The estimation of dielectric constant of frozen soil-water mixture at microwave bands
The estimation of dielectric constant of frozen soil-water mixture at microwave bands
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DOI：
10.1109/igarss.2003.1294626
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发表时间：
2003-07
期刊：
影响因子：
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通讯作者：
Lixin Zhang;Jiancheng Shi;Zhongjun Zhang;K. Zhao
中科院分区：
文献类型：
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作者：
Lixin Zhang;Jiancheng Shi;Zhongjun Zhang;K. Zhao
微波遥感是一种很有前途的方法，用于检测土壤表面冻结和融化时，由于介电常数的变化。在冻土中，并非所有的液态水都在0/spl deg/C或以下冻结。在半经验的土壤-水混合物介电混合模型的基础上，将其推广到冻土介电常数随温度的变化。经验函数Wu = A/spl middot/|T-273.2|/sup-B/已被用于估算冻土中液态水和冰的分数，其中Wu为未冻水含量。A和B是与土壤质地有关的参数，T是以K表示的温度。在半经验混合模型中增加了冰组分介电常数的计算项，并将有关参数扩展到0/spl ℃以下。因此，通过获得液态水含量和冰含量，可以估算冻土的介电常数。模拟结果表明，土壤的介电常数在冻融过程中会发生急剧的变化。研究结果可用于分析土壤在冻融过程中微波频率的发射和散射特性。
The microwave remote sensing is a promising method for detecting the freezing and thawing of soil surface due to change of dielectric constant when frozen. In frozen soil, not all liquid water freezes at or below 0/spl deg/C. Based on the semi-empirical dielectric mixing model for soil water mixture, an extension of model has been made to describe the dielectric constant change of frozen soil as a function of temperature. An empirical function Wu=A/spl middot/|T-273.2|/sup -B/ has been used for estimating the fractions of liquid water and ice in frozen soil, where Wu is unfrozen water content. A and B are parameters related to soil texture, T is temperature in K. The item for calculation of dielectric constant of ice fraction is also added to the semi-empirical mixing model with extension of some related parameters adapted to temperature range below 0/spl deg/C. Thus, with obtaining of liquid water content and ice fraction, the dielectric constant of frozen soil may be estimated. The simulated data shows that the dielectric constant of soil has a sharp change while freezing or thawing occurring. The results could be used for analyzing the characteristics of emission and scattering of soil at microwave frequencies during freezing and thawing.