Laser Monitoring of Ice Elevations and Sea-ice Thickness in Greenland

A low-cost Twin-Otter based laser altimetry and scanning system have been set up by KMS in several different commercial aircraft, and flown extensively in connection with airborne gravity activities in the Arctic Ocean north of Greenland, as well as on various research projects on the ice sheet and coastal glaciers in Greenland. The hardware system is based on a Riegl laser swath scanner or Optech laser altimeter combined with numerous GPS receivers. Roll and pitch are provided by either a medium-grade commercial INS or a low-cost custom-made IMU with fiber-optics gyros. The whole system is designed for use on non-dedicated aircraft, with a minimum of set-up time. In the paper we outline the hardware setup, processing schemes and give some examples of field campaigns and estimated accuracies. Measurements over sea-ice in the Polar Sea north of Greenland have shown that sea-ice freeboard can readily be measured combining laser altimetry and a local geoid model, yielding an indirect measurement of sea-ice thickness. Over land ice laser results have, a.o., been used to study radar penetration effects of airborne SAR interferometry, showing large height-dependent variations, corresponding to changes in snow facies.