Gravity anomalies and sea ice thickness in the Arctic Ocean from ICESat

Abstract

The ICESat laser altimetry mission has since January 2003 provided satellite altimetry over the ice-covered Arctic Ocean up to 86°N. The laser altimetry surface elevation data is the sum of geoid, sea ice freeboard and ocean mean dynamic topography, but by a combination of lowest level filtering and GRACE-based geoid models the signals may be separated, and sea ice thickness and gravity field information be recovered. In the paper we derive an improved gravity anomaly field for the Arctic Ocean using FFT Wiener filtering methods. The composite ICESat gravity grid shows all the major tectonic features of the Arctic Ocean at high resolution. The results are compared to the recently revised Arctic Gravity Project anomaly grid and airborne gravity. The results show that the laser altimetry data may provide excellent gravity results comparable to open ocean altimetry even over the most heavy ice conditions.