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Assessing vertical diffusion in a stratified lake using a three‐dimensional hydrodynamic model
Author(s) -
Dong Fei,
Mi Chenxi,
Hupfer Michael,
Lindenschmidt KarlErich,
Peng Wenqi,
Liu Xiaobo,
Rinke Karsten
Publication year - 2019
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.13653
Subject(s) - thermocline , stratification (seeds) , eddy diffusion , wind speed , thermal diffusivity , environmental science , diffusion , forcing (mathematics) , geology , turbulence , atmospheric sciences , hydrology (agriculture) , meteorology , climatology , physics , thermodynamics , oceanography , geotechnical engineering , seed dormancy , botany , germination , dormancy , biology
Vertical turbulent diffusivity (K z ), which can be estimated from water temperature, is a key factor in the evolution of water quality in lentic waters. In this study, we analysed the capability of a three‐dimensional hydrodynamic model (EFDC) to capture water temperature and vertical diffusivity in Lake Arendsee in the Northern German plain. Of particular interest to us is to evaluate the model performance for capturing the diffusion minimum within the metalimnion and analyse the response of the metalimnetic K z to meteorological forcing, namely changing wind speed and warming. The comparison confirmed that the calibrated model could reproduce both stratification dynamics and vertical diffusion profiles in the lake. The model was also shown to be able to capture the duration and vertical extent of the metalimnetic diffusion minimum. The scenario results illustrate that, compared to air temperature, wind velocity appeared to be the more influential meteorological variable on the vertical exchange within the metalimnion. While increasing wind velocities mostly affected the minimum values of K z in the metalimnion and thus led to intensified vertical exchange, the reduction of wind velocity mostly affected the depth of minimal K z , but not its absolute value.