Sea Ice Thickness from Satellite Data and Its Recent Trends in Polar Regions

Sea ice thickness provides an integrated measure of changes in the surface energy balance. Sea ice also has profound socio-economic value due to its impact on transportation, hazards, recreation, fisheries, and hunting. With recent developments in remote sensing instrumentation and retrieval methods, it is now possible and practical to estimate sea ice thickness from space using a variety of techniques, each having distinct advantages and disadvantages. To take advantage of the relatively long record of optical (visible, near-infrared, and infrared) satellite data from the Advanced Very High Resolution Radiometer (AVHRR), an energy budget approach for estimating sea and lake ice thickness has been developed. This One-dimensional Thermodynamic Ice Model (OTIM) has exhibited acceptable accuracy and uncertainty when compared to other satellite-derived sea ice thickness datasets such as ICESat and CryoSat-2. These lidar and radar altimeters measure ice elevation (freeboard), from which ice thickness can be estimated. OTIM has been also validated with in situ sea ice thickness measurements and the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS). All approaches are influenced by uncertainties in the depth of snow on the ice, surface melt, deformation, ice motion, and other factors.

In this study we present and inter-compare sea ice thickness products from OTIM, ICESat, CryoSat-2, PIOMAS, and IceBridge aircraft. The comparisons are done over the Arctic Ocean for the period of overlap between all datasets. Additionally, OTIM is applied to 33 years of AVHRR Polar Pathfinder-Extended (APP-x) data, 1982-2015, to generate sea ice thickness for both the Arctic and Antarctic. Given the significant changes in sea ice cover in recent decades, we address the question of how sea ice thickness and volume have changed. Possible relationships with the Arctic Oscillation, North Atlantic Oscillation, and the Cyclone Activity Index (CAI) will also be discussed.