Lake Evaporation On the Arctic Coastal Plain of Alaska: Results From an Energy Balance Study of a Thermokarst Lake Near Barrow, Alaska
Abstract
Thermokarst lakes are a prominent feature of the landscape on the Arctic Coastal Plain of northern Alaska. Otherwise known as “thaw lakes,” these shallow, water-filled depressions form in subsiding tundra in response to thawing permafrost. Occasionally, these lakes will drain and refill, sometimes undergoing numerous life cycles, and eventually leaving the landscape dotted with lakes and former lake basins. Understanding the dynamics of this unique, lake-rich landscape requires an assessment of the lakes’ water and energy balance, as well as an understanding of lake connectivity to the regional climate and climate variability. Given the ongoing, rapid climate change in the Arctic region, it is particularly important that we begin to address these issues so that the effects of climate change on this vast water resource can be assessed. In this study, we present results from an ongoing project to intensively measure the energy and water balance of a variety of thaw lakes on Alaska’s Arctic Coastal Plain. As part of this study, we have deployed a meteorological buoy on Freshwater Lake (in Barrow, Alaska) for the past two years (July 2008 to present). The weather station provides measurements of incoming and outgoing shortwave and longwave radiation, as well as air temperature, humidity, wind speed, rainfall, barometric pressure, and water temperature throughout the water column. The buoy is left to freeze in during winter to continue data collection during the freeze-up, ice-covered, and thaw periods. Additionally, temperature probes have been installed in the lake sediments to monitor heat fluxes into and out of the lake bottom. An analysis of the lake’s energy budget during the summer reveals that heat input to the lake is dominated by incoming solar radiation. This is primarily offset by latent and sensible cooling, as the region is relatively cold and windy throughout the summer. Net longwave radiation and sediment heat fluxes provide only moderate cooling of the lake during the ice-free period. It was also found that mass transfer-derived lake evaporation rates compare very closely with those of the energy balance. This is encouraging, as it suggests that accurate modeling and predicting of lake evaporation rates in thaw lakes is feasible simply through estimates of temperature, humidity, and wind speed. Finally, we provide an analysis of the wintertime energy balance for 2008/09, as well as an assessment of the interannual variability in lake evaporation between the two summer field seasons.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.H51C0778H
- Keywords:
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- 1814 HYDROLOGY / Energy budgets;
- 1833 HYDROLOGY / Hydroclimatology;
- 1845 HYDROLOGY / Limnology;
- 1876 HYDROLOGY / Water budgets