1. Institute for Geophysics The University of Texas at Austin Austin Texas USA
2. Geophysical Institute University of Alaska Fairbanks Fairbanks Alaska USA
3. Department of Geological Sciences University of Texas at Austin Austin Texas USA
4. Center for Remote Sensing of Ice Sheets The University of Kansas Lawrence Kansas USA
5. Now at Division of Hydrologic Sciences Desert Research Institute Reno Nevada USA
6. Department of Earth System Science University of California Irvine California USA