Extended Abstract (164K)4.5
Diagnostics of deep convection using radar data and mesoscale numerical model
Gregor Gregoric, University of Ljubljana, Ljubljana, Slovenia
The problem of parameterization of deep convection in limited area mesoscale numerical models (LAMs) is well known and discussed. Roughly we can divide the problem into two categories: the scale and the closures. The horizontal scale of even single convective cloud is close to the LAM's mesh distance; therefore deep convection cannot be considered as "sub-grid" process. Specially in the case of non-hydrostatic models which can resolve convective clouds there is always danger of "double counting". Since deep convection does not cover only a small part of grid elements it is difficult to find the "control process" of convective activity (such as low-level moisture convergence in large scale) which could provide necessary closures.
The closure problem (and partially the scale problem) could be eliminated to some degree if one would know the characteristics of convective clouds such as the size, position and cloud tops height. This information could be provided by weather radar. Therefore combination of mesoscale parameterization scheme of deep convection (for example the Kain-Fritsch scheme) and information derived from radar could yield new information about convective activity. The position and size of convective mass fluxes could be estimated from cell size instead of iterative instability removal which is implemented in the scheme. An attempt of such a combination will be presented.
Session 4, Assimilation of Radar Data in Atmospheric Models—COST 717 & Others
Friday, 20 July 2001, 9:00 AM-12:30 PM
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