18th Conference on Weather and Forecasting, 14th Conference on Numerical Weather Prediction, and Ninth Conference on Mesoscale Processes

Monday, 30 July 2001: 9:30 AM
The next version of the Canadian operational GEM regional mesoscale model
Jocelyn Mailhot, MSC, Dorval, PQ, Canada; and S. Bélair, A. Tremblay, A. Méthot, B. Bilodeau, L. -. P. Crevier, and A. Glazer
A new mesoscale version of the GEM regional model in operation in Canada for numerical weather prediction has been under development for some time. The main changes to the modeling system include an increased resolution both in the horizontal (on the order of 15 km instead of 24 km) and the vertical (45-50 levels instead of 28) and improvements to the physics package. These include a new surface processes package (with a mosaic-type treatment of land surface over continents - ISBA scheme with vegetation and snow -, open waters, sea ice, and glaciers), an improved formulation of the boundary layer to represent clouds with a unified moist turbulence approach, Kain- Fritsch deep convection scheme, and the Tremblay mixed-phase condensation scheme with explicit microphysics, together with revisions to the cloud radiative optical properties. The new surface package uses a high-resolution dataset to generate the geophysical fields (vegetation types, soil properties, ,...) and a sequential assimilation method has been developed for surface and soil variables (soil temperature and soil moisture). An overview of the various aspects of the new mesoscale modeling system will be presented at the Conference. A few case studies will be shown to illustrate some interesting mesoscale features.

Supplementary URL: