0000000000716920
AUTHOR
Timo Huttula
Applicability and consequences of the integration of alternative models for CO2 transfer velocity into a process-based lake model
Freshwater lakes are important in carbon cycling, especially in the boreal zone where many lakes are supersaturated with the greenhouse gas carbon dioxide (CO2) and emit it to the atmosphere, thus ventilating carbon originally fixed by the terrestrial system. The exchange of CO2 between water and the atmosphere is commonly estimated using simple wind-based parameterizations or models of gas transfer velocity (k). More complex surface renewal models, however, have been shown to yield more correct estimates of k in comparison with direct CO2 flux measurements. We incorporated four gas exchange models with different complexity into a vertical process-based physico-biochemical lake model, MyLak…
Lake Load Response (LLR) – mallityökalu vesialueiden hoidon suunnittelun apuvälineenä
For eutrophic lakes, achieving good water quality usually requires a reduction in external loading. The Lake Load Response (LLR) tool, based on the LakeState (LS) model, can be used to predict the necessary loading reduction, which can be utilized when making decisions on the management of the lake. The best predictions are made when the input values of the incoming loading, water outflow and in-lake total phosphorus, total nitrogen and chlorophyll a concentrations are as accurate as possible. Accurate loading data is often hard to collect because of the lack of resources for observations. However, LLR-runs made for the lake Lehesjärvi-Vähäjärvi in Jyväskylä showed that examining the needed…
Unicorn-Open science for assessing environmental state, human health and regional economy
Open data and models are becoming increasingly available, but there are not yet good methods and platforms to turn those into systematic evidence-based decision support. Unicorn will produce such an environment based on existing theoretical and practical knowledge about decision support and models. This con sortium possesses the necessary models, data, and skills to set up an environment and demonstrate its func tionality and usefulness with several case studies related to the environmental issues, human health, and economy. The Unicorn environment will be built in a generic and systematic way so that it could even be come an international standard for evidence-based decision support. Devel…
Modelling circulation in an ice-covered lake
In deep ice-covered lakes with temperatures below 4 °C the heat flux from the bottom sediment results in a horizontal density gradient and a consequent flow along the bottom slope. Measurements in Lake Paajarvi, Finland, show a stable temperature field where a heat gain through the bottom and a heat loss through the ice nearly balance each other. The circulation is thermal with low velocities (less than 1.5 cm s -1 ). We used the 3D hydrodynamic Princeton Ocean Model as a tool to simulate the water circulation and the temperature distribution under the ice. The model forcing was based on field temperature measurements. The model simulations suggest that in midwinter the velocity field of th…
Applicability and consequences of the integration of alternative models for CO<sub>2</sub> transfer velocity into a process-based lake model
Abstract. Freshwater lakes are important in carbon cycling, especially in the boreal zone where many lakes are supersaturated with the greenhouse gas carbon dioxide (CO2) and emit it to the atmosphere, thus ventilating carbon originally fixed by the terrestrial system. The exchange of CO2 between water and the atmosphere is commonly estimated using simple wind-based parameterizations or models of gas transfer velocity (k). More complex surface renewal models, however, have been shown to yield more correct estimates of k in comparison with direct CO2 flux measurements. We incorporated four gas exchange models with different complexity into a vertical process-based physico-biochemical lake mo…