Evaluation of the convective mass flux profiles associated with cumulus parameterization schemes of CMIP5 models

Abstract

While the numerical models are being run with increasing resolutions, the parameterization of cumulus convection used in the general circulation models, irrespective of closure assumption and trigger mechanism, continue to use the mass flux framework. To address one of the most important components of convective parameterization, vertical profile of mass flux is examined. We have compared the convective mass flux of the Coupled Model Intercomparison Project Phase 5 (CMIP5) models during Boreal summer over the Eastern Pacific, Western Pacific and Indian Ocean with that of ERA – Year of Tropical Convection (YOTC) reanalysis dataset. The analyses suggest that most of the models overestimate the mass flux by an order over all the oceanic basins and interestingly the vertical structure also appears similar for all the CMIP5 models irrespective of ocean basins. In view of this, we state that the improper mass flux distribution in the cumulus parameterization schemes of global models need to be improved to reduce some of the uncertainties arising from the cumulus schemes of climate models which in turn impact the precipitation bias of the models.