Laboratory for Satellite Altimetry / Sea Ice and Polar Dynamics Science Team

Validation Experiments

The sea ice validation experiments are used to assess how well sea ice elevation (and hence ice thickness) can be measured from space using satellite altimetry. Since 2002 we have conducted, jointly with NASA Goddard Space Flight Center, six aircraft field experiments to validate satellite altimetry data provided by the conventional microwave altimeters on-board ERS-2 and Envisat, as well as the Geoscience Laser Altimeter System (GLAS) on-board ICESat, and the advanced microwave satellite altimeter (SIRAL) system on-board CryoSat-2. More information about these experiments can be found by following the links to the left. Airborne surveys are carried out jointly with the NASA Operation IceBridge Mission using the NASA/Wallops Flight Facility P-3B aircraft, and the NASA DC-8, which over-fly the satellite ground-tracks. Flights and complimentary surface observations (if available) are near simultaneous with satellite over-passes to take account of the drift of the ice pack and ensure the highest quality data for comparison. Data collected during these aircraft missions are publically available via the IceBridge data products page at the National Snow and Ice Data Center (NSIDC).

Our objective of monitoring sea ice thickness and volume change from orbit is technically challenging owing to the small sea-ice freeboard signal and the complex distribution and density structure of sea ice and its snow cover. As a result a number of airborne observing systems are used to validate the satellite altimetry datasets. Airborne instrumentation includes: NASA's high precision, airborne scanning/profiling laser Airborne Topographic Mapping (ATM) system, the University of Kansas ultra-wideband "snow radar" to measure snow thickness on sea ice, a Digital Mapping System (DMS) comprised of a digital visible camera operating in continuous mode, and other airborne sensors such as an Electro-Magnetic ("EM Bird") system operated by the University of Alberta tethered beneath a second aircraft, the Land Vegetation and Ice Sensor (LVIS) airborne laser altimeter, and the KT-19 Pyrometer for measuring surface temperature. With the exception of the "EM Bird" system, this remote-sensing instrument suite is typically carried onboard the NASA P-3B or DC-8 aircraft as part of the NASA Operation IceBridge mission currently scheduled to run from 2009-2019. The EM Bird system is towed by a DC-3/BT-67 Basler from the Alfred Wegener Institute, Germany, which participates in ESA's annual CryoVEx airborne experiment in support of CryoSat-2 validation.