Thermokarst Lakes on the Arctic Coastal Plain of Alaska: Spatial and Temporal Variability in Summer Water Temperature

Abstract

In summer 2010, water temperature profile measurements were made in 12 thermokarst lakes along a 150‐km long north–south transect across the Arctic Coastal Plain of northern Alaska. In shallow lakes, gradual warming of the water column to 1–4°C begins at the lake bed during decay of the ice cover in spring. Rapid warming follows ice‐off, with water temperature responding synchronously to synoptic weather variations across the area. Regionally, ice‐off occurs 2–4 weeks later on lakes near the coast. Inland lakes are warmer (13°C) in mid‐summer than those near the coast (7°C), reflecting the regional climate gradient and the maritime effect. All lakes are well mixed and largely isothermal, with some thermal stratification (< 2°C) occurring during calm, sunny periods in deeper lakes. In deep (6–9 m) lake‐bed depressions that are likely ice‐wedge troughs, water cools by conduction to the colder sediments below, while concurrent warming occurs in the upper water column. A spatially dense sample of near‐surface temperature measurements was collected from one lake over a short period and shows warmer (2–3°C) temperatures on the upwind, sheltered end of the lake. This study demonstrates that climatic gradients, meteorological conditions and basin characteristics impact lake temperature dynamics. Copyright © 2012 John Wiley & Sons, Ltd.

Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

“…For example, in northern Québec, in a region extending from continuous to discontinuous and sporadic permafrost, maximum lake depths range from 1 to 3.5 m (Breton et al, 2009;Laurion et al, 2010;Bouchard et al, 2011;Crevecoeur et al, 2015). Similarly, lake depths range from 0.5 to 1.5 m on a discontinuous permafrost tundra in western Siberia , from 0.4 to 2.6 m in an area of continuous permafrost in northern Alaska (Arp et al, 2011), and from 1 to 3.5 m in continuous permafrost of the Arctic Coastal Plain (Hinkel et al, 2012). However, thermokarst lakes approaching 10 m depth can be found in interior Alaska and lakes deeper than 10 m can be found on the Seward Peninsula, Alaska (Hopkins, 1949) and northeast Siberia (Walter Anthony and Anthony, 2013); thermokarst lakes as deep as 22 m exist on the Yukon Coastal Plain of north-western Canada (West and Plug, 2008).…”

“…Many thermokarst lakes are likely to be cold polymictic, undergoing stratification events that become established and then break down over diurnal, or several day, cycles (Alaska, Hinkel et al, 2012;Canadian sub-Arctic, Deshpande et al, 2015). The increased use of high resolution, automated temperature loggers is likely to yield new insights into these short term stratification and mixing dynamics, even in those lakes currently considered to be well-mixed in summer.…”

Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland

“…Currently, in the Arctic, small lakes (surface area < 10 km 2 ) are abundant (Downing, 2010;Downing et al, 2006) and emit substantially more CH 4 per unit area than larger lakes (Bastviken et al, 2004;Cole et al, 2007;Juutinen et al, 2009;Wik et al, 2016), and seasonal variability in CH 4 emissions are influenced by energy input and organic carbon availability (Tan et al, 2015). However, climate change will lead to variations in heat balance, temperature profiles, and vertical mixing in lakes (Jankowski et al, 2006;MacIntyre et al, 2009;Hinkel et al, 2012;Butcher et al, 2015), causing many variations to both lake structure (Livingstone 2003;Coats et al, 2006) and CH 4 dynamics. Microbial production of CH 4 by methanogens is dependent upon anoxia, temperature, and the amount and quality of organic carbon substrates (Liikanen et al, 2003;Kankaala et al, 2006;Duc et al, 2010;Borrel et al, 2011).…”

Spatio-Temporal Analysis of Gyres in Oriented Lakes on the Arctic Coastal Plain of Northern Alaska Based on Remotely Sensed Images

“…The horizontal and vertical mixing ability of wind-driven gyres in part contributes to the largely isothermal lakes during the summer as documented by Hinkel et al, [32]. Surdu et al, [8] have found a later ice onset by 5.9 days, a significant advancement of ice melt by 17.7 to 18.6 days and a decrease in the ice season by 23.6 to 24.8 days in the lakes near Barrow, Alaska from 1950 to 2011 using model simulations.…”

“…Figure 3 shows the dominant bimodal (east and west) summer wind in Barrow, Alaska from 1 June to 30 September 2013. Waves and currents in these lakes are most likely to be driven by summer winds as the lakes are small and shallow and lake water largely isothermal during the ice-free season [32]. The mean depth of more than 20 lakes on the western OCP and ICP measured by Hinkel et al [33] ranges from 1-2 m with the maximum depth rarely over 5 m. Lakes on the OCP near Barrow have flat bottoms and no well-developed littoral shelves while lakes on the ICP have varying bottom topography and prominent littoral shelves [33].…”