Meeting Documents

Towards Improved Ocean and Sea Ice Estimates in the Polar Regions

Abstract

The behavior of the oceans and sea ice in the high latitude polar regions can be a harbinger of global climate change, but the spatiotemporal variability of such regions continues to be difficult to monitor and estimate. Both in situ and satellite observations in ice-covered regions can be challenging. In this work, we use available monthly estimates of sea surface height and freeboard based on ICESat-2, CryoSat-2 and other satellite altimeters, together with similar fields derived from state estimates produced by the project for Estimating the Circulation and Climate of the Ocean (ECCO), to assess the potential of such observations for constraining ocean and sea ice variability in polar latitudes. Such quest involves estimating data weights that can determine the importance of observational constraints in any optimization procedure. “Two-point” and “three-point” comparisons of various data sets and ECCO fields, together with simple assumptions of weak correlations between common signals and respective errors, yield estimates of the data weights that show substantial dependence on regions and datasets considered. In an ECCO optimization context, our estimates of uncertainty and inferred ECCO-data differences indicate that available freeboard observations can provide valuable constraints on the ocean-sea ice state estimates. Results for sea surface height are more mixed and suggest a relatively lower impact of those observations in constraining the ocean circulation in many ice-covered areas of both the Arctic and Antarctic.