COMPACT OCEAN WIND VECTOR RADIOMETER (COWVR): LONG-TERM SENSOR PERFORMANCE AND ENVIRONMENTAL DATA PRODUCTS

F. Polverari¹, M. G. Morris¹, S. T. Brown¹

¹Jet Propulsion Laboratory, California Institute of Technology

The Compact Ocean Wind Vector Radiometer (COWVR) is the first space demonstration of a low-cost, small-sat compatible conical microwave imager for atmospheric and surface observation, specializing in ocean vector winds. Heritage conical microwave imagers, such as SSM/I, AMSR, WindSat, GMI, and WSF-M have been providing important Earth observations for over 45 years, including but not limited to surface wind vector, atmospheric and surface temperature, water vapor, clouds, precipitation, snow and sea ice. However, due to the cost and complexity of these legacy systems, the ad hoc international constellation is dwindling, extending re-visit times, impacting weather forecasting. The objective of the COWVR mission is to demonstrate that a new, lower-cost radiometer architecture can perform as well as the legacy systems.

COWVR was deployed on the International Space Station (ISS) in January 2022 as a part of the Space Force Space Test Program (STP-H8) mission along with the TEMPEST-H8 microwave sounder. TEMPEST-H8 provides retrievals of vertical water vapor profiles and ice cloud properties, including convective intensity. The COWVR sensor provides fully polarimetric passive microwave observations at 18.7, 23.8, and 33.9 GHz, from which, ocean wind vector, precipitable water vapor, and cloud liquid water path can be estimated. The design of the COWVR instrument leverages the Electronic Polarization Basis Rotation (EPBR) technique in order to simplify the mechanical design and is calibrated using internal polarimetric sources resulting a 360o un-blocked conical scan (similar to SMAP). The un-blocked scan enables views in both the fore and aft directions from the spacecraft—giving two looks at the Earth scene—which enables higher skill in the wind vector retrieval. Utilizing two-look capabilities lessens the need for numerical weather prediction-based ambiguity removal—typically relied upon in a single-look observation geometry (such as WindSat).

We present the detailed in-flight performance characterization from over 3-years of operation of COWVR and TEMPEST-H8, focusing on the wind vector, water vapor, precipitation and cloud water products, demonstrating a compact sensor can perform as well as current generation operational sensors. The validation of the COWVR wind vector retrievals is carried out with respect to the Advanced Scatterometer (ASCAT)-B and ASCAT-C, with co-locations made within 25km and ± 30 minutes of each other. The ASCAT wind vector retrievals are obtained from the operational near real time products developed by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Ocean and Sea Ice Satellite Application Facility (OSI SAF), through the Royal Netherlands Meteorological Institute (KNMI). All COWVR data products can be downloaded from the Physical Oceanography Distributed Active Archive Center for research community use.

The work described in this abstract was carried out by the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. © 2025 California Institute of Technology. Government sponsorship acknowledged