EVALUATING CRYORAD PERFORMANCE REQUIREMENTS THROUGH 0.4–2 GHZ BRIGHTNESS TEMPERATURE SIMULATIONS WITH OCEAN–SEA ICE MODELS
Marzo 25, 2026SIXTEEN YEARS OF TOWER-BASED ELBARA-II L-BAND RADIOMETRY AT THE SODANKYLÄ SUPERSITE: FROM SOIL FREEZE/THAW TO FOREST CANOPY TRANSMISSIVITY ACROSS CONTRASTING BOREAL LANDSCAPES
Marzo 25, 2026A. Hossan1, A. Colliander2, S. Brown1, N. Schlegel3, J. Harper4, B. Vandecrux5, R. Cullather6,7
1Jet Propulsion Laboratory, California Institute of Technology, 2Finnish Meteorological Institute, Helsinki, Finland, 3NOAA/OAR Geophysical Fluid Dynamics Laboratory, Princeton, NJ, USA, 4Department of Geosciences, University of Montana, Missoula, MT, USA, 5Department of Glaciology and Climate, Geological Survey of Denmark and Greenland (GEUS), Denmark, 6NASA GSFC/GMAO Greenbelt, Maryland, United States, 7Univ. of Maryland at College Park, ESSIC, College Park, Maryland, United States
Polar ice sheets have become major contributors to global sea level rise, now losing mass over three times faster than in early 1990. Surface meltwater plays a critical role by altering the surface energy balance and enhancing ice flow via basal lubrication and hydrofracturing. In Greenland, surface melt accounts for over half of recent mass loss, while in Antarctica, it contributes to ice shelf weakening and dynamic instability. Recent increases in melting and refreezing have reduced firn pore space and created impermeable layers, enhancing lateral runoff and impacting surface mass balance (SMB). Accurate quantification of seasonal meltwater volumes and infiltration depths is essential for improving SMB estimates, firn densification modeling, and projections of sea level rise. However, significant uncertainties persist in model-derived estimates of liquid water content and percolation depth.
Microwave radiometry offers unique advantages for monitoring melt processes due to its sensitivity to liquid water and ability to provide frequent, all-weather, day-night observations. High-frequency channels (e.g., 18.7, 36.5 GHz) are sensitive to surface melt, while low-frequency channels, particularly L-band (1.4 GHz), offer greater penetration and sensitivity to subsurface liquid water. The upcoming ESA Copernicus Imaging Microwave Radiometer (CIMR) will, for the first time, provide multi-frequency (L- to Ka-band) coincident observations over the polar regions several times daily, enabling depth-resolved monitoring of firn meltwater.
We present a multi-frequency retrieval approach using L- to Ka-band observations from SMAP, SMOS, and AMSR2 to estimate daily meltwater amount and infiltration depth. Ground validation is performed using in situ data from PROMICE/GC-Net AWS (Greenland) and SCAR READER (Antarctica), along with firn models including locally calibrated energy balance models and the Ice-sheet and Sea-level System Model’s Glacier Energy and Mass Balance (GEMB) module. The resulting product provides twice-daily estimates of surface/subsurface freeze/thaw status, liquid water content, and wet layer thickness. Frequency-dependent sensitivity enables retrieval of vertical meltwater profiles, with high frequencies detecting surface melt and L-band capturing subsurface liquid water. Results show significant potential for improving monitoring of melt/refreeze dynamics and refining sea level rise projections.
