Assimilation system preliminary assessment for additional EarthCARE obs: Doppler velocity, cloud extinction, Rayleigh backscatter

The report provides a preliminary assessment of the potential for additional EarthCARE observations — those in addition to cloud radar reflectivity and lidar attenuated cloud backscatter — to be included in the ECMWF data assimilation system for monitoring and potential assimilation. The main additional observations considered are radar Doppler velocity, lidar Rayleigh backscatter and lidar cloud extinction. The potential information content of each observation type will be discussed with reference to the Jacobians of the observation operators, which provide the sensitivity of the simulated observations to changes in the model state. Next, the impact of the new observation types will be investigated using single-cycle single-observation-type assimilation experiments. Investigating the impact of assimilating lidar cloud extinction will be taken further through a one-month Observing System Experiment (OSE), where cloud extinction is included in one-month of cycling assimilation experiments. Finally, the potential for observation quality monitoring of solar radiances is discussed.