塔克拉玛干沙漠腹地土壤热通量变化特征

利用2009-2011年塔克拉玛干沙漠大气环境观测试验站测得的土壤热通量数据，分析了塔克拉玛干沙漠腹地土壤热通量在不同天气条件下的变化特征。结果表明：（1）塔克拉玛干沙漠腹地1 cm处土壤热通量年平均值为1.9 W·m^-2，5、20、40 cm处分别为1.0、0.4、0.4 W·m^-2；1 cm处土壤热通量年最大值为334.1 W·m²，年最小值为-184.2 W·m^-2；土壤热通量基本表现为夏季 > 春季 > 秋季 > 冬季。（2）各土层土壤热通量具有明显的日变化特征。随着土壤深度的加大，土壤热通量的日变化幅度明显减小，最大值出现的时间有一定的滞后性。土壤热通量5 cm出现最大值的时间比1 cm处延迟3 h，延迟速率为0.75 h·cm^-1，20 cm比5 cm出现最大值的时间晚2 h，延迟速率约为0.13 h·cm^-1。（3）不同天气情况下的土壤热通量日变化特征有一定的差异，晴天较为规则，阴天、雨天、沙尘天则较不规则，且1 cm处土壤热通量受天气影响最显著。晴天1 cm处土壤热通量平均值为9.0 W·m^-2；阴天、雨天、沙尘天1 cm处土壤热通量值平均值分别为5.1、-6.1、-1.9 W·m^-2。

Characteristics of Soil Heat Flux in the Hinterland of the Taklimakan Desert

Based on the soil heat flux data during 2009-2011 from the Taklimakan Desert Atmosphere and Environment Observation Experiment Station, characteristics of soil heat flux of the Taklimakan Desert hinterland was analyzed. The result showed that:(1) Annual mean soil heat flux at the depth of 1 cm of the Taklimakan Desert was 1.9 W·m², while at the depth of 5 cm, 20 cm and 40 cm were 1.0 W·m², 0.4 W·m², 0.4 W·m², respectively; The annual maximum soil heat flux at the depth of 1 cm was 334.1 W·m², and the annual minimum soil heat flux at the depth of 1 cm was 184.2 W·m²; The maximum value of soil heat flux was in summer. (2) The diurnal variation was obvious for soil heat flux at different levels. The daily range of soil heat flux obviously reduced with the deepness of soil depth, and there was a certain hysteresis for the time when maximum soil heat value appeared. The time at the depth of 5cm was 3 hours later than the depth of 1cm, and the time at the depth of 20 cm was 2 hours later than the depth of 5 cm.(3) The diurnal variations of soil heat flux under different weather processes have some differences with regular variation on sunny days while irregular variation on cloudy, rainy and dust days. The soil heat flux at the depth of 1 cm was significantly affected by the weather process. The mean soil heat flux at the depth of 1 cm was 9.0 W m² on sunny day, and the mean soil heat flux at the depth of 1 cm on cloudy, rainy and dust days were 5.1 W·m², -6.1 W·m², -1.9 W·m², respectively.