HR: 08:45h
AN: C11A-04    [PDF]
TI: Establishing Permafrost Temperature Data Reanalysis
AU: * Romanovsky, V E
EM: ffver@uaf.edu
AF: Geophysical Institute UAF, 903 Koyukuk Dr POB 757320, Fairbanks, AK 99775 United States
AU: Sazonova, T S
EM: ftts1@uaf.edu
AF: Geophysical Institute UAF, 903 Koyukuk Dr POB 757320, Fairbanks, AK 99775 United States
AU: Tipenko, G S
EM: ffgst@uaf.edu
AF: Geophysical Institute UAF, 903 Koyukuk Dr POB 757320, Fairbanks, AK 99775 United States
AB: Permafrost has received much attention recently because surface temperatures are rising in most permafrost areas of the earth, bringing permafrost to the edge of widespread thawing and degradation. The thawing of permafrost that already occurs at the southern limits of the permafrost zone can generate dramatic changes in ecosystems and in infrastructure performance. All observed and predicted changes in permafrost stress the necessity to monitor its dynamics (particularly its temperature) for timely assessment and predictions of the possible negative impacts of permafrost degradation on ecosystems and infrastructure. The effects of human-induced disturbances will also be enhanced with climate warming. Permafrost temperature data reanalysis should be included as a very important component in the recently developing within the Global Terrestrial Network for Permafrost (GTN-P) of GCOS/GTOS WMO system for comprehensive monitoring of permafrost temperatures. In this modeling method that was developed at the Permafrost Lab of the Geophysical Institute, University of Alaska Fairbanks, variations in the air temperature and snow cover thickness and properties are the driving forces of the permafrost temperature dynamics. The model is calibrated for a specific site using measured permafrost and active layer temperatures (usually several years of available data are used) and data from the closest meteorological station for the same time interval. The calibrated model can then be applied to the entire period of meteorological records at this station, producing a time series of permafrost temperature changes. The same calibrated model can be applied for predictions of the future permafrost dynamics when some future climate change scenario is used as input data. The historical permafrost data from the Barrow Permafrost Observatory provide a unique opportunity to independently test our model and modeling results. One of the best examples of such historical data set is the permafrost temperature data that were obtained during the 1950s and early 1960s by Max Brewer of USGS in Barrow region. Those measurements were of very high quality, with a precision of generally 0.01oC. A specific numerical model for the Barrow permafrost temperature regime was developed in 1997 at the GI Permafrost Lab. The model was calibrated using data from shallow (down to one meter) soil temperatures obtained by Ken Hinkel at a Barrow site with surface conditions similar to the Brewer site. No data from the Brewer sites were used for the calibration. The daily air temperatures and snow cover thickness during the entire period of measurements (1924-2001) at the Barrow meteorological station were used as input data for this calibrated model. As a result, a time series of daily ground temperatures for the depths between 0 and 200 meters were obtained. To compare calculated temperatures with measured data, we used the time interval between September 1951 and October 1952, when weekly measurements were available. The results of this comparison were much better than expected. For the entire period, which covers more than one year, the differences between calculated and measured permafrost temperatures were typically smaller than 0.3oC in the depth interval between 2 and 18 meters. They practically never exceeded 1oC in the upper two meters of soil and permafrost. The same approach of permafrost temperature data reanalysis was used for many other sites in Alaska and in the Russian Arctic and Sub-Arctic. The results of reconstruction of the permafrost temperature dynamics in 20th century and forecasts for the 21st century based on this approach for the Fairbanks, Barrow, Yakutsk, Tiksi, and Vorkuta sites will be presented.
DE: 1615 Biogeochemical processes (4805)
DE: 1823 Frozen ground
DE: 1863 Snow and ice (1827)
DE: 3322 Land/atmosphere interactions
DE: 3344 Paleoclimatology
SC: Cryosphere [C]
MN: 2003 Fall Meeting