IGPP Seminar Series

Monitoring ice sheets mass variations from GRACE

by Isabella Velicogna
JPL

Abstract

The Antarctic and Greenland ice sheets are home to the largest fresh water reservoirs in the world. Any substantial changes in the size of the ice mass could have important effects on global sea level, ocean circulation and climate. We used gravity field data obtained by the dual satellite Gravity Recovery And Climate Experiment (GRACE), to observe the fluctuations in The gravitational field generated by Greenland's and Antarctica's ice Sheet from 2002 to 2006. The gravitational variations were then used To determine the total mass of the ice sheet. Measuring the mass of the Ice sheets has been attempted by several other techniques, but has Proven difficult due to the complexity of measuring such a large area in a uniform manner. The use of GRACE, avoids those difficulties by measuring mass changes over the entire ice sheet. GRACE generates a new independent and powerful estimate of the polar ice sheet mass balance. Both ice sheets display a large mass imbalance during the analyzed period. The mass of the Antarctica ice sheet decreases significantly from 2002 to 2006. Most of this mass loss is generated by the West Antarctic Ice Sheet. The Greenland ice sheet display significant mass loss during the same period, with most of the signal coming from the South East glaciers. The uncertainty estimates for both Greenland and Antarctica are dominated by the effects of GRACE measurement errors and errors in our Glacial Isostatic Adjustment (GIA) correction. This lecture will provide a detailed analysis of results and will summarize the exciting contribution that time variable gravity can provide to improve our understanding of climate change.
Tuesday, 15 May 2007
3853 Slichter Hall
Refreshments at 3:45 PM
Lecture at 4:00 PM