THE N-FACTOR AS A TOOL IN GEOCRYOLOGICAL MAPPING: SEASONAL THAW IN THE KUPARUK RIVER BASIN,ALASKA |
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| Authors: | A E Klene F E Nelson N I Shiklomanov |
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| Institution: | Department of Geography and Center for Climatic Research , University of Delaware , Newark, Delaware 19716 |
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| Abstract: | Although maps of active-layer thickness have useful roles in geocryology, polar ecology, and hydrology, a lack of geographically distributed data at appropriate scales has prevented their widespread implementation. The n-factor (ratio of temperature at the soil surface to that in the air) has considerable potential as a tool for mapping active-layer thickness and other geocryological parameters by providing refinements to relatively simple analytic solutions for the depth of thaw. Although temperature data from the soil surface under representative land-cover units have rarely been collected historically, recent advancements in data-logger technology allow the variability of soil-surface temperature regimes to be assessed inexpensively over small temporal and spatial intervals. Temperature data collected in the air at 2 m height and at the soil surface within 10 representative land-cover units in the Kuparuk River region of north-central Alaska were used to compute seasonal n-factor values for specific vegetation-soil associations. The resulting values were used with degree-day sums, a digital elevation model, and a digital map of vegetation to compute a modified Stefan estimate of thaw depth over a 26,278 km2 area. Comparisons between maps based on the n-factor and an empirical, data-intensive method show similar performance. Given sufficient ancillary data, the n-factor provides a useful tool for mapping active-layer thickness over large areas without intensive in situ data collection. Key words: Alaska, permafrost, active-layer thickness, frozen ground, mapping, temperature.] |
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| Keywords: | vegetation index precipitation Granger causality Sahel climate agricultural land use |
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