Satellite altimetric time series allow high-precision monitoring of ice-sheet mass balance.
Understanding elevation changes in these regions is important because outlet glaciers along ice-sheet
margins are critical in controlling flow of inland ice. Here we discuss a new airborne altimetry dataset
collected as part of the ICECAP (International Collaborative Exploration of the Cryosphere by Airborne
Profiling) project over East Antarctica. Using the ALAMO (Airborne Laser Altimeter with Mapping
Optics) system of a scanning photon-counting lidar combined with a laser altimeter, we extend the
2003–09 surface elevation record of NASA’s ICESat satellite, by determining cross-track slope and thus
independently correcting for ICESat’s cross-track pointing errors. In areas of high slope, cross-track
errors result in measured elevation change that combines surface slope and the actual z=t signal.
Slope corrections are particularly important in coastal ice streams, which often exhibit both rapidly
changing elevations and high surface slopes. As a test case (assuming that surface slopes do not change
significantly) we observe a lack of ice dynamic change at Cook Ice Shelf, while significant thinning
occurred at Totten and Denman Glaciers during 2003–09.