G‐band Differential Absorption Radar with Doppler

• Subject Area: Atmospheric Science, Oceanography and Climate Research
• Term: Funded in 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 502048393

Our understanding of the atmospheric water cycle is fundamental for our ability to predict weather and climate. However, due to the complex nature in particular of the atmospheric boundary layer and cloud microphysics severe gaps about the vertical water vapor distribution and the condensate load of clouds exist. This is of strong concern in respect to the response to climate change especially in sensitive areas with few observations such as the Arctic or other desert regions. Recently differential absorption radar (DAR) has been proposed to close the gap on in-cloud water vapor measurements and first ground-based test measurements were performed as proxy for a future space-borne mission by NASA. DAR uses the differential absorption at the 183 GHz water vapor line, the so-called G-band, which has previously not been used for atmospheric research. Theoretical work by the proposers shows the large benefit of DAR also for ground-based and airborne measurements. Our particular interest is in the Arctic where moisture inversions and mixed phase clouds are still posing strong challenges. Applying DAR on an airborne platform for the first time in the Arctic will enable new insights into water vapor distribution but also on mixed-phase clouds especially in combination with radar at different frequencies. Multi-frequency radar measurements are able to reveal different hydrometeor properties but including G-band to the usual combination of X-, K-, and W- band is still in its infancy. Therefore, we aim for an instrument with full Doppler capability enabling for the first time such ground-based measurements to enhance the understanding of cloud microphysical processes. Microwave remote sensing is a key expertise at the University of Cologne having developed new techniques, operating ground- and airborne instruments in various regions and exploiting the measurements also in cooperation with many groups worldwide. We plan to use the new G-band Radar for Water vapor profiling and Arctic Clouds (GRaWAC) instrument on the Polar 5 aircraft and at the AWIPEV (Alfred Wegener Institute for Polar and Marine Research (AWI) and the French Polar Institute Paul Emile Victor (IPEV)) research station at Ny-Ålesund, Svalbard, as part of the Transregional Collaborative Research Centre TR172 “Arctic Amplification”. In this way the instrument shall become a key component for the third phase of TR172. Furthermore, we plan to deploy the instrument at the Jülich ObservatorY for Cloud Evolution (JOYCE) being part of the European Aerosol, Clouds and Trace gases Research Infrastructure (ACTRIS) to investigate the full benefit of sensor synergy at a typical mid-latitude site and in this way prepare for the next generation of ground-based monitoring systems.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Differentielles Absorptionsradar im G-Band mit Dopplerfähigkeit
• Instrumentation Group: 6670 Radaranlagen (außer Distanzmesser 062 und Doppler-Radar 664 und 886)
• Applicant Institution: Universität zu Köln
• Leader: Professorin Dr. Susanne Crewell