HR: 09:00h
AN: C21C-05    [Abstracts]
TI: A decade of sea ice thickness mapping by airborne lidar between Greenland and the North Pole
AU: Hvidegaard, S M
EM: smh@space.dtu.dk
AF: Danish National Space Center, Juliane Maries Vej 30, Copenhagen, 2200, Denmark
AU: * Forsberg, R
EM: rf@space.dtu.dk
AF: Danish National Space Center, Juliane Maries Vej 30, Copenhagen, 2200, Denmark
AU: Skourup, H
EM: hsk@space.dtu.dk
AF: Danish National Space Center, Juliane Maries Vej 30, Copenhagen, 2200, Denmark
AU: Stenseng, L
EM: stenseng@space.dtu.dk
AF: Danish National Space Center, Juliane Maries Vej 30, Copenhagen, 2200, Denmark
AU: Hanson, S
EM: sha@space.dtu.dk
AF: Danish National Space Center, Juliane Maries Vej 30, Copenhagen, 2200, Denmark
AB: Airborne laser altimetry provides a direct measurement of sea ice freeboard, when combined with a precise geoid model and a lowest-level filtering algorithm to take into account residual errors in GPS-positioning, ocean dynamic topography, tides etc. Using swath laser scanning, the method additionally gives detailed information on the geometry of leads, ridges and the distribution of thin ice and open water. The conversion of sea ice freeboard heights to thickness is based on the assumption of equilibrium, with major errors sources relating to snow depth and density of sea ice. In the paper we describe results of measurements with airborne laser north of Greenland, Ellesmere Island and in the Fram Strait region, carried out on a yearly basis since 1998, in the first years using a single beam laser, and since 2001 using swath laser scanning giving a resolution of approximately 1 m in the ice features. The campaigns have mostly been done in the spring period, typically in connection with airborne gravity surveys or CryoSat calibration and validation activities. Observed secular changes in the sea ice freeboard heights are masked by limited spatial and temporal extent of campaigns, as well as interannual variability in the sea ice regime of the region. To address the error sources in the lidar thickness determination, a number of in-situ and helicopter EM comparisons have been carried out, e.g latest in April 2007 around the Tara drifting station beyond the North Pole, as part of the Damocles project. In cooperation with ESA and APL, coincident Ku-band radar and laser systems have also been flown, giving a unique opportunity for airborne measurement of snow depth as well.
DE: 0750 Sea ice (4540)
DE: 0758 Remote sensing
DE: 1621 Cryospheric change (0776)
SC: Cryosphere [C]
MN: 2007 Fall Meeting