4th workshop on assimilating satellite cloud and precipitation observations for NWP

The significant positive impact of assimilating AMSU-A in clear sky at ECMWF has long been challenging to replicate when AMSU-A is instead treated in the all-sky data stream. Through various technical changes in the treatment of all-sky AMSU-A data, it is nearing the point where all-sky AMSU-A can outperform its clear-sky counterpart. In hopes of achieving this, the impacts of changes to data thinning, variational quality control (VarQC), and scene-dependent observation errors are probed in a series of experiments. The relative improvement of these individual technical changes in the treatment of all-sky AMSU-A data is primarily judged against short-range forecast fits to other observations.