The Cloudy Nature of Tropical Rains

Abstract

AbstractFour years of CloudSat cloud and precipitation observations are combined with CALIPSO lidar, Moderate Resolution Imaging Spectroradiometer (MODIS) radiance, and Global Precipitation Measurement (GPM) precipitation data to document the cloud properties of precipitation confined to latitudes between 30°N and 30°S. The relations between two different cloud top heights (CTHs) and precipitation are examined. The maximum CTH observed in the column is one measure (referred to as the highest CTH, HCTH) and the second is the minimum CTH within the same raining column, interpreted to be the tops of the rain‐bearing clouds in the column (referred to as the raining cloud top height, RCTH). Although a broad relation between rain intensity and CTH is shown to exist, especially for shallower warm clouds, the HCTH of the deepest, raining clouds in the tropics is shown to be a poor indicator of precipitation intensity. The implication of the difference between HCTH and RCTH is that for all but the deepest convection, the height of raining clouds is significantly overestimated from observing systems that cannot see below upper cloud layers. The vertical profile of CTHs is shown to be distinctly bimodal with RCTH profiles having a large maximum associated with shallow precipitating clouds, whereas the HCTH distribution has its maximum in the upper troposphere. The influence of this vertical profile information on radiative and latent heating profiles results in a nonnegligible shift in latent heating from an upper level maximum to a more bimodal profile reflecting the increased contribution of shallow raining clouds.