PRELIMINARY RESULTS OF SEA SURFACE SALINITY RETRIEVAL FROM MICAP COMBINED ACTIVE AND PASSIVE OBSERVATION
Marzo 25, 2026TOWARDS PHYSICALLY CONSISTENT COPERNICUS IMAGING MICROWAVE RADIOMETER LEVEL 2 PRODUCTS FOR THE GLOBAL OCEAN AND ATMOSPHERE
Marzo 25, 2026A. Hossan1, S. Kacimi1, S. T. Brown1, M. Morris1, F. Polverari1
1Jet Propulsion Laboratory, California Institute of Technology
For over four decades, spaceborne microwave sensors have been essential for monitoring changes in the polar sea ice covers. The European Space Agency’s upcoming Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) mission, scheduled for launch in 2027, will ensure the continual altimetric monitoring of the polar regions beyond the lifespans of current missions such as CryoSat-2 and ICESat-2. CRISTAL will carry a dual-frequency radar altimeter (IRIS) operating at Ku- and Ka-band, and the Advanced Microwave Radiometer (AMR-CR), developed at NASA-JPL, providing nadir radiometric observations across 18.7 to 166 GHz. AMR-CR’s primary functions are to correct radar propagation delays due to tropospheric water vapor and to support surface-type classification.
Sea ice concentration (SIC) and type are critical parameters for the processing of altimetric data over sea ice. This work presents updates on the CRISTAL AMR-CR Level 2 SIC and surface-type classification algorithms. Sea ice types exhibit distinct spectral signatures at Ku- and Ka-bands (e.g., gradient ratios such as GR1934) which can inform classification procedures. For SIC, we apply a frequency-based bootstrap algorithm utilizing AMR-CR’s low-frequency channels. To support pre-launch algorithm development, we use data from the radiometer aboard the Sentinel-6 satellite, which shares an identical design with AMR-CR. Sentinel-6, launched on November 21, 2020, operates in a non-sun-synchronous orbit (66° inclination), providing partial coverage of the Southern Ocean over first-year ice. To expand coverage over multiyear ice, we incorporate observations from the Advanced Microwave Scanning Radiometer 2 (AMSR2) onboard JAXA’s GCOM-W satellite. We derive instrument-specific tie points and prior probability density functions for gradient ratios over various surface types in both hemispheres, using synthetic and observed datasets. We present initial results on algorithm performance, validation, and uncertainty estimation, along with an overview of the processing workflow.
