Abstracts for the 5th International GAME Conf.
3-5 October 2001
Aichi Trade Center
Nagoya Japan
CRYOGENESIS AND CHANGES IN ENERGY AND WATER EXCHANGE IN THE ACTIVE LAYER, MIDDLE LENA BASIN (RESULTS AND PROBLEMS)
Ugarov Innokentyi (1), Gavriliev, Peter (1)
(1) Melnikov Permafrost Institute, Russian Academy of Sciences
1. Rapid changes in climate parameters during the period 1993-2000 intensified non-uniform cryogenic redistribution of moisture and heat in the active layer both vertically and horizontally. This was one of the main characteristic features of energy and water exchange in the active layer of permafrost. For example, moisture content and moisture storage varied over a season 3-7 times in the upper root-inhabited layer (0-0.5 m) and 1.5-2.5 times in the layer of seasonal thaw.
In 1995-1997 and 1999-2000, rainwater caused saturation to the entire depth of the active layer on most sites. It resulted in horizontal water movement along micro- and meso-relief forms at sites Spasskaya Pad, Kerdyugen, Dyrgabai Ataga, Menaika, and others.
2. Based on the results of experimental studies, three zones of heat and water redistribution along the profile of the active layer have been identified.
Our estimates suggest that rainwater percolation may cause an increase in mean annual ground temperature by 0.8-1.0C and in active layer thickness by 0.14-0.35 m below undisturbed forest and by 0.4 m below plough fields. These values quantify the convective effect in the active layer thickness variations in 1997 and 1998 resulting from the activation of cryogenesis in response to abrupt climatic fluctuations.
3. Quantitative data on interannual variability of heat losses and gains at seasonal thawing and freezing are presented for various landscapes.
4. The effect of snow depth variation on the rate and depth of seasonal freezing is estimated using two independent methods.
5. Interannual variation of the active layer thickness does not exceed 25-33% from the long-term average. On disturbed sites, the trend of the active layer may be positive or negative depending on weather, terrain, surface cover, duration of water stagnation, and so on.
6. The results of our investigations show that the magnitude of changes in the active layer parameters due to present-day climatic change is much greater than it was previously thought.
7. The problems requiring further research are discussed.
Submittal Information
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Melnikov Permafrost Institute, Russian Academy of Sciences | |
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Yakutsk-10, Permafrost Institute | |
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