A FIELD SURVEY OF LATE-SUMMER DEPTHS TO FROZEN GROUND AT 2 STUDY AREAS NEAR MAYO, YUKON-TERRITORY, CANADA

A field survey of late-summer depths to frozen ground within 1.5 m of ground surface was performed in July and August of 1994, in support of the Cryospheric System programme of the Earth Observing System. This project's stratified sampling technique was devised to be a simple and efficient means to sample a very large number of sites over two areas of interest, within a relatively short period. The successful complet ion of the 1994 field season resulted in the compilation of a large an d representative. dataset of depths to frozen ground near Mayo, Yukon Territory. The survey suggests that most late-summer depths to frozen ground cluster within a narrow depth range in the main study area, whi le a much smaller proportion of this study area's dataset extends deep er to the 1.5 m depth limit of this study. Furthermore, the results of the survey suggest that considerable differences can exist between cl osely spaced study areas with regard to predominant depths to frozen g round, as well as relations between surface variables and depths to fr ozen ground. This implies that computer-based models designed to map a ctive layer thicknesses through correlation with landcover and topogra phic imagery must be supported by field measurements made in all areas being mapped. The extrapolation of correlations measured between acti ve layer conditions and surface variables from one study area to an un surveyed study area cannot be assumed to be valid. The mapping of acti ve layer thickness over large regions (e.g. central Yukon) will theref ore require a considerable field effort if reliable correlative mappin g products are to be generated.