Background

The Airborne Topographic Mapper (ATM) is a scanning LIDAR developed and used by NASA for observing the Earth's topography for several scientific applications, foremost of which is the measurement of changing arctic and antarctic icecaps and glaciers. It typically flies on aircraft at an altitude between 400 and 800 meters above ground level, and measures topography to an accuracy of ten to twenty centimeters by incorporating measurements from GPS (global positioning system) receivers and inertial navigation system (INS) attitude sensors.

The ATM instruments commonly fly aboard the NASA P3-B based at Wallops Flight Facility, Virginia, and have also flown aboard several twin-otter (DHC-6), C-130, and other P-3 aircraft. A major task of the ATM since 1993 has been the measurement of the Greenland ice sheet with the goal of determining changes in the ice sheet elevation. Other uses have included verification of satellite altimeters , and the measurement of sea-ice thickness. The altimeter often flies in conjunction with other instruments, and has been used to measure sea-surface elevation and ocean wave characteristics. New applications are always being investigated.

*** As of Jan. 1, 2009 GPStime = UTC + 15sec ***