摘要
青藏高原冻土区地温既受海拔、纬度和经度（干燥度）区域地带性规律控制，同时它又受植被、雪盖、砂层、水被和地质构造等局地因素的显著影响。局地因素对地温的影响具有双重性：在不同域值条件下，它可增高或降低地温。沙丘下和较厚（〉10～20cm）砂层覆盖下的地温较邻近天然无砂层地段高；而薄（〈10～20cm）砂层覆盖下的地温反而比天然无砂地段有降低的趋势。在同一地貌单元内，沼泽湿地处地温最低，有利于多年冻土形成和保存；淡水湖塘和河流均能升高地温，加大融化深度，不同程度地形成融区。但是，盐湖由于其热传导水层结构，有助于形成和保护湿寒土。总之，每种局地因素迫使地温向相反方向转化阶段是一个区间值，为渐变过程。随时空尺度变化，局地因素的影响变化很大。有些地段，几种局地因素共同作用，加上活动构造和地形地貌等的影响，使地温的时空分布和局地因素对其影响或控制变得错综复杂。因此，研究和预测地温特征和变化趋势，需要在监测砂层和水被影响的基础上进行参数选择、验证和优化。
Ground temperatures in permafrost regions on the Qinghai-Tibet Plateau are controlled by regional zonations of elevation, latitude and continentality （aridity）. They are also significantly affected by local environmental factors such as vegetation coverage, snow cover, sand layers, and surface water/moisture conditions. However, these influences are dual in that they can increase or decrease ground temperatures under certain circumstances. Temperatures of soils beneath sand dunes and thick （〉10～20 cm） sand layers are warmer than those of adjacent areas without sand coverage. However, temperatures of soils beneath shallow （〈10～20 era） sand layers are cooler than those of adjacent areas without sand coverage. Within a same geomorphological unit, temperatures of soils in the paludified areas or wetlands are generally the lowest, favoring the formation and protection of permafrost. Freshwater lakes and ponds and middle to large rivers tends to increase ground temperatures and to deepen the depth of maximum thaw in summer, resulting in various taliks. However, the salty lakes tend to cool or protect cryopeg because of its conductive water-layer structure. In summary, the influence of each local environmental factor on ground temperatures could reverse in direction at a certain range. That is a gradual process depending on the timing and locality. In some areas, in addition to the impacts from the active tectonics, topography and geomorphology, the influences of several local factors superimpose and further complicate the impacts of local factors on ground temperatures. Therefore, research and forecast of the features and changing trends of ground temperatures need to select model parameters and the models need to be validified and optimized on the basis of monitoring the roles of sand coverage and surface water bodies.
出处
《冰川冻土》
CSCD
北大核心
2008年第4期546-555,共10页
Journal of Glaciology and Geocryology
基金
中国科学院"百人计划"项目
国家自然科学基金项目(40701031)
国家自然科学基础人才培养基金冰川学冻土学特殊学科点特殊人才项目(J0630966)资助
关键词
青藏高原
多年冻土
地温
砂层
地表水体
双重影响
Qinghai-Tibet Plateau
frozen ground
ground temperatures
sand layers
surface waterbodies
dual influences
