Cloud venting - A review and some new global annual estimates

In this paper we review observational and modeling studies of cloud venting by a wide variety of cloud types ranging from ordinary cumuli, to ordinary cumulonimbi, mesoscale convective systems and tropical and extratropical cyclones. We have used explicit cloud-resolving simulations with RAMS to illustrate the nature of the process of venting of boundary layer air by several cloud system types and to provide quantitative estimates of the transport rates for different storms. In order to help global modelers prioritize their efforts in developing and refining cloud transport parameterization schemes, we have also attempted to make global estimates of the contributions of the various storm types to venting of boundary layer air. We find that on a global-annual basis, the extratropical cyclone has the highest boundary layer mass flux of all cloud venting systems, followed by the general class of MCS's (excluding MCC's), ordinary thunderstorms, tropical cyclones, and MCC's. We estimate an annual flux of 4.95 x 10(19) kg of boundary layer air by these cloud systems, which represents a venting of the entire boundary layer about 90 times a year.