Establishing long‐term permafrost observatories for active‐layer and permafrost investigations in Alaska: 1977–2002

Twenty‐five years ago a programme was initiated to establish a statewide system of permafrost observatories that included boreholes drilled for the express purpose of investigating the effects of changes in climate on continuous and discontinuous permafrost. A total of 22 permafrost observatories have been established with boreholes 15 to 80 m in depth. These sites are primarily along a north‐south transect of Alaska paralleling the Alyeska oil pipeline from Prudhoe Bay to Glennallen and are visited and serviced annually. There are seven additional borehole sites with holes 15 to 80 m in depth that are visited occasionally. The sites are in undisturbed locations with nearly uniform conditions in a wide variety of environmental settings except for a few, purposefully placed in disturbed areas (e.g. farm field, burn, etc.). Proximity to meteorological stations with long weather records has allowed reconstruction of past active‐layer and permafrost conditions using calibrated site‐specific models. The sites have been used to document a recent warming trend in permafrost and active‐layer temperatures and to investigate the characteristics of the permafrost and active layer and processes that occur in them. Recommendations are made for establishing future observatories. Copyright © 2003 John Wiley & Sons, Ltd.