The Airborne Topographic Mapper (ATM) measures topography to an
accuracy of ten to twenty centimeters by combining measurements from
an airborne laser altimeter and GPS (global positioning system)
receivers. The ATM has demonstrated this accuracy at distances as
great as a thousand kilometers from any base station.
The current ATM instruments (ATM2 and ATM3) and their predecessors
have a history going back to the mid 1970's. The instruments commonly
fly aboard the NASA P3-B based at Wallops Flight Facility,
Virginia. ATM2 has also flown aboard several twin-otter (DH-6)
aircraft. A major task of the ATM over recent years 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. Measurement of coastal
beach dynamics and monitoring of beach erosion was begun in 1995 with
an initial airborne survey of northern Assateague Island in
conjunction with the National Park Service's ground-based monitoring
effort. Also, in 1994 an aerial survey was compared against the FAA
regulations to determine airfield obstruction clearances at the
Wallops Flight Facility.
[Summary provided by NASA]
