The Development of an Improved Convective Initiation Scheme for Mesoscale Numerical Weather Prediction Models. Phase 1

Download or read book The Development of an Improved Convective Initiation Scheme for Mesoscale Numerical Weather Prediction Models. Phase 1 written by and published by . This book was released on 1991 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-dimensional nonhydrostatic cloud model, the Terminal Area Simulation System (TASS), is used to investigate the convective initiation process for an idealized case over central Florida where the forcing is provided by differential surface heating. The surface heating pattern is generated from high resolution land use data by making simple assumptions relating surface characteristics to particular land use types. The cloud model simulation produces a complicated field of both shallow and precipitating cumulus clouds. Current mesoscale parameterization schemes are evaluated for their ability to predict convective initiation. Analysis of the results show that in the first half of the run, localized differential surface sensible heating produces small areas of deep convection associated with surface features. In the latter half of the simulation, mesoscale convergence develops due to the lateral boundary conditions and provides a mesoscale organization which is well resolved by a conventional measure of mesoscale moisture convergence. Subgrid scale convergence is very well correlated with convective activity. Results suggest that the cloud model is a valuable tool for the investigation of realistic convective initiation and evolution, and that a combination of mesoscale and subgrid scale properties are necessary for successful mesoscale modeling of cumulus convection.