Progress toward the assimilation of surface sensitive infrared channels over land at Environment Canada

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Tuesday, 6 January 2015: 4:00 PM
230 (Phoenix Convention Center - West and North Buildings)
Louis Garand, EC, Dorval, QC, Canada; and S. K. Dutta

Currently, infrared radiances which are sensitive to the surface are only assimilated over ice free oceans at Environment Canada (EC), as is the case for most weather centers. Work toward the assimilation of such data over land surfaces has recently progressed significantly. Assimilations cycles were conducted for two-month periods using the new EC's global ensemble-variational analysis system. That system uses a flow-dependent background error covariance matrix which includes terms relating surface skin temperature and atmospheric variables. About 140 AIRS and IASI channels are assimilated. Among these, about 40 are sensitive to the lower troposphere and surface. The experiment consists in allowing the assimilation of surface sensitive AIRS and IASI channels over land and sea ice under certain restrictive conditions, essentially clear sky, relatively flat topography, and high surface emissivity (exclusion of bare surfaces). This still leaves substantial areas accepting the additional data. First results showed a negative impact in polar areas, possibly due to cloud contamination. However, overall positive impacts were obtained when excluding latitudes above 60o. Under current quality control conditions, the volume of assimilated surface-sensitive channels increases by about 15 %. Details of the approach will be presented along with most recent results.