Arctic Ocean Sea Ice Thickness and Kinematics SATELLITE RETRIEVALS AND MODELING

Sea ice in the Arctic Ocean ranges from thin new ice to thick deformed ridges. Changes in thickness are due to melting and freezing, and to physical rearrangement of existing ice to form leads and pressure ridges. As a brittle solid, fractures are created when the ice cover moves and deforms. Openings along fractures are sites of local heat exchange between the atmosphere and ocean, and of local ice production in the winter as ocean water freezes when exposed to the colder atmosphere. Closing of the ice forces it to raft or pile up into pressure ridges and to be forced down into keels, increasing the volume of sea ice that can be stored within a given area of the Arctic Ocean. This mechanical redistribution of sea ice affects ice strength and has a profound impact on ice behavior over a wide range of temporal and spatial scales. Accurate observation and simulation of the relative contributions of thermodynamics and dynamics to ice thickness distribution are thus critical for understanding the ice cover in terms of how it changes, and its vulnerability in a warming climate. Recent satellite altimetry and high-resolution synthetic aperture radar imaging have provided near-basin-scale views of ice thickness and motion for use in quantifying changes, and for assessment and refinerneut of models. During this coming decade, several satellite missions are poised to provide improved, coordinated, and near-continuous measurements of thickness and motion that will advance our understanding of Arctic ice cover. Here, we provide an overview of our current capabilities and the future prospects for observing these parameters from space.