Spatial and temporal variation in thaw depth in Siberian tundra near Tiksi

Siberian tundra is characterised by permafrost overlaid with an active layer. The spatial and temporal variation in the thaw depth in the active layer may play an important role in biological and hydrological processes. In this study, we carried out field investigations of flat tundra and a hillslope in a watershed near Tiksi, Siberia, at various scales, from 1997 to 2000. The ground started to thaw in early June and refroze in mid September. The progress in the ground thaw was proportional to the square root of the thawing index. The maximum thaw, which was observed at the end of August, ranged from 1.2 to 0.2 m and averaged 0.4 m. The spatial variation was analysed using a variogram method. The ground thaw had a fractal dimension ( 1.8) at each scale. While there was no anisotropy in the thaw depth in the flat area, the thaw depth on the hillslope periodically fluctuated perpendicular to direction of maximum slope. Permafrost, Phillips, Springman & Arenson (eds) © 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 582 7