Effects of water clarity on lake stratification and lake-atmosphere heat exchange

Heiskanen, J.; IvanMammarella; Ojala, A.; Stepanenko, V.; Erkkilä, K.; Miettinen, H.; Sandström, H.; Eugster, W.; Leppäranta, M.; Järvinen, H.; Vesala, T.; Nordbo, A.

Авторы: Heiskanen Jouni, IvanMammarella, Anne Ojala, Victor Stepanenko, Kukka-Maaria Erkkilä, Heli Miettinen, Heidi Sandström, Werner Eugster, Matti Leppäranta, Heikki Järvinen, Timo Vesala, Annika Nordbo
Журнал: Journal of Geophysical Research
Том: 120
Год издания: 2015
Издательство: William Byrd Press for John Hopkins Press
Местоположение издательства: United States
Первая страница: 7412
Последняя страница: 7428
DOI: 10.1002/2014JD022938
Аннотация: Recent progress of including lake subroutines in numerical weather prediction (NWP) models has led to more accurate forecasts. In lake models, one essential parameter is water clarity, parameterized via the light extinction coefficient, Kd, for which a global constant value is usually used. We used direct eddy covariance fluxes and basic meteorological measurements coupled with lake water temperature and clarity measurements from a boreal lake to estimate the performance of two lake models, LAKE and FLake. These models represent two 1D modeling frameworks broadly used in NWP. The results show that the lake models are very sensitive to changes in Kd when it is lower than 0.5 m−1. The progress of thermal stratification depended strongly on Kd. In dark water simulations the mixed layer was shallower, longwave and turbulent heat losses higher and therefore the average water column temperatures lower than in clear water simulations. Thus, changes in water clarity can also affect the onset of ice cover. The more complex LAKE modeled the seasonal thermocline deepening whereas it remained virtually constant during summer in the FLake model. Both models overestimated the surface water temperatures by about 1°C and latent heat flux by >30%, but the variation in heat storage and sensible heat flux were adequately simulated. Our results suggest that, at least for humic lakes, a lake-specific, but not time-depending, constant value for Kd can be used and that a global mapping of Kd would be most beneficial in regions with relatively clear lakes, e.g. in lakes at high altitudes.
Добавил в систему: Степаненко Виктор Михайлович

	ИСТИНА	Войти в систему Регистрация
	ФНКЦ РР
	Главная Поиск Статистика О проекте Помощь

ИСТИНА

ФНКЦ РР

Effects of water clarity on lake stratification and lake-atmosphere heat exchangeстатья

Прикрепленные файлы