THE EFFECT OF PRECIPITATION ON INTERANNUAL VARIATION IN UPPER PERMAFROST TEMPERATURE, GAME STUDY AREA, CENTRAL YAKUTIA
Konstantinov, Pavel (1)
(1) Melnikov Permafrost Institute, Russian Academy of Sciences
The study area is situated in the Lena-Kenkeme interfluve, 25 km north-west of Yakutsk (Central Yakutia, East Siberia, Russia). In terms of geomorphology, the area is a bedded aggradation plain with elevations 200-220 m a.s.l. The vegetation is middle taiga dominated by larch forest. The active layer and the near-surface permafrost consist mainly of clayey loam, sandy loam, and sand. The study area lies within the zone of continuous permafrost. Mean annual permafrost temperature is -2.0 to -3.5C for the undisturbed condition.
During the 1996-2000 study of taiga landscapes, data were obtained on the effect of precipitation on interannual temperature variation in the upper permafrost layers (at 3-7 m depth). No significant interannual variability of air temperature occurred over the period of investigations. In 1997, 1998 and 1999, there was however an increase in late-fall liquid precipitation and in winter snowfall. As a result, the pre-winter moisture content of soils increased 2.5-6 times and the maximum snow depth increased 1.3-1.5 times (2-2.5 times on the onset of winter) compared to the first year of observation (1966). This caused a lengthening of the seasonal frost penetration period by 1-3 months and a respective shortening of the period of ground cooling below the active layer in the years 1997, 1998 and 1999. The amplitude of annual temperature fluctuation in the upper permafrost was thus reduced by a factor of 1.3-2.3, and the mean annual ground temperature increased by 1.4-1.6C.
It appears that the large interannual variation in the upper permafrost temperature was caused by changes in the amount and regime of precipitation against a background of the relatively stable thermal regime of air during the period of observation.
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Konstantinov, Pavel
30-May-01-19:23:46
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Melnikov Permafrost Institute, Russian Academy of Sciences
