Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
GTN-P Monitoring Network: Detection of a 3 K Permafrost Warming In Northern Alaska During the 1990's
Gary D. Clow1, Frank E. Urban2
1Earth Surface Dynamics, U.S. Geological Survey, Denver Federal Center, Box 25046, MS980, Lakewood, CO, 80225, USA, Phone 303-236-5509, Fax 303-236-5349, clow@usgs.gov
2Earth Surface Dynamics, U.S. Geological Survey, Denver Federal Center, Box 25046, MS980, Lakewood, CO, 80225, USA, Phone 303-236-5509, Fax 303-236-5349, furban@usgs.gov
The GCOS steering committee recently (1999) approved the development of a globally comprehensive permafrost network to detect temporal changes in the solid-earth component of the cryosphere. The International Permafrost Association (IPA) immediately took responsibility for managing and implementing the Global Terrestrial Network for Permafrost (GTN-P), as part of the Global Terrestrial Observing System (GTOS). GTN-P has two primary observational components: 1) the permafrost's active-layer, and 2) the thermal state of the underlying permafrost. Active-layer monitoring is generally accomplished using automated surface instrumentation while the thermal state of deeper permafrost is determined through periodic temperature measurements in boreholes. 13 countries are currently involved in this effort.
In this paper, we focus on the portion of the GTN-P network contributed by the U.S. Department of the Interior. DOI participates in both aspects of GTN-P with active-layer monitoring stations spanning northern Alaska and a 21-element deep borehole array in the National Petroleum Reserve Alaska (NPRA). The first stations in the active-layer network were installed during 1998. Although the records from the AL network are still too short to identify trends, anomalous periods can already be identified. The AL network records also provide a basis for understanding signals detected in the deep borehole array. The DOI/GTN-P borehole array is the largest array of deep boreholes in the world currently available for monitoring the thermal state of deep permafrost. Periodic temperature measurements in the boreholes began in the late 1970's, soon after the array was drilled. Near-surface temperature fluctuations across the array were generally small during the 1980's, except for a short cold period during 1983-84. The situation changed dramatically during the 1990's. Beginning in 1989, coincident with a large change in the Northern Hemisphere Annular Mode - NAM, temperatures began warming across the array. By 2002, near-surface permafrost temperatures had warmed an average of 3 K (mean-annual) across the array relative to 1989; during this period, permafrost temperatures along the coast warmed 1-2 K while those at some interior sites had warmed 4-5 K. Records from the active-layer network (beginning 1998) show a strong sensitivity of permafrost temperatures to the thickness and duration of the seasonal snowpack. At this point, it is unclear how much of the warming detected in the boreholes during the 1990's was due to air temperature changes and how much is due to changes in the seasonal snowpack. Comparison with other records may provide the answer.
Abstract Categories: Changes on Land
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