Aspects of the parametrization of organized convection: contrasting cloud resolving model and single column realizations

D. Gregory1 and F. Guichard1,2

1European Centre for Medium-Range Weather Forecasts, Reading, United Kingdom
2Centre National de Recherches Météorologiques/GAME (CNRS & Météo-France), Toulouse, France

Quarterly Journal of the Royal Meteorological Society, 2001, vol 128, 625-646.

Summary: Cloud resolving model simulations of organised tropical convection in TOGA-COARE are used  to evaluate versions of the ECMWF convection and cloud schemes in single column  model simulations. Emphasis is placed upon the ability of the convection scheme to represent  "cloud scale" processes, with a typically mode 1 heating structure through the troposphere, with  the cloud scheme representing the stratiform (mesoscale) component with upper level heating  and low level cooling due to the evaporation of precipitation. While diagnosis of convective and stratiform precipitation is sensitive to the sampling criteria applied to the CRM, vertical structures of the mass and heat budgets are robust. Using  diagnostics from the cloud  resolving model simulations as a guide, revisions to the convection and cloud schemes are suggested in order to enable the parametrization to represent the two scales. The study suggests that a mass flux convection scheme linked via detrainment to a prognostic treatment of cloud can  represent organised convection provided the upward motion in the upper level stratiform cloud is  considered.