HR: 11:10h
AN: C22A-04    [Abstracts]
TI: Observed Changes and Drivers of Permafrost Temperatures in Northeastern Siberia
AU: * Frauenfeld, O W
EM: oliverf@colorado.edu
AF: University of Colorado CIRES/National Snow and Ice Data Center, 449 UCB, Boulder, CO 80309-0449 United States
AU: Zhang, T
EM: tzhang@nsidc.org
AF: University of Colorado CIRES/National Snow and Ice Data Center, 449 UCB, Boulder, CO 80309-0449 United States
AU: Barry, R G
EM: rbarry@nsidc.org
AF: University of Colorado CIRES/National Snow and Ice Data Center, 449 UCB, Boulder, CO 80309-0449 United States
AU: Gilichinsky, D
EM: gilichin@issp.serpukhov.su
AF: Soil Cryology Laboratory Institute of Physico-Chemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino, 142290 Russian Federation
AB: Permafrost temperature is an important indicator of climate change, especially in high-latitude environments. It is linked to the climate through the ground surface, vegetation, snow cover, and the active layer. Long-term permafrost temperature measurements at five depths (0.2 m, 0.4 m, 0.8 m, 1.6 m, and 3.2 m) are investigated for the continuous permafrost region of the Russian Arctic, from approximately 115°E-160°E and 60°N-70°N. These in situ measurements are based on station records from 37 sites, dating as far back as 1915 and extending through 2000. However, the 1960-1996 period is more reliable, and is thus the focus of this investigation. We find that across all depths, on an annual basis permafrost temperatures have been experiencing a statistically significant increase, with greatest changes near the surface (0.6°C/decade) and the smallest change at 3.2 m (0.3°C/decade). On a seasonal basis, changes are greatest during winter (0.2 to 1.3°C/decade), followed by spring, then summer, and the smallest temperature changes are observed during autumn. We next evaluate the degree to which these changes are driven by air temperature, snow depth, as well as warm-season precipitation. During winter, permafrost temperature increases are driven by snow cover and air temperature, while summer increases are related to air temperature and perhaps precipitation. Cold-season permafrost temperature increases are therefore partly due to the insulating effects of increased snow depths in northeastern Siberia, while the warm-season permafrost temperature increases illustrate the importance of air temperature, as well as soil moisture. However, part of the summer time changes are likely also due to soil "memory" effects, related to the higher winter permafrost temperatures.
DE: 0702 Permafrost (0475)
DE: 0770 Properties
DE: 0774 Dynamics
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
SC: Cryosphere [C]
MN: Fall Meeting 2005