Permafrost

114
Theme 3. Climatic, environmental and
cryospheric changes
Evaluation of permafrost seasonal variations at several Asian sites in
21 st century
A.B.Shmakin 1 , A.A.Vasiliev 2
(1. Institute of Geography, Russian Academy of Sciences;
2. Institute of Cryosphere, Russian Academy of Sciences)
Abstract: Several series of numerical experiments has been carried out using a detailed
soil-snow-vegetation-atmosphere transfer (SVAT) model involved in PILPS and alike
international projects. Input meteorological variables were specified for some possible
scenarios of future climate change in Eurasia. The meteorological time series combine both
contemporary variability on daily to annual basis, and interdecadal trends of the parameters.
The SVAT model allowed us to evaluate changes in snow cover features, temperature regime of
snow and soil, and permafrost thawing depth under climate change conditions at several
locations tested for the study. The experimental sites are located in permafrost areas of Siberia
and Tibet, and are characterized with different natural conditions.
Under various warming scenarios, the snow parameters on permafrost sites don’t change
considerably, although the snow season shortens to some extent. At the same time, at some sites
the snow depth increases due to larger precipitation in winter, which results in slightly higher
permafrost temperatures in winter. Average depth of permafrost seasonal thawing for tested
sites is examined. Its change under warming scenarios strongly depends on local landscape
features: presence and depth of peat and/or moss layer on the top of the soil profile, specifics of
thaw water dynamics in the soil, etc. The peat/moss layer acts as insulator and prevents fast
thawing, which is typical for some Siberian sites, and rather rare for Tibet. The thaw water can
re-freeze on the top of the frozen ground, thus making deeper thaw more difficult. This process,
however, depends on the local hydrological regime in the soil, and plays important role not
everywhere.
The study was supported by the Russian Foundation for Basic Research (grant
04-05-64745) and by INTAS (grant No. 03-51-5296).
Key words: Permafrost, numerical modeling, Asia, land cover features