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Introduction

 

Results of the search for the multiyear sea ice objects for deployment of the North Pole drifting station 36 during the field campaign 2008 using ENVISAT WSM and GMM imagery

Vasily Smolyanitsky(1), Vladimir Bessonov(1) and Vladimir Sokolov(1)

(1) Arctic and Antarctic Research Institute, 38 Bering str., 199397 St.Petersburg, Russian Federation

Abstract

We discuss results of the interpretation and field validation of the ENVISAT SAR imagery aimed on the search and track of the multiyear sea ice objects in the Arctic Basin for the purposes of the manned stations deployment during year 2008 field season. Drifting sea ice objects which are formed in the area of the Canadian Archipelago either as ice islands calved from its glaciers or floes broken from the thick (more than 5-6 meters) multiyear fast ice in its fjords and channels, are ideal sites for deployment of drifting stations and camps due to their much greater thickness in comparison to multi-year ice of the other originating places (e.g. Eurasian Arctic). Though quite scarce (order of several tens for one year) and difficult to find, during 1950s-1980s the ice islands were used several times in Russian and USA practices to deploy drifting stations and camps, and were found out and tracked with a help of routine and tailored ice air reconnaissance. In other cases very thick multiyear ice floes were searched and tracked by the same means. Since 1992 the ice air reconnaissance in the Arctic Ocean is carried out quite seldom by the Russian ice service, so that the high resolution satellite imagery, both visible, infrared and microwave, is the only possible mean to search for and track such sea ice objects. Operational experience of the Arctic and Antarctic Research Institute (AARI) of Roshydromet during the field seasons since 2004 showed the principal possibilities of using ENVISAT ASAR and EOS MODIS to identify and track positions of the ice islands and thick multiyear floes using their distinct differences in brightness and texture from the surrounding ice. ASAR GMM and WSM imagery are obtained directly from the ESA servers or in case of the field conditions with reduced resolution via the POLARVIEW portal of the Danish Technical University; MODIS 250 m resolution imagery is obtained from the AARI receiving station or NASA MODIS Rapid Response System portal. Search for potential sites for the current North Pole drifting station NP-36 was started in February 2008 using ENVISAT daily GMM and WSM mosaics and ice charts so that several groups of the objects identified as either ice islands or thick multiyear floes of Canadian Archipelago origin, were found out in early April and since that time and till August 2008 were tracked by their special features using available ENVISAT WSM and EOS MODIS scenes. Using the latest interpreted WSM scenes for the period 13-28 August the AARI research expeditionary vessel “Akademik Fedorov” successfully entered the area of the objects propagation at 82-83ºN 175ºE-175ºW (northward of Vrangel Island) and with a help of helicopter reconnaissance and validated the original imagery and found out the most suitable site for the NP-36 station (started operating on September 7th ). In-situ sampling showed that these objects, though not being the ice islands, were vast and giant floes composed of multiyear ice which survived more than 3-4 cycles so that their special features on the ENVISAT imagery were both due to their much higher average thickness (more than 4 meters), higher ridges and hummocks concentration and height (with correspondent much higher thickness under the hummocks) and possible differences in texture from the surrounding first and multiyear year. More information is expected in the course of the NP-36 scientific activity during the winter season 2008/2009.

 

 

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