Ground temperature variability on a glacier foreland, Storbreen, Jotunheimen, Norway

Abstract

Two-years of ground temperatures (10 cm and 50 cm depths) from the foreland of Storbreen in the Jotunheimen Mountains of Norway demonstrate that seasonal and annual ground temperature differences induced by microtopographic position at a constant elevation are comparable to differences stemming from ∼ 100 m to ∼ 300 m in elevation. Between ∼ 1460 m a.s.l. and ∼ 1150 m a.s.l., mean annual lapse rates calculated for soil depths of 10 cm were≤0.8°C per100m beneath tundra, moraine crests, and moraine proximal base positions, each of which was calculated independently. Seasonal lapse rates were often larger,≥1.0°C per 100m in both summer and winter. The calculated ground temperature lapse rates compare favorably with those already reported in the literature for the region. Categorical data in the form of Thawed, Freeze-Thaw, Isothermal, and Frozen Days also showed considerable variability by elevation and microtopographic position. Variability in growing conditions was examined by calculating Thawing Degree Days and Growing Degree Days. These values sometimes, but not always, mimic ground temperature patterns. Although no wintertime field observations are available, the depth and duration of seasonal snow cover appears to be the primary source of variability.

Keywords:

• Elevation
• microtopography
• Norway
• soil temperature regimes

Acknowledgements

Field research for this paper was funded by National Geographic Society Grant #6237-98. Our earlier research, as well as the present work, has benefited from the generous logistical and scientific support of John A. Matthews (University of Swansea). All of the air climate and snowfall data were provided by Ketil Isaksen of the Norwegian Meteorological Office. Hugh M. French reviewed an earlier version of this paper, and Ketil Isaksen and an anonymous reviewer the present version. We offer sincere thanks to all of the aforementioned.

Notes

1. This is Jotunheimen Research Expeditions Contribution No. 164.