Antarctica on the scales: Present-day mass balance of the Antarctic Peninsula from time-variable gravity field measurements

The subject of this study is the present-day ice mass balance of the Antarctic Peninsula using time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) complemented by data from in situ GPS sites and altimetric missions such as EnviSat, CyroSat and ICESat. This region is amongst the fastest warming regions on Earth and dramatic changes have been occurring over the past few decades, including the complete collapse of several ice shelves. Every 30 days GRACE delivers a gravity field with information at spatial scales down to ~400 km, with an accuracy approaching 2 cm of water. Over Antarctica GRACE will capture ice mass changes, although these will be contaminated by mass variations in the atmosphere, in nearby oceans, and due to post-glacial rebound (PGR) in the solid earth. Due to its relative ease of access, the Antarctic Peninsula is relatively well-known as regards atmospheric pressure and oceanic mass variations although numerical ocean tide models are still largely unverified in this region and errors will alias into the GRACE time series. The research will therefore focus on i) PGR measurements using new and existing Global Positioning System (GPS) observations to constrain rebound models; ii) verification of numerical tide models using onshore GPS ocean tide loading deformation estimates followed by application to the GRACE time series; and iii) the determination of seasonal and secular rates of ice mass change using corrected GRACE measurements; with iv) enhancement from radar and laser altimetry as appropriate. These will provide independent constraints on the effects of a warming climate on the Antarctic continent.