HR: 1340h
AN: A53A-0854    [Abstracts]
TI: A strong boundary layer mixing process used in the Canadian Regional Climate Model
AU: * Jiao, Y
EM: jiao.yanjun@uqam.ca
AF: University of Quebec at Montreal, 550 sherbrooke west, 19th floor, west tower, Montreal, QC H4N 1P2 Canada
AU: Caya, D
EM: caya.daniel@ouranos.ca
AF: OURANOS, 550 sherbrooke west, 19th floor, west tower, Montreal, QC H4N 1P2 Canada
AU: Laprise, R
EM: laprise.rene@uqam.ca
AF: University of Quebec at Montreal, 550 sherbrooke west, 19th floor, west tower, Montreal, QC H4N 1P2 Canada
AB: In this study, a strong boundary layer mixing process from the Canadian Atmospheric General Circulation Model (AGCM) is implemented into the third generation of Canadian Regional Climate Model (CRCM) as an effort to improve the simulation of vertical distribution of temperature and water vapor in the boundary layer, further to improve the model performance in simulating summer land precipitation. In stead of exchanging latent and sensible heat fluxes only with lowest boundary layer, the new strong mixing process evenly imposes the increments of water vapor and potential temperature on the whole boundary layers so as to directly mimic the non-local mixing effects during the strong surface heating events. The new mixing scheme (along with some adjustment in the soil water holding capacity field) significantly improves the vertical distributions of water vapor and temperature in the boundary layer; the spatial distribution patterns of total cloudiness are also improved while compare with the observation from the International Satellite Cloud Climatology Project (ISCCP). In addition, as a consequence of improvement in the boundary layer simulations, the deep convection is triggered more realistically than before, so the intensity of convective precipitation is reduced drastically, this results in the simulation of the total summer precipitation becomes more realistic while compare with the observation.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting