Tuesday, 19 October, 11:30 a.m. – 1:30 p.m.

Organizers: Tim Grow and Rao Yalamanchili

Speakers: John Wahr, University of Colorado

Topic: The GRACE Satellite Mission: Using Time-Variable Gravity to Study the Earth

Summary: NASA, in collaboration with the German Space Agency (DLR), launched the GRACE satellite gravity mission in Spring, 2002. The mission lifetime is presently projected to last through 2013. GRACE provides highly accurate monthly solution for the Earth's global gravity field.

Differences between these solutions gives information about time-variability in the gravity field, and so about month-to-month fluctuations in the Earth's mass distribution.

The data can be used to study a wide range of processes from many Earth science disciplines. They are providing information about changes in the storage of water and snow on land, ice mass loss in Antarctica and Greenland, changes in ocean bottom pressure and ocean mass variability, and processes in the solid Earth (e.g post-glacial-rebound; very large earthquakes).

This talk will describe the GRACE mission, and will include a representative cross-section of the kinds of things people are doing with GRACE data.

Biography: John Wahr received his undergraduate degree at the University of Michigan, and went from there to the University of Colorado where he received a PhD in Physics in 1979. After three years on a post-doctoral appointment at Princeton University, he returned to the University of Colorado in 1983, where he is presently a Professor in the Physics Department and a Fellow of the Cooperative Institute for Research in Environmental Sciences. John is a geophysicist, interested primarily in the detection and interpretation of geophysical signals in geodetic data. Over the last decade, John has been heavily involved in the GRACE satellite gravity mission, which is monitoring the Earth's global gravity field on a monthly basis, down to scales of a few hundred km.