Predicting thermal responses of an Arctic lake to whole-lake warming manipulation at Toolik Field Station July 1, 2018 to August 31, 2018

We investigated how lake thermal processes responded to whole-lake warming manipulation for in an Arctic Alaskan lake through observations and numerical modeling. The warming manipulation was conducted by artificially heating the epilimnion of the lake as a proxy for climate warming. We performed numerical modeling and used an improved lake scheme based on the Community Land Model (CLM). We simulated a control run (CTL) without warming and a warming manipulation simulation (WARM). Results indicated that the WARM simulation accurately captured the observed lake temperature profiles where water stratification was extended in time, and water stability was strengthened. Two additional sensitivity tests with different warming onset dates and of the same warming durations showed that earlier onsets of warming are predicted to make the lake water column more stable and less easily mixed relative to a later onset of warming. The results of this study provide a more complete understanding of lake thermal processes in Arctic freshwater lake systems and of how they will respond to predicteda future warming world.