Konik A.A., Zimin A.V., Atadzhanova O.A.
The paper describes monthly and intra-seasonal dynamics of the major fronts in the River Plums and the Marginal Ice Arctic frontal zones in the Kara Sea in the warm period from July to September 2007 and 2011. Quantitative characteristics of these frontal zones are estimated. The sea surface temperature fields and the gradients calculated from them from the product GHRSST OSTIA Sea Surface Temperature and Sea Ice Analysis are used as the initial data. It is established that the frontal zones break up into separate contrast spots in the gradient field, and to separate them into the entire sea, aggregation of data over gradients and temperatures is required, which required the development of a separate technique. The complex structure of the frontal zones and the considerable spatio-temporal variability of the position of their main fronts are shown. Two main frontal zones are identified in the water area of the sea: the River Plums associated with the influence of the rivers Ob and Yenisei and the Marginal Ice Arctic front, connected with the melting of Arctic ice. In the conditions of the modern climate, a significant dynamics of the River Plums front variation and a relatively stable position of the Marginal Ice Arctic front are established. It is shown that the intra-seasonal dynamics in the Marginal Ice Arctic front increases to a peak in September and the River Plums front peaks in August. In other months, the seasonal dynamics is expressed in the meandering of the position of the Marginal Ice Arctic front and the River Plums front. It is revealed that in 2007 and 2011, with a minimum ice cover, the average temperature gradient inside the River Plums frontal zone was 0.029 °C/km, with a width of about 137 km, and in the Marginal Ice Arctic front — 0.027 °C/km with a width of almost 104 km.