1. Department of Geography, George Washington University, Washington, DC20052, USA
2. Tyumen State University, Tyumen, Russia
3. Oil and Gas Research Institute of the Russian Academy of Sciences, Moscow, Russia
4. V.B. Sochava Institute of Geography, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
5. ARCTI Center, University of Northern Iowa, Cedar Falls, IA50613, USA