Long-term active-layer trends: 20 years of Circumpolar Active Layer Monitoring (CALM) observations
Abstract
The uppermost layer of seasonal thawing above permafrost (the active layer) is an important regulator of energy and mass fluxes between the surface and the atmosphere in the cold regions. Active-layer monitoring is an important component of efforts to assess the effects of global change in permafrost environments. The Circumpolar Active Layer Monitoring (CALM) program, established in the early 1990s, is designed to observe temporal and spatial variability of the active layer, near-surface permafrost parameters, and their response to changes and variations in climatic conditions. The CALM network involves 14 participating countries and is comprised of more than 200 sites distributed throughout the Arctic, Antarctica, and in several mountain ranges of the mid-latitudes. Direct active-layer measurements are conducted on standard rectangular grids ranging from 10 x 10 m to 1 x 1 km. The locations of sites were selected to represent generalized surface and subsurface conditions characteristic of broad regions. The size of each grid reflects the level of local geographic variability. In this presentation we report the current status of the CALM program, provide an overview of the observational methodology, and report spatial and temporal trends in active-layer thickness for several Arctic regions over approximately 20 years.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMGC51I..04S
- Keywords:
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- 0702 CRYOSPHERE / Permafrost;
- 0706 CRYOSPHERE / Active layer;
- 1621 GLOBAL CHANGE / Cryospheric change