Deep convective cloud system size and structure: advances toward a new near-global database for linking convective cloud systems to aerosols, thermodynamics and circulation

The distribution of infrared and microwave brightness temperatures within clouds provide both an objective measure of cloud system scale and clues to the internal structure of the cloud system. It is a combination of the thermodynamic structure of the cloudy environment, the mesoscale structure of cloud systems, and the cloud microphysics that conspire to produce cloud systems of a particular horizontal scale. In this manner the variability of convective cloud scale and structure are central to determining the radiative forcing of tropical and summer continental climate by clouds, however the factors influencing these features are poorly understood. Here we explore the relationships among cloud system horizontal scale and structure, environmental convective available potential energy (CAPE), vertical shear of horizontal wind, and aerosol optical thickness (AOT) using collocated multi-spectral satellite and model reanalysis datasets. A strong quantitative relationship is established between the horizontal scale of cloud systems and the CAPE and shear of the environment, however these are not sufficient to predict convective cloud cover because these relationships vary between locations. Systematic differences in cloud system horizontal scale are also apparent for cloud systems associated with high AOT compared to those associated with low AOT, however the magnitude and even the sign of the difference depends on the CAPE and shear of the environment. This work illustrates the insight gleaned from blending multiple data products from satellite sensors together with state-of-the-art model reanalysis. A new near-global database of deep convective cloud systems, currently in development, will be described that spans the modern satellite era. When complete, and composed of millions of observed cloud systems, this database will be suitable for probing the relationships among cloud system size, structure, the atmospheric environment and the general circulation.