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Summary of Working Paper No. 3-1994

I.4.2: Ice Monitoring by Non-Russian Satellite Data. Phase 1. Feasibility Study.

By Stein Sandven, Nansen Environmental and Remote Sensing Center, Norway

Today several operational satellites provide data which can be used for ice monitoring of the Northern Sea Route. The satellite data cover regions from several thousand km to a few hundred. The spatial resolution varies from 30 km to 30 m. For several decades optical instruments with resolution of 1 km have been used in ice mapping, but these data can only provide useful information during cloud-free conditions. During the last few years a general trend in ice monitoring has been to use microwave remote sensing techniques, both passive and active instruments which are independent of cloud and light conditions. Especially Synthetic Aperture Radar (SAR) is a promising instrument which can be used to map different ice types in detail. The European Space Agency's satellite ERS-1, which has been operational since August 1991, has obtained thousands of SAR images globally. In the Kara Sea region, NERSC is performing ice monitoring using SAR images from the ERS-1 in combination with other satellite data. One of the objectives is to demonstrate near-real SAR time ice monitoring to assist Russian icebreakers in ice navigation. Up to now two demonstrations have been carried out where SAR images have been sent out to icebreakers by telefax. The plan is to incorporate SAR images from non-Russian satellites in the Russian Ice Service within a few years. The SAR coverage by ERS-1 is limited to 100 km wide areas repeated at 3-day intervals. In 1995 several SAR satellites will be in operation, and the Canadian Radarsat will provide up to 500-km wide SAR swaths. This will enable regular ice monitoring by SAR of most of the NSR.

An example of a SAR image (see the following page) from the mouth of Yenisei river shows the ice condition on March 23 1994. The track in the ice made by icebreakers going up the river to Dudinka is clearly shown in the image. The SAR image also shows individual ice floes and areas of thin ice which are only a few days old.