The n-factor as a tool in geocryological mapping: Seasonal thaw in the kuparuk river basin, alaska

N. I. Shiklomanov, A. E. Klene, F. E. Nelson

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


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.

Original languageEnglish
Pages (from-to)449-466
Number of pages18
JournalPhysical Geography
Issue number6
StatePublished - 2001


  • Active-layer thickness
  • Alaska
  • Frozen ground
  • Mapping
  • Permafrost
  • Temperature


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