Study of Temperature Regime and Horizontal Heterogeneity in the Rybinsk Reservoir During the Open Water Period Using Three-Dimensional Mathematical Modeling

This paper presents a study of the thermal structure, circulation, and mixing processes in an inland water body by taking into account horizontal heterogeneity using a three-dimensional thermohydrodynamics model. The object of this study was the Rybinsk Reservoir, a large inland water body with complex morphology. Field measurement data and ERA5 reanalysis data, as well as a three-dimensional numerical model (which is a development by the authors of this article), were used in this research. The results of the numerical experiments show that three-dimensional numerical modeling, which explicitly takes into account the contribution of seiche oscillations, allows us to describe the temperature distribution in a water body with sufficient accuracy, and this plays a fundamental role in studies of inland water objects. The obtained results could be useful for a model representation of the biochemical processes occurring in lakes and reservoirs. Thus, for models of less spatial detail that are, for example, used to hlrepresent lakes in Earth system models, it is necessary to take into account seiches in the form of parameterizations.