Satellite radiance assimilation impact in new canadian ensemble-variational system

The impact of satellite radiances is reassessed in the context of the upcoming ensemblevariational data assimilation system at Environment Canada, which benefits from a flowdependent background error covariance matrix. Data denial experiments, consisting of removing either microwave or infrared radiances, confirm the large positive impact from both observation types. The impact in forecasts is further increased by doubling the number of assimilated hyperspectal IR channels (142 each for AIRS and IASI), and optimizing the assigned observation error and bias correction procedure. Impact evaluation is also evaluated from degrees of freedom (DFS) statistics pertaining to various observation types and individual channels.