References

The Cryosphere

1994-0424

Copernicus Publications

Göttingen, Germany

10.5194/tc-8-167-2014

Response of ice cover on shallow lakes of the North Slope of Alaska to contemporary climate conditions (1950–2011): radar remote-sensing and numerical modeling data analysis

Surdu

C. M.

¹ Duguay

C. R.

https://orcid.org/0000-0002-1044-5850

¹ Brown

L. C.

² Fernández Prieto

Department of Geography & Environmental Management and Interdisciplinary Centre on Climate Change (IC<sup>3</sup>), University of Waterloo, Waterloo, Canada

Climate Research Division, Environment Canada, Toronto, Canada

EO Science, Applications and Future Technologies Department, European Space Agency (ESA), ESA-ESRIN, Frascati, Italy

30 01 2014

8 1 167 180

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://tc.copernicus.org/articles/8/167/2014/tc-8-167-2014.html

The full text article is available as a PDF file from https://tc.copernicus.org/articles/8/167/2014/tc-8-167-2014.pdf

Air temperature and winter precipitation changes over the last five decades have impacted the timing, duration, and thickness of the ice cover on Arctic lakes as shown by recent studies. In the case of shallow tundra lakes, many of which are less than 3 m deep, warmer climate conditions could result in thinner ice covers and consequently, in a smaller fraction of lakes freezing to their bed in winter. However, these changes have not yet been comprehensively documented. The analysis of a 20 yr time series of European remote sensing satellite ERS-1/2 synthetic aperture radar (SAR) data and a numerical lake ice model were employed to determine the response of ice cover (thickness, freezing to the bed, and phenology) on shallow lakes of the North Slope of Alaska (NSA) to climate conditions over the last six decades. Given the large area covered by these lakes, changes in the regional climate and weather are related to regime shifts in the ice cover of the lakes. Analysis of available SAR data from 1991 to 2011, from a sub-region of the NSA near Barrow, shows a reduction in the fraction of lakes that freeze to the bed in late winter. This finding is in good agreement with the decrease in ice thickness simulated with the Canadian Lake Ice Model (CLIMo), a lower fraction of lakes frozen to the bed corresponding to a thinner ice cover. Observed changes of the ice cover show a trend toward increasing floating ice fractions from 1991 to 2011, with the greatest change occurring in April, when the grounded ice fraction declined by 22% (α = 0.01). Model results indicate a trend toward thinner ice covers by 18–22 cm (no-snow and 53% snow depth scenarios, α = 0.01) during the 1991–2011 period and by 21–38 cm (α = 0.001) from 1950 to 2011. The longer trend analysis (1950–2011) also shows a decrease in the ice cover duration by ~24 days consequent to later freeze-up dates by 5.9 days (α = 0.1) and earlier break-up dates by 17.7–18.6 days (α = 0.001).

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