Large Eurasian rivers (Ob, Yenisei, Lena and others) inflow to the Arctic Ocean and form large-scale river plumes. The resulting freshened surface layers located in the Kara, Laptev, and East Siberian seas are among the largest in the World Ocean, in total they cover up to one million square kilometers of sea area.

The freshened surface layer in the Laptev and East Siberian seas is formed mainly by deltaic rives among which the Lena River contributes about two thirds of the inflowing freshwater volume. The area of this freshened surface layer is much greater than the area of the freshened surface layer in the neighboring Kara Sea, while the total annual freshwater discharge to the Laptev and East-Siberian seas is 1.5 times less than to the Kara Sea (mainly from the estuaries of the Ob and Yenisei rivers). This feature is caused by differences in morphology of the estuaries and deltas. Shallow and narrow channels of the Lena Delta are limitedly affected by sea water. As a result, undiluted Lena discharge inflows to sea from multiple channels and forms relatively shallow plume, as compared to the Ob-Yenisei plumes which mix with subjacent saline sea water in deep and wide estuaries. Therefore, during its primary formation, the Lena plume has a smaller vertical scale but spreads over a larger area of the sea than the Ob-Yenisei plume.

Moreover, the area and position of the Lena plume have large inter-annual variability governed by local wind forcing, while the Ob-Yenisei plume has almost the same area and position in different years. The wind impulse limitedly penetrates below the boundary between the river plume and the underlying sea because of a sharp density gradient. As a result, the wind energy is concentrated in a relatively thin surface layer, and the intensity of the wind induced transport of the river plume negatively depends on its thickness. In particular, the Lena plume is much more susceptible to the impact of wind than the Ob Yenisei plume. Finally, the Lena plume forms a buoyancy and wind driven alongshore eastward flow, which is propagating towards the Bering Strait during ice-free periods and transports large volume of freshwater discharge. The Ob-Yenisei plume, on the opposite, does not form a stable eastward current during ice free-periods, albeit it occurs under sea ice in winter and spring.