青海南部冻融区高寒草地土壤温度变化及热量传输特征

为进一步了解高寒地区草地土壤冻融期（5—9月为融期,10月—翌年4月为冻期）能量收支平衡及不同剖面物理属性过程,采用热传导对流法、振幅法和相位法就该区不同深度土壤热通量分别进行了计算,并初步分析了不同年际间土壤热力学参数的变化特征。结果表明,热传导对流法能较好地描述高寒地区不同深度土壤热通量的变化特征。不同深度土壤温度的多年平均值由地表向深层土壤逐渐呈滞后效应,地表温度（T_0cm）最高值出现在7月份左右,而深层土壤T_160cm和T_320cm的最高值出现时间分别为8月和9月,且随着土壤深度的增加,其振幅减小,相位滞后。中间层土壤温度实测值与模拟值的拟合效果最佳,回归校正系数分别为0.9361、0.9509和0.9133;土壤总热通量与对流热通量相位的变化趋势一致,而与传导热通量相反。因此,季节变化是影响该区土壤剖面热量传递过程和传输方向的主导因子。

The characteristics of soil temperature variations and heat exchange in freeze-thaw period over southern alpine grasslands in Qinghai province

To understand the energy balance and physical attributes of different profile process of alpine grassland soil freeze-thaw period furtherly, the methods of heat transfer, the amplitude and phase on soil heat flux of the different depth were calculated in this paper, and the parameters of soil thermodynamic characteristics during different years were analyzed. The results showed that the method of heat transfer could well describe the variation characteristics of soil heat flux of different soil layers. Average soil temperature of different depths from the surface to the depths gradually showed the hysteresis effects, meanwhile, the surface (T_0cm) maximum temperature appeared about July, however, the highest temperature occurrence time of the deeper soil T_160cm and T_320cm appeared August and September, respectively. With the increase of soil depths, its amplitude decreased and the phase delayed. The fitting effect of the measured temperature and the simulation was the best in the middle soil layers, and the correction coefficients were 0.9361, 0.9509 and 0.9133, respectively. In addition, the phase change trends of soil total heat flux and the convective heat flux were similar, but in contrast to the conduction heat flux. Therefore, seasonal change was the dominant factor of affecting on the heat transfer process and the transfer direction of soil profiles.