (FLXHR-LIDAR). This dataset leverages high-resolution vertical cloud and aerosol information from CloudSat and CALIPSO to provide the most accurate estimates of vertically-resolved radiative fluxes available to date. The effects of three common cloud classes will be highlighted in detail: cirrus, stratocumulus, and deep convection, to contrast their dramatically different effects on climate. The findings support the qualitative conclusion that cirrus clouds warm the planet and stratocumulus clouds cool the planet, while the longwave and shortwave cloud radiative effect of deep convective cloud cancel each other in the tropics. In addition, cloud types will be regrouped in order to compare the results with classical cloud classifications based on passive sensors including those from the International Satellite Cloud Climatology Project (ISCCP) and Earth Radiation Budget Experiment (ERBE) archives. The new CloudSat/CALIPSO estimate of annual average shortwave forcing is -53 W/m2 in good agreement with previous estimates but CloudSat/CALIPSO observations suggest a 20% lower longwave forcing than other sources. This analysis provides an improved distinction of the radiative effects of low-level clouds, and the cloud boundary information from the active sensors used greatly enhances our ability to accurately discern cloud forcing at the Earth's surface.