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UP: Fachverband Umweltphysik

UP 3: Kryosphäre

UP 3.7: Talk

Tuesday, March 14, 2017, 14:15–14:30, GW2 B3009

Atmospheric Correction of Sea Ice Concentration Retrieval of 89 GHz AMSR-E Observations — •Junshen Lu, Georg Heygster, and Justus Notholt — University of Bremen, Institute of Environmental Physics, Otto-Hahn-Allee 1, 28359 Bremen, Deutschland

An improved sea ice concentration (SIC) retrieval algorithm named ASI2 using weather corrected polarisation difference (PD) in brightness temperatures (TBs) at 89 GHz measured by AMSR-E is developed. Effects of wind, total water vapour, cloud liquid water and surface temperature on the measured TBs are evaluated through a fast radiative transfer model, and corrected by simulating changes in TBs caused by the atmospheric influences using reanalysis data fields as atmospheric profiles. ASI2 is tested on (i) a validation dataset called Round Robin Data Package (RRDP) consisting of TBs measured by AMSR-E over pure surface types of open water and 100% SIC, and (ii) AMSR-E Level 2A re-sampled swath data from 2008. The correction on the RRDP dataset significantly reduces both standard deviation and bias in SIC over open water throughout the year, yet causes higher bias in summer over consolidated ice possibly due to melt ponds. A qualitative comparison with MODIS images shows that ASI2 using AMSR-E swath data resolves a more realistic ice gradient across the ice edge than the original ASI algorithm. In March 2008, the ASI2 SIC is about 10% to 35% higher than ASI along the ice edges.