HALO Microwave Package next generation - Sub-Millimeter Radiometer (HAMPng-SMR)

• Subject Area: Atmospheric Science
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531848096

We aim to complement HALO instrumentation by a novel sub-millimeter radiometer (SMR) which will extend the frequency range covered by the existing HALO Microwave Package (HAMP) to its next generation (HAMPng-SMR). In this way, we want to improve HALO’s capabilities to study clouds and precipitation – both being notorious difficult to represent in numerical weather prediction and climate models. Furthermore, exploring several water vapor channels will help to better understand water vapor in the upper troposphere lower stratosphere. HALO’s microwave measurements by HAMP (part of the Next-Generation Aircraft Remote Sensing for Validation (NARVAL) configuration) are currently limited to below 200 GHz, similar as today's satellite instruments. However, higher frequencies are becoming of increasing interest in passive remote sensing due to their unique feature to penetrate clouds further than classical visible and infrared measurements and at the same time be more sensitive to ice particles than microwave. Upcoming space missions will make use of this yet unexploited information, e.g., the Ice Cloud Imager (ICI) on MetOp-Second Generation (MetOp-SG) to be launched in 2026 and the Arctic Weather Satellite (AWS) envisioned as prototype for the EUMETSAT Polar System (EPS) – Sterna constellation of microsatellites sub-millimeter channels are also discussed for geostationary application to enhance global monitoring capabilities of precipitation. To fully exploit sub-millimeter measurements and built solid retrievals requires detailed information on the vertical hydrometeor distribution. Therefore, we propose HAMPng-SMR as a new amendment to the NARVAL configuration where the synergy benefit with cloud radar, lidar, thermal imaging and the novel proposed HELICS promises unique insights into clouds. HAMPng-SMR will be equipped with 14 frequencies between 183 and 448 GHz covering several water vapor absorption bands and window regions as foreseen for the upcoming satellites. The radiometer will be installed in the HALO Large Wing Pod (HLWP) looking down- and backward against flight direction with an incidence angle of 53° with the surface mimicking ICI. For calibration purposes and to guarantee proper instrument performance, a second aperture on top of the wing pod will be used for observing the quasi cosmic background as a cold target and/or stratospheric water vapor remote sensing. With its small footprint smaller (< 1 km) it will allow to assess spatial variability which is not resolved by satellites, i.e., 15 km for ICI. In summary, HAMPng-SMR will help to (i) gain valuable knowledge on ice cloud properties and humidity, (ii) support retrieval development, and (iii) serve as a validation platform for the satellite instruments.

• DFG Programme: Major Instrumentation Initiatives
• Major Instrumentation: HAMPng-SMR Radiometer
• Instrumentation Group: 6420 Meßempfänger, Feldstärkemeßgeräte
• Applicant Institution: Universität zu Köln
• Leader: Dr. Mario Mech
• Co-Investigator: Professorin Dr. Susanne Crewell