Seasonal Variations of Freshwater Composition of the Surface Desalinated Layer of the Kara Sea

Abstract We present the results of a study on the seasonal variability in the contribution of different freshwater sources to the formation of the surface desalinated layer (SDL) of the Kara Sea within one ice‐free period in 2021. We use direct measurements on physical and chemical properties of the investigated water. For the first time, a layer‐by‐layer calculation of the contribution of the Ob and Yenisei waters and sea ice meltwater (SIM) to SDL using a 4‐component mixing model is presented. We show that seasonal variability of chemical run‐off of the Ob’ and Yenisei Rivers strongly affects the chemical properties of the SDL. Also, the difference in the values of total alkalinity and dissolved silicates between the riverine waters of the Ob and Yenisei and SIM reveals freshwater origin. The fractions of Ob, Yenisei and SIM waters in the surface layer in different seasons vary within 5%–40%, 4%–55%, and 2%–26%, respectively. It has been shown that a redistribution of freshwater occurs within the SDL of the Kara Sea by the end of the ice‐free period.