Modeling biogeochemical processes in a freshwater lake during the spring thermal bar

Abstract

This article describes a coupled physical–biological model for reproducing the ecological processes in a freshwater lake during the evolution of the thermal bar, a phenomenon of sinking of maximum density waters in a narrow zone. The biological part of the model includes 10 prognostic variables: nitrate, phosphate, ammonium, chlorophyll a, phytoplankton, zooplankton, and nitrate and phosphate detritus of small and large sizes. The results of modeling of hydrodynamic processes in Barguzin Bay of Lake Baikal using meteorological data for June 2019 demonstrate a short-term period of the thermal bar existence. The analysis of spatial distributions of biochemical variables of the model showed that the thermal bar acts as a natural barrier limiting the transfer of phosphates and plankton to the open lake.