Modification of Laptev sea freshened shelf waters based on isotope and salinity relations

Abstract

This paper is dedicated to the estimation of the river runoff contribution to the Arctic shelf waters, where freezing and melting of desalinated waters are intensively proceeding. A mixing-modification model is offered. The model takes into account the sea ice formation from desalinated waters on the shelf. The model was used to explain the data obtained from 63 and 69 cruises of the research vessel “Akademik Mstislav Keldysh” (2015 and 2017). Two sources of water masses — the Atlantic waters and the Lena river were established for the studied area of Laptev Sea. The waters in this zone are modified, i.e. they have a higher salinity than the one that corresponds to the two components mixing. The presence of modified waters generated at the Laptev Sea shelf is traced in the continental slope zone. Desalination in the continental slope zone reaches 15–27% and affects depths no more than 20 m, at more than 50 m depths it is practically disappeared. A mixing-modification model was proposed to calculate river water input in the modified waters. The data obtained for the Laptev Sea shelf were used to calculate the fraction of river waters according to both the proposed model and the conventional three-component mixing model of Ostlund and Hut, 1984. A comparison of the estimates obtained by both models has shown that the application of the three-component mixing model to modified waters leads to an overestimation of the river water contribution, which can reach 20%. Each sample of shelf waters can be processed using either a mixture-modification model or a three-component mixing model. To choose the appropriate model the special criterion is proposed. Using this criterion, the calculations of river water and melted ice contribution will be free from the unrealistic or negative values.