Chen, Ching-Hsuan, author2022-03-282022-03-281995-11https://hdl.handle.net/10217/234584November 1995.We have adopted Johnson's approach to construct an updraft-downdraft ensemble model as an extension of the prognostic Arakawa-Schubert cumulus parameterization. The downdraft parameterization is used to determine the effects of downdrafts on temperature, moisture, and momentum. It has been tested in extended simulations with the Colorado State University General Circulation Model. Comparisons between simulations with the updraft-only parameterization and with the updraft-downdraft parameterization reveal several improvements. These include: (1) a more realistic global precipitation pattern and cloud distribution; (2) a cooler and more humid tropical troposphere; and (3) a relatively well-defined easterly jet in the upper troposphere of the Indian summer monsoon region. Downdrafts tend to moisten and cool the lower cloud layer, thus enhancing the convective instability of the cumulus environment and generating more lower tropospheric clouds. They also dry the boundary layer, by injecting dry air. In strongly convective regions, convective downdrafts increase the surface sensible and latent heat fluxes.reportsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Convection (Meteorology)Atmospheric circulationText