Ice Cover of Eurasian Lake and Inland Seas from Satellite and In Situ Observations
Alexei V. Kouraev1,2, Mikhail N. Shimaraev3, Frederique Remy1,4, Nelly M. Mognard1,5, Peter I. Bukharizin6, Mikhail A. Naumenko7, Andrey Yu Ivanov8
1Universite de Toulouse; UPS (OMP-PCA), LEGOS, Toulouse, France; 2State Oceanography Institute, St. Petersburg, Russia; 3Limnological Institute, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russia; 4CNRS; LEGOS, Toulouse, France; 5CNES; LEGOS, Toulouse, France; 6Astrakhan expedition base of the Water Problems Institute of Russian Academy of Sciences, Astrakhan, Russia; 7Limnology Institute of the Russian Academy of Sciences, St. Petersburg, Russia; 8P.P.Shirshov Institute of Oceanology, Moscow, Russia

We present studies of ice and snow cover of continental water bodies 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 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 these lakes and inland seas using historical data and recent satellite observations.

We also address another interesting phenomenon - formation of giant rings on Baikal Lake ice. These rings (diameter 5-7 km, thickness of dark layer - 1 - 1.8 km) have almost perfect circular shape. The rings have been observed since the early 1970ies by various satellites and sensors (AVHRR, MODIS, Landsat, SPOT) in various regions of the lake. We present several existing hypotheses of the origin of these rings including gas emission, heat flux, cyclonic subsurface currents and mega-bubble formation due to gas seepage and discuss strengths and weaknesses of each hypothesis. We present observation of the formation, development and disappearance of these rings using optical and infra-red imagery (MODIS, Landsat), complemented by SAR imagery. 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 before and during the appearance of rings.

This research has been done in the framework of the Russian-French cooperation GDRI CAR-WET-SIB, French CNES TOSCA AO and FP7 MONARCH-A project.

Keywords: Lake and sea ice; Giant ice rings; Active and passive microwave remote sensing; Climate changes

Biography: He has a Ph.D. in oceanology from the Moscow Lomonossov State University, Russia. Now he is working in the field of continental hydrology (lakes, rivers, bogs, snow cover) using satellite observations, in situ data and numerical modelling.