【摘要】 利用2014年7月至2015年1月黄土高原地区土壤含水量和土壤热性质观测资料,分析了该区域土壤热性质及其变化特征,并讨论了降水对土壤热性质的影响,结果显示:(1)除10 cm外,各层土壤热扩散率整体上呈现夏季下降,秋季平稳,冬季上升三个阶段,土壤体积比热容和土壤导热率表现为夏季上升,秋季平稳,冬季下降的趋势;100 cm处的土壤热扩散率始终高于40 cm,土壤热扩散率不随土壤深度增加而线性增加。(2) 5 cm与10 cm层的土壤热性质均有明显日变化特征,且振幅较大,40 cm与100 cm处的日变化振幅逐渐变小。由于10 cm层土壤含水量的波动最大,该层的土壤热性质变化波动也最大。(3)土壤温度与土壤热扩散率随降水增加而下降,土壤热扩散率下降主要是土壤含水量较高时,土壤导热率与土壤体积比热容变化的幅度不一致所致;土壤体积比热容与土壤导热率随降水量增加而上升,降水主要通过土壤含水量的变化影响土壤热性质。更多还原

【Abstract】 The temporal variation of soil thermal properties and the response to precipitation in a typical cropland are analyzed during a period from July 2014 to January 2015 over Loess Plateau.The flat and relatively wide loess area is the simplest underlying surface of the Loess Plateau.It is important to understand the land-atmosphere interactions over the loess area and then further promote the study to other underlying surfaces over the Loess Plateau.The underlying surface of the Pingliang Land Surface Process and Severe Weather Research Station,Chinese Academy of Sciences is typical loess area which offered meteorological and land surface observation data to many researches.This study cannot represent the whole loess plateau but can provide reference to understand the water and heat exchange process on land surface.The results are as follows :(1) In addition to 10 cm,the soil thermal diffusivity decreasing in summer,almost keeping stabilization in autumn and increasing in winter,while soil temperature shows a downward trend in this duration.Linear growth is not found between the soil thermal diffusivity and soil depth,although the soil thermal diffusivity at 100 cm depth is always higher than that one at 40 cm depth in the total study period.(2) The soil thermal properties at 5 cm and 10 cm layers are varied significantly and the daily variation amplitude of soil thermal properties at 40 cm and 100 cm gradually decrease.Influenced by the fluctuation of soil water content,soil thermal properties at 10 cm fluctuated the most among four layers.(3) The soil thermal properties at 5 cm change significantly with precipitation.The soil volumetric heat capacity and thermal conductivity change inconsistently when soil water content is high will lead to a decrease of soil thermal diffusivity,and the soil volumetric heat capacity and thermal conductivity increase with the increase of soil water content.There is a positive relationship between the soil volumetric heat capacity and thermal conductivity.Precipitation mainly affects the soil thermal properties through changes in soil water content.更多还原