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

With the introduction of improved data assimilation methods around the turn of the millenium, direct assimilation of cloud and precipitation observations became more feasible. Since then, ECMWF-JCSDA workshops have been held every 5 years to assess and progress the state of the art. This talk will overview past progress and introduce the current workshop and its key questions. These are: (1) the observing system, progress in operational all-sky assimilation from nowcasting to global weather forecasting, and the exploitation of a wider array of novel observations including cloud and precipitation lidar, lightning and passive sub-millimetre; (2) progress in cloud micro- and macro-physical modelling - to find out how the models can help constrain observation operators, and how much the observations can help better constrain the models; (3) progress in cloud and precipitation-capable observation operators, particularly the need to handle macrophysical details such as 3D effects and cloud overlap, and microphysical details including the shape, orientation and size distributions of hydrometeors; (4) improved methods for data assimilation, particularly as cloud and precipitation observations challenge many of the assumptions made in current operational systems, particularly the Gaussian and linear assumptions.