Collaborative Research: Novel In Situ Measurement and Remote Sensing Techniques for Characterization of Near-Surface Soil Hydrology

覆盖地球表面的最上层土壤控制着重要的过程，包括降雨如何转化为可能导致洪水的径流，以及水如何补充含水层或储存在土壤中以支持植物生长。由于土壤表面特性，包括湿度和温度，在整个土地上并不均匀，而且随时间而变化，因此很难在大范围内测量它们。近年来，卫星遥感已成为近地表土壤性质大规模监测的有力工具。然而，卫星探测到的近地表过程尚不清楚，因为到目前为止，最上层（约一英寸）的土壤很少受到关注。我们缺乏校准卫星观测所需的地面测量技术。为了填补这一知识空白，并为卫星测量校准提供关键数据，该项目将开发新型传感器阵列和数学模型，能够测量和描述土壤顶部一英寸内的湿度和温度变化。这项技术将通过配备新型传感器和特殊遥感相机的大直径精密称重土柱进行测试和改进。考虑到气候变化，特别是美国干旱和半干旱地区的气候变化，该项目将为管理我们宝贵的水和环境资源提供宝贵的信息和工具，并改善相关科学学科的研究。地球表面经历着极端的时空湿度和温度变化，并控制着重要的水文过程，如入渗、径流和蒸发。卫星遥感（RS）是表征和监测地球表面过程的有力工具，但由于缺乏高分辨率校准技术，人们对电磁波穿透深度内的近地表（NS）动力学知之甚少。本研究解决了改善NS土壤性质和过程动力学监测的关键需求。该项目的目标是：1)开发和采用新的原位测量技术；2)评价和推进RS理论在NS土壤水分估算中的应用；3)开发和测试用于土壤水力特性测定的创造性RS算法。为了实现这一目标，将利用高分辨率时域反射阵列（TDRA）和五针热脉冲探针阵列（PHPPA）等仪器测定地面NS的水分含量、温度、热性质以及土壤热量和蒸发通量。这些NS测量将与土壤湿度估算的分析解决方案相结合。将使用标度法和土壤表面湿度和温度的RS从第一阶段蒸发的持续时间来估计土壤的水力特性。所提出的概念将在亚利桑那大学用一对4米深× 2.4米直径的精密称重溶锡仪进行测试，该计配有热成像和短波红外摄像机。该项目将改变陆地和水文模型的校准和预测能力，并在考虑到气候变化的情况下，特别是在美国和全球的干旱和半干旱地区，为管理地球宝贵的环境资源提供有价值的信息。高分辨率近地表物理和水文测量能力（TDRA和PHPPA）的发展也将提高相关科学学科（如生态水文学和大气科学）的研究能力。

The uppermost soil layer that covers the Earth's surface controls important processes, including how rainfall turns into runoff that can cause flooding and how water that recharges aquifers or is stored in the soil to support plant growth. Because soil surface properties, including moisture and temperature are not uniform across the land and vary with time, it is difficult to measure them over large areas. Recently, satellite remote sensing has become a powerful tool for large-scale monitoring of near-surface soil properties. However, the near-surface processes sensed by the satellites are poorly understood because the top layer (about one inch) of soil has received little attention until now. We lack the ground-based measurement technology needed to calibrate satellite observations. To fill this knowledge gap and to provide crucial data for calibration of satellite measurements, this project will develop of novel sensor arrays and mathematical models capable of measuring and describing moisture and temperature variations within the top inch of soil. This technology will be tested and refined with large diameter precision-weighing soil columns instrumented with the new sensors and special remote sensing cameras. The project will provide invaluable information and tools for managing our precious water and environmental resources in view of climate variability, especially in arid and semiarid regions of the USA, and improve research in related scientific disciplines. The Earth's surface experiences extreme spatiotemporal moisture and temperature variations and controls important hydrological processes such as infiltration, runoff, and evaporation. Satellite remote-sensing (RS) is a powerful tool for characterization and monitoring of Earth surface processes, but near-surface (NS) dynamics within the penetration depth of electromagnetic waves are poorly understood due to a lack of high-resolution calibration techniques. This research addresses the crucial need for improved monitoring of NS soil property and process dynamics. The project objectives are to: 1) develop and employ novel in situ measurement techniques; 2) evaluate and advance RS theory for NS soil moisture estimation; and 3) develop and test creative RS algorithms for soil hydraulic property determination. To achieve the objectives, ground-based NS moisture content, temperature, thermal properties and soil heat and evaporative fluxes will be determined with instruments including a high-resolution time domain reflectometry array (TDRA) and a penta-needle heat pulse probe array (PHPPA). These NS measurements will be coupled with analytical solutions for soil moisture estimates. A scaling method and RS of the soil surface moisture and temperature will be used to estimate soil hydraulic properties from the duration of Stage 1 evaporation. The proposed concepts will be tested with a pair of 4-m deep x 2.4-m diameter precision weighing lysimeters at the University of Arizona, instrumented with thermal imaging- and shortwave IR-cameras. The proposed project will transform calibration and predictive capabilities of land-surface and hydrologic models and provide valuable information for the management of Earth's precious environmental resources in view of climate variability, especially in arid and semiarid regions of the US and globally. The development of high-resolution near-surface physical and hydrologic measurement capabilities (TDRA and PHPPA) will also enhance research capabilities of related scientific disciplines (e.g., ecohydrology and atmospheric science).