Ice flux in the Fram Strait from ENVISAT ASAR data.
Stein Sandven(1) and Kjell Kloster(1)
Nansen Environmental and Remote Sensing Center,
The Fram Strait is the main area for sea ice and liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic. The sea ice flux is a key climate parameter which is monitored by Upward-Looking Sonars on fixed moorings at 79°N in the Fram Strait. Ice drift retrieval from satellite data has been done using passive microwave and scatterometer data, but the resolution and seasonal coverage of these data is not as good as for Wideswth SAR data. With regular use of wideswath SAR data, more accurate estimates of the area flux can be obtained.
Ice area flux in the Fram Strait derived from a sequence of ASAR images has started to be produced as a seasonal and interannual time scale. Starting in February 2004, NERSC has produced ice area flux profiles across 79 N using profiles of ice drift from SAR and ice concentration profiles from passive microwave data. The time interval between the images is normally 3 days. Data analysis for 2004 shows that SAR can be used throught the year to estimate uce drift in the Fram Strait. Scatterometer and passive microwave can be used for ice drift estimateion only in the winter season. Therefore, SAR ice drift monitoring can be a useful supplement to other established methods. The monitoring by SAR requires regular acquisition and production of ASAR wideswath data from ENVISAT and later from other SAR missions, such as RADARSAT-2.