permafrost table

permafrost table

[′pər·mə‚frȯst ‚tā·bəl]
(geology)
The upper limit of permafrost. Also known as pergelisol table.
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In 1969-71, he placed thermistors to measure the temperature below the permafrost table at 10 sites near the Garry cabin and ran several hundred metres of Z-cable into the building to capture the data on chart recorders.
O modelo "crioestatico" envolve duas frentes de congelamento movendo em direcoes opostas, para baixo da superficie e para cima do permafrost table, causando pressao nos materiais descongelados presentes entre as frentes de congelamento.
The surface layer in permanently frozen peatlands is more complicated, but probably can be thought of as having at least two distinct subunits, because the depth to permafrost table and depth to water table may be the same during dry periods and the water table can lie above the permafrost table during wet periods (Vardy et al.
This difference results in rapid heat loss in winter and slower heat penetration in summer, and it accounts for the thermal offset between the ground surface and the permafrost table (Romanovsky and Osterkamp, 1995).
This boundary can be considered the long-term permafrost table.
As thaw frequency decreases with depth, the probability of thaw at the long-term permafrost table approaches zero.
Therefore, the tops of primary ice wedges indicate the maximum depth of thaw that has occurred since the ice wedges formed, which coincides with the long-term permafrost table and the base of the transition zone.
Vegetation and organic debris tend to insulate the ground and thus reduce heat flow to depth, while surface aggradation is accompanied by upward migration of the permafrost table.
Lowering of the permafrost table has the potential to make soluble salts available for transport.
On the other hand, the estimate of 30 years could be too short; 1996 was a wetter year than average, and further release of Na+ from the permafrost will occur as surface erosion of the unvegetated slope continues and the permafrost table falls.
Another way that salts could be released as a result of permafrost degradation is through the effects of climatic warming: warming causes a general lowering of the permafrost table, allowing transport of soluble material from the newly thawed soil and ground ice by wash processes.