Special issue  

Properties of seasonally ice covered lakes aren't currently sufficiently included in global climate models. To fill this gap, this study evaluates three models that could be used to quantify the amount of heat that moves from and into the lake by the air above it and through evaporation of the ice cover. The results show that difficulties in measuring the surface temperature of ice introduce errors and that a simple model was better at predicting the transport of heat than the complex models.

The time when lakes freeze varies considerably from year to year. A common way to predict it is to use negative degree days, i.e. the sum of air temperatures below 0 °C, a proxy for the heat lost to the atmosphere. Here we show that this is insufficient because the mixing of the surface layer induced by wind tends to delay the formation of ice. To do so, we developed a minimal model based on a simplified energy balance, which can be used both for large-scale analyses and short-term predictions.

We present the first evaluations of evaporation over a glacial lake located East Antarctica. We evaluated evaporation over the lake ice free surface using various methods, and estimated the errors inherent to them. The evaporation was evaluated on the basis of data collected during a field experiment. We conclude that evaporation is a major term of the water balance of glacial lakes, and our results demonstrated the need to account the glacial lakes in regional weather and climate prediction.

Leaching of dissolved organic carbon (DOC) from soils to the river network is an important component of the land carbon (C) budget but its spatio-temporal variation is not yet fully constrained. We use a land surface model to simulate at the European scale the present-day land C budget including leaching of DOC from the soil. We found an average leaching of 14.3 TgC/yr (0.6 % of the terrestrial net primary production) with seasonal variations. We determine runoff and temperature as main drivers.

The effect of inland waters on the climate is commonly parameterized as a function of surface water temperature that is estimated by 1D models that run coupled with climate models. These models often neglect advection due to inflows. Analyzing the trade-off between the complexity and requirements of different modeling approaches and the accuracy of their results, this study highlights the need to accurately model reservoir dynamics and selects an efficient way of doing so.

Wind blowing over the ocean creates waves, which by increasing the level of turbulence, promote gas exchange at the air-water interface. In this study we measured for the first time enhanced gas exchanges by wind-induced waves at the surface of a large lake. We adapted an ocean-based model to account for surface waves on gas exchange in lakes. We finally show that intense wind events with surface waves contribute disproportionately to the annual CO₂ gas flux in a large lake.

An operational lake forecast system was developed and tested for a large lake. The system predicted storm-surge and up-/down-welling events that are important for flood water and drinking water/fishery management. This study provides an example of the successful development of an operational forecast system, driven by open-access meteorological forecast, validated by online real-time observations, that can be adapted to simulate aquatic systems as required for management and public safety.