青藏高原沙区地温研究

青藏高原沙区测温结果表明:沙丘下和厚沙层覆盖地段下的地温较邻近天然无沙地表有所升高,而薄沙层覆盖地段下的地温反而比天然无沙地表有降低的趋势。

STUDY ON THE GROUND TEMPERATURE OF SANDY AREA IN THE QINGHAI-XIZANG PLATEAU

The sandy areas of Qinghai-Xizang Plateau mainly distribute on the valley, around lakes and on flat surface of the plateau. Semi-fixed and moving dunes are the predominant types and they interlaced with erosioned interdunal depressing. The moving dunes are frequently in the form of crescent dune and barchan chain. The results from observation and study for many years in this region prove that not all the ground temperature in sandy areas are higher than that in non-sand areas. Dry sand grains with low specific heat and high heat conduction own very strong heat-absorbing and heat-giving fields. The relation between sand cover and frozen soil like snow cover on plateau exists the duplicity of hightening and lowering ground temperature. The function of sand cover absorbing or giving off heat is decided by the thick of sandy layer. When considerable thick of sand covering ground, the radiant energy absorbed by surface sand is directly conducted downward or carried by infilting rainwater to underlying stratum, which results in ground temperature raising. While in thin sand-cover area, the transporting of radiant energy is certainly limitted due to the difference between sandylayer and underlying rock on thermodynamics and infiltration. In cold season, the function of surface sand giving off heat is obviously stronger than that of the other rocks, which forces the underlying stratum giving off more energy than the same stratum in non-sand cover area; finally, the annual ground temperature of shallow layer in thin-sand cover area is lower than that in non-sand cover area.