Incorporating W‐Band Doppler Velocity Signal Simulator Into COSP2: Model Evaluation Against Ground‐Based Radar Measurement

Abstract A new signal simulator for Doppler velocity, derived for W‐band cloud profiling radar onboard EarthCARE, is developed and implemented into the Cloud Feedback Model Intercomparison Project Observation Simulator Package version 2 (COSP2). The simulator converts the vertical motion of hydrometeors and cumulus mass flux in global climate models (GCMs) into Doppler velocity signals, providing statistics on Doppler velocity and its spectrum width in the form of Contoured Frequency by tEmperature Diagram (CFED) or by Altitude Diagram (CFAD). To account for the different treatments of vertical air motion in stratiform and convective clouds within GCMs, their statistics are processed separately. The simulator was tested on the MIROC6 GCM and compared with ground‐based radar measurements. The results showed consistency in ice particle growth and melting between the model and the observations. However, the droplet fall speed in the model was quantitatively underestimated, revealing a bias in the cloud microphysics of MIROC6. The combined use of this simulator with calculation of cloud optical depth in COSP2 also allows for the investigation of Doppler velocity characteristics as a function of cloud type. The developed simulator enabled COSP2 to generate model diagnostics of cloud particles and cumulus vertical air motions, facilitating future global comparisons with EarthCARE data. The enhanced capabilities of COSP2 thus will add value to model evaluation through the combined use of multiple simulators and multi‐sensor synergistic observations provided by EarthCARE.