羌塘高原核心区2013-2014年土壤温度变化特征

Characteristics of soil temperature variation in core region of Northern Tibetan Plateau in China during 2013-2014

基于羌塘高原核心区布设的19套土壤温湿度仪器和3个自动气象站2013年9月-2014年10月间的监测数据,分析羌塘高原核心区不同站点在1 cm、10 cm、20 cm深度处的土壤温度日变化和季节变化特征。结果表明:(1)研究时段内站点1 cm、10 cm、20 cm深度土壤的日均温在-16.27~17.18℃之间波动,随着土壤深度的增加,温度变幅逐渐减小。(2)站点间的日均温差最大不超过12.82℃,主要受海拔与纬度的影响。昼夜变化呈现升温快,降温慢的特征。(3)不同深度的土壤平均最冷月均温为-12.69℃,最暖月均温为13.15℃,土壤日平均温度的年际变幅在30℃左右。在土壤冻结/消融过程中土壤温度的变异系数很高,表层更加明显,且消融过程变异性比冻结过程更强。(4)在月尺度上土壤1 cm日平均温度与气温的相关性最强,可达到0.99以上。研究将有助于填补该地区土壤温度数据的空白,对认识该区域冰冻、消融交替过程中土壤热量迁移的连续变化也有重要的意义。

A total of 19 soil temperature stations and three automatic weather stations in Gaize and Ritu counties, Tibet within the core region of Northern Tibetan Plateau, have been established to measure soil temperature at three soil depths（1 cm, 10 cm and 20 cm） with their elevations varying from 4515 to 5172 m. The station-averaged soil temperature data at hourly to monthly scale are used to analyse the characteristics of soil temperature and thaw-freezing processes during the period from September, 2013 to October, 2014. Major findings are as follows： The ranges of daily soil temperature at 1 cm, 10 cm and 20 cm depths are-16.27 to17.18 ℃,-14.35 to 15.75 ℃, and-13.49 to 14.70 ℃, respectively during the study period. Soil temperature varied in a slower amplitude with the increase of depths. The difference of 22 stations may have relationship with elevation and latitude, and the spatial variability is less than12.82 ℃. The temperature continuous rising process is faster than continuous cooling process at daily scale. For all the three depths of soil temperature, the coldest month is January with an average temperature of-12.69 ℃, and the warmest month is July with an average temperature of 13.15 ℃. The annual range of daily mean temperature is about 30 ℃. The soil temperature has a strong coefficient of variation（CV） values during thaw phase and freezing phase,especially at 1 cm soil depth. And the CV values during the thaw phase are higher than those during the freezing phase. In view of the correlation analysis between air temperature and soil temperature at three soil depths, the soil temperature at 1 cm depth is strongly correlated with air temperature at monthly scale with the correlation coefficient being r = 0.99. The results will provide reliable data for the basic research of the Tibetan Plateau. And it will also provide a scientific basis for regional thaw phase and freezing phase, soil heat transfer and hydrological and thermal process.