塔中地区不同类型沙丘浅层地温观测

Observation of Ground Temperature at Shallow Layer of Different Dune Types in the Tazhong Area

2009年8月3～10日,通过对塔中地区流动沙丘和人工固定沙丘的地温测量,获得了不同深度的地温数据:①夏季无论人工固定沙丘,还是流动沙丘表面地温的日较差都很大,日较差随着深度的增加逐渐变小,特别在沙丘20cm深度处,地温的日较差较小;②人工固定沙丘在相同深度的温度要比流动沙丘低;③在夏季地温和气温差值较大,出现了一年中最大值;④无论固定沙丘还是流动沙丘,风速对其表层温度的影响都较大。

Land surface temperature affects the capability of long wave radiation,and it is an important parameter for studying climate change. The variation of air temperature and precipitation was often stressed in studying climate change in the Taklimakan Desert in the previous studies,but ground temperature in the desert was infrequently studied. In this paper,MicroLite 16K LITE5016 was used to examine the spatial distribution and temporal variation of ground temperature at shallow layer of different dune types in the Tazhong area located in the central Taklimakan Desert,where oceanic airstream is difficult to arrive. The Tazhong area is characterized by a typical continental climate with frequently and intensely wind-blown sand movement. The area of mobile dunes in Tazhong occupies more than 80% of the total area of the Taklimakan Desert. Temperature variation here is drastic,the maximum temperature is as high as 45.6 ℃,and the diurnal-nocturnal temperature difference is over 40 ℃. The annual sunshine duration in this area is 2 700 hours,accumulated temperature ≥0 ℃ is over 4 000 ℃,and the total solar radiation is 5 700-6 000 MJ/m2. Precipitation in this area is low,the annual precipitation is no more than 50 mm and only 4-5 mm in minimum,and it is extremely arid climate. The values of ground temperature at different depths （0 cm,10 cm and 20 cm） over a mobile dune and an artificially-fixed dune in the Tazhong area were measured during the period from August 3rd to 10th,2009. The results are as follows：（1） Daily range of ground surface temperature was high in summer both for mobile dune and artificially-fixed dune,it was decreased with the increase of depth,and it was the lowest at depth of 20 cm; furthermore,the maximum ground temperature occurred 2 hours later from noon,and the minimum one occurred at dawn; （2） The ground temperature of artificially-fixed dune was lower than that of mobile dune; （3） The difference between ground temperature and air temperature was the highest in summer; （4） Wind speed affected significantly the ground surface temperature regardless of mobile dune or artificially-fixed dune.