The influence of snow cover, air temperature, and groundwater flow on the active-layer thermal regime of Arctic hillslopes drained by water tracks

Rushlow, Caitlin R.; Sawyer, Audrey H.; Voss, Clifford I.; Godsey, Sarah E.

The influence of snow cover, air temperature, and groundwater flow on the active-layer thermal regime of Arctic hillslopes drained by water tracks | Influence de la couverture neigeuse, de la température de l’air et de l’écoulement des eaux souterraines sur le régime thermique de la couche active des versants de l’Arctique drainés par des chenaux La influencia de la cubierta de nieve, la temperatura del aire y el flujo de aguas subterráneas en el régimen térmico de la capa activa de las laderas del Ártico drenadas mediante vertientes de agua 冰雪覆盖、气温和地下水流动对水迹排水的北极山坡融冻层热状态的影响 A influência da cobertura de neve, temperatura do ar, e fluxo das águas subterrâneas no regime termal da camada ativa de encostas no Árticas drenadas por trilhas de água

2020

Rushlow, Caitlin R. | Sawyer, Audrey H. | Voss, Clifford I. | Godsey, Sarah E.

Permafrost in Arctic watersheds limits soil biological activity to a thin, seasonally thawed active layer that contributes water to streams. In many hillslopes, relatively wet drainage features called water tracks have distinct freeze-thaw patterns that affect groundwater flow and storage, and thus the export of heat and solutes to Arctic streams. This study uses groundwater flow and energy transport models to examine potential controls on the timing and duration of freeze–thaw conditions and the magnitude of temperature fluctuations within water tracks and their adjacent hillslopes. The simulated length of the active-layer thaw season varies by 1 month over the range of snow-cover and mean annual air-temperature scenarios simulated. The timing and duration of freezing is particularly sensitive to depth and duration of snow cover. Thus, the deeper snowpack covers that can accumulate in water tracks contribute to their more persistent thaw conditions and their ability to conduct groundwater downslope. A three-dimensional simulation shows that during the summer thaw season, the water track captures groundwater laterally from half way across the hillslope. The models presented here elucidate key mechanisms driving small-scale variation in the active-layer thermal regime of tundra hillslopes, which may be responsible for changes in drainage-network geometry and Arctic biogeochemical fluxes under a warming climate.

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