Combining the German national radar network with EarthCARE's Cloud Profiling Radar

The understanding of microphysical properties and processes in clouds plays a substantial role in the improvement of existing numerical weather models and forecasting. To gain access to these quantities deep within clouds, microphysical retrievals based on radar measurements are indispensable tools. Single-wavelength radar measurements, however, are not enough to properly constrain the microphysical properties of hydrometeors like size and shape alone and therefore need to be paired with other measurement techniques like multi-wavelength or polarimetric quantities. While polarimetric quantities are mainly useful from an oblique perspective, multi-wavelength or Doppler fall-speed observations are best made vertically. 

To tackle this observational dilemma, we combine data provided by the vertically pointing W-band Cloud Profiling Radar (CPR) carried on EarthCARE with data generated by the national German radar network operated by the Deutscher Wetterdienst (DWD) which consists of 17 polarization Doppler weather radars in the C-band covering whole Germany together. Vertical profiles from operational scans in range of EarthCare's overpasses are extracted at the position of the footprint of CPR following the recently developed Beam-aware Columnar Vertical Profile (BA-CVP) method. This measurement geometry grants the opportunity to combine multi-wavelength radar observations with Doppler fall-speed measurements and side-looking polarimetry for the possibility of constraining existing ambiguities concerning the microphysical properties of ice hydrometeors. 

The findings of this study in form of more accurate information about ice hydrometeors based on polarimetric multi-frequency radar measurements can ultimately be used to improve existing numerical weather models with regards to ice growth processes and their representation within the models. Naturally, similar studies can be done for any other operational radar network overflown by EarthCARE by adapting the BA-CVP method, opening the door for quasi-global dual-wavelength radar observations on an operational scale.