Temporal changes in moisture content of the active layer and near-surface permafrost at Barrow, Alaska, USA: 1962-1994

Cores were extracted from frozen ground along a transect near Barrow, Alaska in spring 1963, and resampled within 0.5 m of the original boreholes in November 1993 and again in May 1994. Cores were cut into 5-cm segments and moisture content determined using standard techniques. The near-surface permafrost appears, on average, to have undergone ice enrichment from 1963 to 1993 since the mean volumetric water increased from about 57 to 62% over this 30-yr period. Comparison of the 1993 and 1994 data sets indicate slight depletion (3%) of moisture during winter in the paired samples extracted from the permafrost and the active layer. Although the results indicate winter desiccation and long-term (30-yr) net moisture gain in the upper permafrost, some evidence suggests that these patterns reflect the effects of spatial heterogeneity across short (<0.5 m) lateral distances.