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DEVELOPMENT OF A SOIL MOISTURE MODEL FOR USE WITH PASSIVE MICROWAVE REMOTE SENSORS.

机译:开发用于被动式微波遥感器的土壤水分模型。

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摘要

Soil moisture profiles were simulated for a hypothetical loamlike soil with a water and heat balance model. Expected X-band and L-band radiometer response to these conditions were simulated by a radiative transfer model. From these simulations, a model was developed to estimate soil water content in two layers of a 1.5 m soil profile.; Soil water content in the top 21 cm of the hypothetical soil was related to L-band emissivity over a wide range of soil moisture conditions. Inverted soil moisture profiles which result from small rains were classified by use of the rate of change in L-band emissivity one day after the rain. The amount of water added to the soil profile below the 21 cm depth due to percolation was related to a ratio of the rate of change in X-band and L-band emissivities one day after the rain. These relationships were combined into a comprehensive model that predicts soil moisture in two zones of the soil profile.; This model was tested with measurements of soil water content and soil temperature collected during the four seasons of the year in a sandy loam soil contained in an array of lysimeters. X-band and L-band emissivities required in the predictor equations were calculated by the radiative transfer model from measured soil moisture and soil temperature data. The technique developed from simulated results to classify inverted soil moisture profiles was found to be seasonally dependent. It was also found that the second layer algorithm showed seasonal dependence.; Predictions of soil water content in the top 21 cm of the soil profile from L-band emissivity calculated by the radiative transfer model occasionally conformed with measured soil water content. Since the equation to estimate soil water content for inverted soil moisture profiles did not fit the measured data, soil water content on such occurrences was overpredicted. Applications of small amounts of water produced the most disagreement between predicted and measured soil water content.; An equation to predict soil water content in the top 21 cm of the soil profile was developed from an empirical approach to estimate emissivity. Predictions of soil water content with this equation from L-band emissivity estimated by the empirical technique compared very well with measured soil water content regardless of inverted soil moisture profiles or amount of applied water. However, the relationship between amount of water added to the 21 to 150 cm soil layer versus the ratio of the rate of change in X-band and L-band emissivities estimated by the empirical approach still produced considerable data scatter.
机译:利用水和热平衡模型对假设的壤土状土壤水分特征进行了模拟。通过辐射传输模型模拟了预期的X波段和L波段辐射计对这些条件的响应。通过这些模拟,开发了一个模型来估算1.5 m土壤剖面两层中的土壤水分。在广泛的土壤湿度条件下,假想土壤顶部21 cm的土壤水分含量与L波段的发射率有关。小雨造成的土壤水分倒立分布通过使用雨后一天的L波段发射率变化速率进行分类。由于渗滤,在21 cm深度以下的土壤剖面中添加的水量与雨后一天X波段和L波段发射率的变化率之比有关。这些关系被组合成一个综合模型,该模型可预测土壤剖面的两个区域中的土壤水分。通过测量一年中四个季节在渗漏计阵列中包含的沙质壤土中收集的土壤水分和土壤温度,测试了该模型。预测方程中所需的X波段和L波段发射率是通过辐射传递模型根据测得的土壤水分和土壤温度数据计算得出的。从模拟结果发展出来的用于对倒置土壤水分剖面进行分类的技术被发现与季节有关。还发现第二层算法表现出季节依赖性。根据辐射传递模型计算得出的L波段发射率,预测土壤剖面顶部21 cm处的土壤含水量有时与测得的土壤含水量相符。由于估计土壤水分含量反演土壤水分剖面的方程式不适合测得的数据,因此对这种情况下的土壤水分含量进行了过度预测。少量水的使用在预测的和测量的土壤含水量之间产生最大的分歧。从经验方法估算发射率得出了一个方程,用于预测土壤剖面顶部21 cm处的土壤水分。利用该公式根据经验技术估算的L波段发射率预测的土壤含水量与实测的土壤含水量相比非常好,而与土壤水分剖面或施水量无关。但是,通过经验方法估算的添加到21至150厘米土壤层中的水量与X波段和L波段发射率的变化率之比之间的关系仍然产生了可观的数据分散性。

著录项

  • 作者

    BAUSCH, WALTER CHARLES.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Geological Survey.; Engineering Agricultural.
  • 学位 Ph.D.
  • 年度 1980
  • 页码 185 p.
  • 总页数 185
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农业工程;
  • 关键词

  • 入库时间 2022-08-17 11:51:34

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