Use of AMSU-B radiances in the Canadian Meteorological Centre 3D-var system
Jacques Hallé, CMC, Dorval, QC, Canada; and C. Chouinard
The Canadian Meteorological Centre (CMC) 3D-var is an incremental analysis system that is currently used by both our global and regional models. During the last few years, it has undergone a series of upgrades from isobaric to a terrain-following coordinate, and most importantly the assimilation allows for direct assimilation of satellite radiances.
In terms of radiance data, the operational system currently uses so-called raw level-1b AMSU-A whose quality and bias are controlled by the data user and not the producer. The quality control (QC) and thinning algorithms of the radiance data are more complex and air-mass dependent, but their impact on analyses and forecasts are very large, most noticeably in the Southern Hemisphere.
The resolution of NWP forecast/analysis systems is forever increasing and so is the volume of data from various instruments. The volume of satellite data has become quite a challenge even at the level of ingest and QC. One aspect of NWP systems which definitely can benefit from this additional data is the moisture analysis. In that context we have started to experiment with the ingest of water sensitive radiances from the AMSU-B instruments onboard NOAA-15 and NOAA-16 (and soon NOAA-17) . As will be shown, the quality of both the temperature and moisture analyses are significantly improved when using these additional satellite data. Improvements in the analyses and forecasts are greatest in the Tropics. Preliminary evaluations of the impact of AMSU-B radiances on quantitative precipitation forecasts (QPF) are encouraging.
Extended Abstract (184K)
Supplementary URL: http://iweb.cmc.ec.gc.ca/cmc/bibliotheque/ASSIMILATION/tovs_processing.pdf
Poster Session 3, Data Assimilation
Tuesday, 11 February 2003, 3:30 PM-5:30 PM
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