Analysis of the Winter Hydrological Regime of the Yenisei, Pechora, and Khatanga Estuaries Using SMOS Data

Analysis of seasonal and interannual variations of the brightness temperature of the Yenisei, Pechora, and Khatanga estuaries is performed using the SMOS (Soil Moisture and Ocean Salinity) satellite MIRAS (Microwave Imaging Radiometer using Aperture Synthesis) data for the period 2012–2020. It is shown that during the freezing period, with low river flow, Khatanga and Pechora bays are strongly influenced by the salty waters of the Laptev Sea and the Pechora Sea, respectively. In Yenisei Bay, the analysis reveals two characteristic areas for the winter period, delimited by a narrow strait between Sopochnaya Karga and Oshmarin capes. In the southern part of the bay, the water remains fresh or slightly salty, while in the northern part (north of the Sopochnaya Karga post), the water is always brackish, as this is the mixing zone of the fresh water of the Yenisei River and the salty water of the Kara Sea. The sea areas adjacent to the Yenisei and Pechora estuaries (the Kara Sea and Pechora Sea, respectively) are dynamic zones with brackish or salty water and constantly breaking ice under the influence of hydrological and climatic factors. The results show that SMOS MIRAS data can be used to estimate water salinity and movement of the transition zone under the ice in large bays and estuaries; to analyze the stability and dynamics of the Arctic sea-ice cover; and to determine the beginning of ice melt in large sea and freshwater areas.