Slepian Basis Approach for GRACE Measurements Reveals Mass Loss in the Canadian Arctic Archipelago

Abstract:

Space borne gravity measurements collected by the Gravity Recovery and Climate Experiment (GRACE) have proven applicable in studying a wide variety of topics such as groundwater levels, glacial isostatic adjustment, ocean bottom pressure, sea level rise, and mass balance of glaciers and ice sheets. Due to GRACE's spatial resolution and associated leakage, applications have been limited to broad regional locations. Recent studies have improved upon the accuracy and spatial resolution to generate an orthogonal, band-limited basis over the particular region of interest, using an approach known as the Slepian basis method. While this and other GRACE based methods have been conducted over Greenland and Antarctica for mass balance estimations, little research has been devoted to measure mass variations of the Canadian Arctic Archipelago (CAA). Because of Baffin and Ellesmere's proximity to Greenland and the spatial resolution of GRACE, observed signal from the CAA glaciers and the Greenland ice sheet blend together. Preliminary results using a point source method indicate upwards of 850 Gt mass loss in the CAA between March 2002 and May 2015 with an average rate of about -70 Gt/yr. We leverage the Slepian basin approach and exploit the updated ICE-6G glacial isostatic adjustment model to better differentiate between these two signal sources and estimate the mass balance of the Canadian Arctic Islands with greater confidence and a higher accuracy. This improved determination of regional mass balance better constrains CAA's contribution to global sea level rise and the methods developed here can be employed in other locations and processes of interest.