Abstract
ABSTRACTA 1-D ice cover model was developed to predict and constrain drivers of long-term ice thickness trends in chemically stratified lakes of Taylor Valley, Antarctica. The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column. The model successfully reproduced 16 a (between 1996 and 2012) of ice thickness changes for the west lobe of Lake Bonney (average ice thickness = 3.53 m) and Lake Fryxell (average ice thickness = 4.22 m). Long-term ice thickness trends require coupling with the thermal structure of the water column. The heat stored within the temperature maximum of lakes exceeding a liquid water column depth of 20 m can either impede or facilitate ice thickness change depending on the predominant climatic trend (cooling or warming). As such, shallow (<20 m deep water columns) perennially ice-covered lakes without deep temperature maxima are more sensitive indicators of climate change. The long-term ice thickness trends are a result of surface energy flux and heat flux from the deep temperature maximum in the water column, the latter of which results from absorbed solar radiation.
Highlights
Ice-covered lakes in the McMurdo Dry Valleys, Antarctica have long been studied as novel habitats for life
A thermodynamic model parameterized for ice cover of west lobe of Lake Bonney (WLB) was developed
The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column, coupled with two 1-D heat equations
Summary
Ice-covered lakes in the McMurdo Dry Valleys, Antarctica have long been studied as novel habitats for life. Between 1986 and 1999, the lake-ice thickness increased at a rate of 0.11 m a−1 in association with an annual air temperature decrease of 0.7°C (10 a)−1 (Doran and others, 2002b) This period of pronounced cooling was terminated by one of the warmest summers on record, resulting in a significant lake level rise (Barrett and others, 2008; Doran and others, 2008). Following this warm pulse, lakeice thicknesses have been decreasing since early- to mid2000 at rates between 0.07 and 0.18 m a−1 (unpublished data). We present results from a lake ice model that allowed us to differentiate between the influence of atmospheric processes (i.e. changes in climate) and the long-term heat storage in the water column on lake ice thickness
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