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

Monday, 30 July 2001: 4:20 PM
The Canadian 3D-Var Analysis Scheme on model vertical coordinate
Clément Chouinard, MSC, Dorval, PQ, Canada; and C. Charette, J. Hallé, P. Gauthier, J. Morneau, and R. Sarrazin
Poster PDF (283.4 kB)
The operational 3D-Var analysis system of the Canadian Meteorological Centre (CMC) has undergone major revisions in the last two years. First, in June 2000, it was converted from a 16-pressure to a 28-h level system including a complete revision of background and observational errors; secondly, in September 2000, the use of satellite data was updated to directly assimilate TOVS radiances, and these have produced very significant improvements downstream of data void areas such as Western NA and in the SH.; and thirdly, in January 2001, the regional spin-up system was fully upgraded to 28 h levels and the direct assimialtion of TOVS radiances. Results and impacts of these major revisions will be presented.

The mass variable of the current 3D-Var regional and global systems remains the geopotential, consequently, the surface pressure is used indirectly as a proximity to surface geopotential datum. Similarly, temperature is not directly assimilated such that significant level temperatures from RAOBS and aircraft temperature reports are not assimilated. Recently, work has been ongoing to introduce the direct assimilation of temperatures and surface pressure from RAOBS instead of geopotentials. Moreover, temperature and moisture from the synoptic meteorological (SM) network are now directly assimilated producing larger and more consistent corrections to the trial field thereby improving the surface and PBL structures. Results from assimilation cycles will be shown to illustrate the impact of surface and upper air temperature data on analyses and 10-day forecasts.

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