Climate model PArameterizations informed by RAdar (PARA)

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PARA contributes to the 2nd objective of SPP PROM by improving cloud and precipitation schemes in atmospheric models via the exploitation of polarimetry. An adequate representation of moist diabatic processes in clouds and precipitation in climate models is challenging, because these spatially unresolved processes are subject to sub-grid parameterizations, which must be informed by observations and/or models resolving these processes. Radar polarimetry provides most suitable observations on cloud and precipitation microphysics via microphysical retrievals and process fingerprints. PARA will focus in Phase I of PROM on ice water content heterogeneityand precipitation generation via the ice phase and concentrate on mixed-phase processes including riming and the role of particle number concentration variability in Phase II. PARA will investigate four processes both by polarimetric radar retrievals and the evaluation and revision of their representation in the ICON general circulation model (Fig. 1): (i) ice generation and spatial heteorogeneity of ice water content at ICON-GCM sub-grid scales, (ii) the role of both in snow formation like aggregation, (iii) melting of snow falling through the 0°C isotherm, and (iv) evaporation of rain below the melting layer.