1. Nansen Environmental and Remote Sensing Center, Edvard Griegsvei 3a, 5059 Bergen, Norway.
2. Geophysical Institute, University of Bergen, 5007 Bergen, Norway.
3. Nansen International Environmental and Remote Sensing Center, Korpusnaya ulitsa 18, 197110 St. Petersburg, Russia.
4. Department of Geography, University of Bergen, Breiviksveien 40, 5045 Bergen, Norway.