Effects of climate on the active layer and permafrost on the north slope of Alaska, U.S.A.

T. Zhang, T. E. Osterkamp, K. Stamnes

Research output: Contribution to journalArticlepeer-review

160 Scopus citations

Abstract

Thermal regimes of the active layer and permafrost and their relations to the present-day climatic conditions on the north slope of Alaska, U.S.A. were investigated by using data collected over six years and by numerical modelling. The thickness of the active layer increases from the Arctic coast to the foothills of the Brooks Range and is directly proportional to summer air temperatures and thawing index. Within about 120 km from the Arctic coast, mean annual air temperature for the period from 1987 through 1992 was nearly constant at about -12.4 ± 0.4°C, while the mean annual ground surface and permafrost surface temperatures increased more than 4°C. Variations in the length of thaw season and thawing index are the major factors which influence permafrost temperatures during the summer. Interactions of wind, microrelief, vegetation and seasonal snow cover and variations of physical (such as density and structure) and thermal properties of snow are the major factors affecting permafrost temperatures during the winter. The insulating effect of the seasonal snow cover could be either positive or negative on a daily basis depending upon the synoptic weather processes and on a monthly basis depending upon the time of year. On an annual basis, seasonal snow cover could increase the mean annual ground surface temperature by 2 to 7°C. Over a decade, snow cover also shows a strong effect on permafrost temperatures. Modelling results show that the depth hoar fraction of the seasonal snow cover varies from about 0.31 along the coast to about 0.57 inland. Higher permafrost temperatures along the foothills of the Brooks Range are the results of warm winters due to the impact of less strong atmospheric temperature inversion.

Original languageEnglish
Pages (from-to)45-67
Number of pages23
JournalPermafrost and Periglacial Processes
Volume8
Issue number1
DOIs
StatePublished - 1997

Keywords

  • Active layer
  • Alaska
  • Climate
  • Modelling
  • Permafrost

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