Mapping of sea ice around Greenland using near simultaneous ERS -1/2 and Radarsat data

Rashpal S. Gill		Danish Meteorological Institute, Lyngbyvej 100, DK 2100 Copenhagen, Denmark. email: rsg@dmi.min.dk http://www.dmi.dk
Poul Nielsen		Danish Meteorological Institute, Lyngbyvej 100, DK 2100 Copenhagen, Denmark. email: pon@dmi.min.dk http://www.dmi.dk
Hans H. Valeur		Danish Meteorological Institute, Lyngbyvej 100, DK 2100 Copenhagen, Denmark. email: hhv@dmi.min.dk http://www.dmi.dk

Abstract

The operational mapping of sea ice for the safety of navigation in the Greenland waters has traditionally been carried out using aerial reconnaissances and more recently NOAA -AVHRR images. However, bad weather restricts observations from the air and similarly cloud cover and to some extent insufficient sun light limit the use of AVHRR images. To minimize the need for air observations imagery from cloud and sun light independent systems such as from the SAR's on board the ERS -1/2 and more recently from Radarsat are being evaluated. The evaluation method involves comparing the signatures of sea ice in the SAR images with near simultaneous aerial photographs, video recordings and the ice charts produced by visual observations and using the mapping radar on board the aircraft. The results of the comparison has shown that for waters off Cape Farewell (60 N, 44 W), which are navigationally most important and which are characterised by thick ice floes of size 100 m, that during stormy weather, which is frequent, it is virtually impossible to distinguish between the open water and the regions of ice with concentration 3/10. At higher latitudes, for example off Disko Bay (70 N, 55 W) and Scoresby Sound (71 N, 24 W), which lie along the west and the east coasts, respectively, the ERS.SAR and Radarsat images are excellent for mapping the sea ice. The evaluations carried out so far indicates that the number of aerial observations made to map the sea ice can be significantly reduced. In the paper the results of the evaluations of the ERS.SAR images, which have been carried out as part of the pilot project PP2-DK2-AO2, and those from the Radarsat will be presented.

Keywords: ERS-1/2, SAR, Radarsat, ice mapping, Greenland.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry