Thaw lake expansion in a two‐dimensional coupled model of heat transfer, thaw subsidence, and mass movement

Abstract

[1] Thaw lakes, widespread in permafrost lowlands, expand their basins by conduction of heat from warm lake water into adjacent permafrost, subsidence of icy permafrost on thawing, and movement of thawed sediment from lake margins into basins by diffusive and advective mass wasting. We describe a cross-sectional numerical model with thermal processes and mass wasting. To test the model and provide an initial investigation of its utility, the model is driven using historical daily temperatures and permafrost conditions for the northern Seward Peninsula, Alaska (NSP; thick syngenetic ice, mean annual air temperature (MAAT) À6°C) and Yukon coastal plain (YCP; thin epigenetic ice, MAAT À10°C). In the model, lakes develop dynamic equilibrium profiles that are independent of initial morphology. These profiles migrate outward episodically and match the morphology of profiles from lakes that were measured at each site. Modeled NSP lakes expand more rapidly than YCP lakes (0.26 versus 0.10 m a À1 ) under respective modern climates. When identical climates are imposed, NSP lakes still grow more rapidly because their deeper basins and steeper bathymetric slopes move thawed insulating sediment away from the lake margin. In sensitivity tests, an increase of 3°C in MAAT causes 2.5Â (NSP) and 1.6Â (YCP) faster expansion of lakes. An 8°C decrease essentially halts expansion for both sites, consistent with paleostudies which attribute basins to postglacial warming. In the model, basins expand monotonically but lakes do not. The 1s interannual variability of lake expansion is 0.51 (NSP) and 0.44 m a À1 (YCP), with single year rates of up to ±8 m occurring because of instabilities from thermal/mass movement coupling even under a stationary climate. This variability is likely a minimum estimate, compared to natural variability, and suggests that long measurement time series, of basins not lake surfaces, would best detect thermokarst acceleration resulting from a climate change.Citation: Plug, L. J., and J. J. West (2009), Thaw lake expansion in a two-dimensional coupled model of heat transfer, thaw subsidence, and mass movement,

Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia

“…Furthermore, small water bodies and lakes can strongly modify the ground thermal regime both in the underlying ground and in the surrounding land areas Langer et al, 2015), so the model results are questionable in areas with a high fraction of open water areas (Muster et al, 2012). While more sophisticated model schemes (Plug and West, 2009;Westermann et al, 2016) can simulate the ground thermal regime of such features, a spatially distributed application is challenging: in general, higher-complexity models require additional input data and model parameter sets (e.g., precipitation for a water balance model, Endrizzi et al, 2014), for which the spatial and temporal distributions are poorly known. Furthermore, the model sensitivity may vary in space depending on the interplay of different model parameters and input data (Gubler et al, 2013), which makes it harder to judge the uncertainty of model results.…”

“…Spatially distributed permafrost modeling was, for example, demonstrated by Zhang et al (2013) and Westermann et al (2013), forced by interpolations of meteorological measurements, or by Jafarov et al (2012) and Fiddes et al (2015) by downscaled atmospheric model data. Remote-sensing data sets have been extensively used to indirectly infer the ground thermal state through surface observations, e.g., occurrence and evolution of thermokarst features (e.g., Jones et al, 2011), vegetation types characteristic for permafrost (Panda et al, 2014) or change detection of spectral indices (Nitze and Grosse, 2016). As permafrost is a subsurface temperature phenomenon, it is not possible to observe it directly from satellite-borne sensors.…”

Eos, Transactions, American Geophysical Union Volume 91, Number 26, 29 June 2010

“…Also promising are recent efforts to consider enhanced melting of massive ground ice by flowing water [Marsh and Neumann, 2001]. Other efforts to estimate the loss of soil volume due to ground ice melting and the resulting failure of lake shores [Plug and West, 2009] are also yielding interesting results. Such efforts offer possible ways that feedbacks associated with lake expansion or drainage can be incorporated into larger models.…”

Freeze/thaw processes in complex permafrost landscapes of northern Siberia simulated using the TEM ecosystem model: impact of thermokarst ponds and lakes

“…11), but since the DOS-TEM is a one-dimensional model it is unable to simulate lateral heat exchange. A two-or three-dimensional model would be better able to simulate the thermal processes in complex Arctic tundra landscapes (e.g., Ling and Zhang, 2003;Plug and West, 2009;van Huissteden et al, 2011;Kessler et al, 2012), but such models are difficult to apply over large regions.…”

“…Unfortunately, however, such information is not readily available at present. A new technology known as surface nuclear magnetic resonance has recently been used over thermokarst lakes to measure the underlying talik thickness (Parsekian et al, 2013) and promises to provide useful information on talik that can be used to improve modeling in future studies.…”