Abstract
Based on the results of numerical calculations on a three-dimensional hydrodynamic model, the response of a shallow lake to wind action during the open water period was studied. The estimate of the atmospheric impact on the lake is based on ERA5 re-analysis data. The fields of currents and water temperature are analyzed for the period from May to December with alternating weekly intervals of calm and wind action at a constant speed of 3 m/s (the first and third weeks of the month are west and east winds, respectively, the second and fourth are calm). The model calculations showed that the spring-summer heating stage in the lake lasted from early May to mid-August. The periods of strong and weak stratification alternated against the background of increased wind load and changes in air temperature. From mid-August onwards the lake cooled down in a state of homothermia. According to the model calculations, stable circulation is formed in the lake already on the first day of the wind. On the second and third days, the current velocities increased reaching a maximum of 0.05–0.15 m/s, and changed very little during the next 4–7 days of wind. Under calm conditions, the currents decayed within 2–3 days. With homothermy, wind circulation engaged the entire water column, with currents greater than during stratification. During periods of stratification under the influence of wind, a surface mixed layer was formed, the thickness of which reached 3–4 m by the seventh day of the wind load. The velocities of currents in the mixed layer were noticeably higher than under the thermocline. In the first days of the calm, stratification began to recover. The alternation of periods of wind and calm at the stage of spring-summer heating of the lake contributed to the accumulation of heat in the surface layers of the water column and its transfer to the hypolimnion, and then to the sediments. Simulated and observed data on water temperature and current velocities in the lake showed good agreement.
Highlights
По результатам численных расчетов на трехмерной гидродинамической модели изучена реакция мелководного озера на ветровую нагрузку в период открытой воды
The estimate of the atmospheric impact on the lake is based on ERA5 re-analysis data
The fields of currents and water temperature are analyzed for the period from May to December with alternating weekly intervals of calm and wind action at a constant speed of 3 m/s
Summary
По результатам численных расчетов на трехмерной гидродинамической модели изучена реакция мелководного озера на ветровую нагрузку в период открытой воды. The alternation of periods of wind and calm at the stage of spring-summer heating of the lake contributed to the accumulation of heat in the surface layers of the water column and its transfer to the hypolimnion, and to the sediments. Поскольку модель ранее была успешно верифицирована по данным наблюдений на глубоководных и мелководных акваториях других озер [см., например: Зверев и др., 2015; Мотовилов и др., 2020] с использованием реанализа NCEP/NCAR, авторы полагают, что выполненная замена реанализа способна только улучшить качество расчетов для озера Вендюрского в период открытой воды.
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