Abstract
Lake ice models are a vital tool for studying the response of ice-covered lakes to changing climates throughout the world. The Canadian Lake Ice Model (CLIMo) is a one-dimensional freshwater ice cover model that simulates Arctic and sub-Arctic lake ice cover well. Modelling ice cover in temperate regions has presented challenges due to the differences in ice composition between northern and temperate region lake ice. This study presents a comparison of measured and modelled ice regimes, with a focus on refining CLIMo for temperate regions. The study sites include two temperate region lakes (MacDonald Lake and Clear Lake, Central Ontario) and two High Arctic lakes (Resolute Lake and Small Lake, Nunavut) where climate and ice cover information have been recorded over three seasons. The ice cover simulations were validated with a combination of time lapse imagery, field measurements of snow depth, snow density, ice thickness and albedo data, and historical ice records from the Canadian Ice Database (for Resolute Lake). Simulations of High Arctic lake ice cover show good agreement with previous studies for ice-on and ice-off dates (MAE 6 to 8 days). Unadjusted simulations for the temperate region lakes show good ice-on timing, but an under-representation of ice thickness, and earlier complete ice-off timing (~3 to 5 weeks). Field measurements were used to adjust the albedo values used in CLIMo, which resulted in improvements to both simulated ice thickness (~3 cm MAE compared to manual measurements), and ice-off timing, within 0 to 7 days (2 days MAE) of observations. These findings suggest regionally specific measurements of albedo can improve the accuracy of lake ice simulations, which further our knowledge of the response of temperate and High Arctic lake ice regimes to climate conditions.
Highlights
The greatest spatial distribution of freshwater lakes is between 45 and 75◦N [1] with most of these lakes experiencing some level of ice cover throughout the year.Reported trends in lake ice cover have shown shifts towards shorter ice-covered seasons, with the rates of change depending on the time span examined, e.g., [2]
Long-term trends of Northern Hemisphere lakes project the number of lakes transitioning from annual ice cover to intermittent winter ice cover will increase exponentially with climate warming [3]
The initial ice cover that formed was subsequently broken-up by wave action, resulting in the final ice-on date occurring 14 days later in 2016 and 4 days later in 2017
Summary
The greatest spatial distribution of freshwater lakes is between 45 and 75◦N [1] with most of these lakes experiencing some level of ice cover throughout the year.Reported trends in lake ice cover have shown shifts towards shorter ice-covered seasons, with the rates of change depending on the time span examined, e.g., [2]. Regional water and energy balances will likely experience changes as a result of this decreasing ice cover; through changes to the exchange of moisture and gas fluxes (e.g., increased evaporation), as well as to ecosystems (e.g., earlier lake stratification, warmer summer surface temperatures and increased aquatic productivity) and socio-economic changes (e.g., reduced winter recreation and transportation) [2,4,5,6,7,8,9] These changes and their impacts vary spatially, due to latitudinal differences in ice types and how they respond to climate. With northern latitudes warming at a more rapid rate than southern latitudes [10], the latitudinal response of lake ice becomes even more pertinent
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