1. Arctic and Antarctic Research Institute, 38 Bering str., 199397 St. Petersburg, Russia;
2. Nansen Environmental and Remote Sensing Center/Geophysical Institute, University of Bergen, Edvard Griegsvei 3A, N-5059 Bergen, Norway;
3. Nansen International Environmental and Remote Sensing Center, Korpusnaya str. 18, 197110 St. Petersburg, and Russia and Arctic and Antarctic Research Institute, 38 Bering str., 199397 St. Petersburg, Russia.