The results of multi-year satellite monitoring of ice cover in the Caspian Sea are presented. The basis of the study was remote sensing data in the optical range, such as Sentinel-2 MSI, Landsat-8 OLI, Landsat-7 ETM+, Terra/Aqua MODIS, as well as archival Landsat-5 TM data. Also, Sentinel-1 SAR-C and archival ERS-1/2 SAR and Envisat ASAR radar data were used. The main objectives of the study were: determination of areas occupied by ice, identification of trends in ice formation and clearing periods, their inter-annual variability. To solve the problem of determining the parameters of ice cover, we used the multisensory approach whenever possible, i.e. comprehensive integrated analysis of heterogeneous data. The analysis of a vast array of satellite data, differing in nature and spatial resolution, and ice mapping was carried out using the toolkit of the See the Sea (STS) information system developed at the Space Research Institute of the Russian Academy of Sciences (IKI RAS). STS enables working with multi-year archival data, conduct joint analysis of different satellite data together with hydrometeorological information. It was found that during the study period, from the 1998-1999 winter to the present time, the largest area of ice cover of over 90,000 sq. km was observed in the 2011/2012 winter period. Ice was observed even in the bays of the Southern Caspian. Another direction of research, the results of which are presented, is the identification of capabilities and limitations in the use of satellite data obtained in different ranges (radar and optical) and at different polarizations.
|