Permafrost

The sensitivity of Tibetan Plateau climate to changes in NDVI-derived
vegetation properties
Lixin Lu and Tingjun Zhang
(Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80523)
Abstract: The spatial distribution of vegetation properties strongly influences the energy,
water, and carbon exchanges at the land-atmosphere interface. Recent studies have shown that
there are noticeable trends over Tibetan Plateau in surface-meteorology-station observed
screen-height air temperatures and precipitation (Frauenfeld et al, 2005), and in the satellite
remotely sensed land-cover features such as NDVI (Chu et al., 2006; Fan et al, 2006), and
surface skin temperatures (Oku et al., 2006). These observational evidences indicate the
possible amplified climate change signals over the elevated plateau-region.
To understand the mechanisms driven Plateau-wise climate variations and monsoon
dominated moisture balance, year-long simulations are performed using Colorado State
University Regional Atmospheric Modeling System (CSU RAMS) for 1995. Our coarse grid
covers entire China, and part of Japan, Mongolia, and southern Asian countries at 100-km
grid-spacing, and finer-grid focuses on the Tibetan Plateau region at 25-km grid-increment. The
year 1995 is chosen because it is an average year in terms of screen-height air temperatures and
precipiations. ECMWF reanalysis product is used to provide atmosphericinitial and lateral
boundary conditions for our simulations. The GIMMS 8-km NDVI products are processed to
describe vegetation growth states. The sensivitiy experiments are performed by increasing and
decreasing the NDVI value to 25% of their original values. At the first glance, our model is
doing a reasonable job in reproducing 2-m air temperature observed at local met-stations. The
preliminary results also indicate that the penetration of monsoon moisture is sensitive to
vegetationdescription, and thereby the biosphere-atmosphere feedbacks.
Further numerical experiments will be performed to evaluate the impact of land use and
land cover change to Tibetan Plateau climate.Sensitivities of simulated climate to perturbations
of vegetation spatial distribution, topography, and sea surface temperatures will also be
evaluated.
Key words: Sensitivity, climate , NDVI-derived vegetation properties
Hydrogeochemistry of the Ak-shirak Range glacier waterflows
(Central Tien Shan)
Makarov V.N.
(Permafrost Institute SB RAS, Yakutsk, Russia, makarov@mpi.ysn.ru)
Abstract: Processes of chemical composition formation of mountain rivers are still rather
unexplored. Various chemical composition of glaciers ice, various degree of their contamination
with morainic material and uneven ratio of demineralization activity and concentration hinder
the geochemistry studies of glaciers waterflows. The results of geochemical studies of surface
waterflows that spring from under the Ak-shirak Range glacier are given in the paper.
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