Ice Cover of Eurasian Water Bodies and Rivers from Satellite and In Situ Observations
Kouraev, Alexei1; Shimaraev, M.N.2; Remy, F.3; Naumenko, M.A.4; Zakharova, E.A.3; Suknev, A.5
1LEGOS/University of Toulopuse III, FRANCE; 2Limnological Institute, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russia, RUSSIAN FEDERATION; 3CNRS; LEGOS, F-31400 Toulouse, France, FRANCE; 4Limnology Institute of the Russian Academy of Sciences, St. Petersburg, Russia, RUSSIAN FEDERATION; 5Great Baikal Trail Buryatiya, Ulan-Ude, RUSSIAN FEDERATION

A. V. Kouraev1,2, M.N. Shimaraev3, F. Rémy1,4, M.A. Naumenko5,, Zakharova E.A.1,2, A. Suknev6 1) Universite de Toulouse; UPS (OMP-PCA), LEGOS, 14 Av. Edouard Belin, F-31400 Toulouse, France 2) State Oceanography Institute, St. Petersburg branch, Russia 3) Limnological Institute, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russia 4) CNRS; LEGOS, F-31400 Toulouse, France 5) Limnology Institute of the Russian Academy of Sciences, St. Petersburg, Russia 6) Great Baikal Trail Buryatiya, Ulan-Ude, Russia Because of its response to regional and global variations in the climate system, arctic and sub-arctic lakes and internal seas are not only an integrator of climate processes, but also strong indicator of existing or potential change. It is important to well understand what are temporal and spatial scales of variability of natural parameters, what are teleconnections, feedbacks and mechanisms responsible for the changes, what are natural and anthropogenic causes of recent and historical changes in the hydrophysical and meteorological parameters. Changes in natural parameters are important for human activity (navigation, transport, fisheries, tourism etc) and affect large population living around. We present studies of ice and snow cover of continental water bodies and rivers using the synergy of more than 15 years-long simultaneous active (radar altimeter) and passive (radiometer) observations from radar altimetric satellites (TOPEX/Poseidon, Jason-1, ENVISAT and Geosat Follow-On) complemented by SSM/I passive microwave data. Five largest Eurasian continental water bodies - Caspian and Aral seas, Baikal, Ladoga and Onega lakes, and the Ob' river in the Western Siberia are selected as examples. An ice discrimination approach based on a combined use of the data is presented, as well as validation of this approach using in situ and independent satellite data in the visible range. We then analyse the long-term evolution of ice conditions for the lakes and inland seas using historical data and recent satellite observations. We also present our results of the field studies on the lakes Ladoga and Baikal. We address another interesting natural phenomenon - formation of giant rings on Baikal Lake ice. These rings (diameter 5-7 km, thickness of dark layer - 1 - 1.8 km) have perfect circular shape. The rings have been observed since the early 1970ies by satellite imagery in various regions of the lake. We present several existing hypotheses of the origin of these rings and discuss strengths and weaknesses of each hypothesis. We present observation of the formation, development and disappearance of these rings using various satellite data. We discuss the conditions needed to create and maintain these rings, the timing of and duration of their existence, as well as horizontal and vertical structure of ice and snow cover and of temperature and conductivity before and during the appearance of rings. This research has been done in the framework of the Russian-French cooperation GDRI "CAR-WET-SIB", CNES TOSCA AO, CNRS-Russia "Franco-Siberian Center for Research and Education" and PICS BALALAIKA, ESA Proposal C1P.13132, Russian FZP 1.5 and EU FP7 "MONARCH-A" projects.