Analytic representation of the active layer thickness field, Kuparuk RiverBasin, Alaska

The initial response of permafrost to global warming could be an increase i n active-layer thickness. Given that such changes could have severe consequ ences for human infrastructure and ecosystem stability, it is important to obtain information about spatial variations of the active layer correspondi ng to current climatic conditions, and to determine the magnitude of possib le near-surface permafrost degradation associated with climatic change. Sim ple analytical solutions for frost and thaw penetration depth have long bee n available, but were used primarily for practical applications at point lo cations in cold-region engineering. One of these methods, developed at Mosc ow State University by Kudryavtsev and co-workers, was used to develop a sp atially distributed analytic model that estimates the maximum annual depth of thaw. Kudryavtsev's procedures account for the effects of snow cover, ve getation, soil moisture, thermal properties, and regional climate, and prov ide estimates of surface temperature and active-layer thickness. GIS techni ques were used to incorporate climate records, digital cartographic product s, and field data into a spatially distributed estimate of active-layer thi ckness. Procedures were applied over a rectangular 22 300 km(2) area in nor th-central Alaska containing complex patterns of topography, vegetation, an d soils. Validation procedures indicate that the Kudrayavtsev solution, ada pted for spatial applications, yields accuracy and spatial resolution compa rable to an existing semi-empirical method. The simplicity and low data req uirements of the Kudryavtsev solution make it readily adaptable to differen t geographic scales and areas. The method has potential applications in cli mate-change studies. (C) 1999 Elsevier Science B.V. All rights reserved.