HR: 11:05h
AN: C32A-04    [Abstracts]
TI: Soil Temperature Reemergence in Permafrost
AU: Zhang, T
EM: tzhang@nsidc.org
AF: National Snow and Ice Data Center (NSIDC), 449 UCB, University of Colorado, Boulder, CO 80309-0449, United States
AU: * Schaefer, K
EM: kevin.schaefer@nsidc.org
AF: National Snow and Ice Data Center (NSIDC), 449 UCB, University of Colorado, Boulder, CO 80309-0449, United States
AB: Soil temperature reemergence is the disappearance and subsequent reappearance of near surface soil temperature anomalies, driven by soil freeze-thaw processes. Reemergence of past soil temperature anomalies is a new class of time-delayed, land-atmosphere feedbacks influencing surface fluxes of latent and sensible heat. Anomalous energy is stored, isolated from diffusion processes, as variations in latent heat of fusion. Schaefer et al. [2007] found that past soil temperature anomalies in seasonally frozen soils are stored as variations in the amount of ground ice and can reemerge at the surface after soil thaw in spring. Schaefer et al. [2007] also hypothesized that temperature anomalies in permafrost would be stored as variations in the active layer depth, reappearing after the soil column completely freezes in winter. Essentially, a warm summer produces a deeper active layer, which requires more energy to freeze in autumn, resulting in warmer soils in winter. Here, we explore this hypothesis using statistical analysis of long-term, in situ soil temperature measurements at 37 permafrost hydro-meteorological stations across Siberia. The observations span 30-40 years at depths of 2-320 cm. We also use a simple soil thermodynamic model with phase changes to explore the detailed thermodynamic processes driving temperature reemergence in permafrost.
DE: 0702 Permafrost (0475)
DE: 0704 Seasonally frozen ground
DE: 0706 Active layer
SC: Cryosphere [C]
MN: 2007 Fall Meeting