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径流导致洪水，以及如何补给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，包括水分和温度，在整个土地上并不均匀，并且随着时间的变化而变化，因此很难在大范围内测量它们。近年来，卫星遥感已成为大规模监测近地表土壤性质的有力工具。然而，卫星探测到的近地表过程知之甚少，因为到目前为止，最上层(约一英寸)的土壤几乎没有受到关注。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，并为卫星测量的校准提供关键数据，该项目将开发能够测量和描述土壤表层水分和温度变化的新型传感器阵列和数学模型。这项技术将通过大直径精密称量土柱进行测试和改进，这些土柱配备了新的传感器和特殊的遥感相机。鉴于气候变化，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，并促进相关科学学科的研究。地球表面经历了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。卫星遥感是描述和监测地球表面过程的有力工具，但由于缺乏高分辨率的定标技术，人们对电磁波穿透深度内的近地表动力学了解很少。这项研究解决了改善NS土壤性质和过程动力学监测的迫切需要。该项目的目标是：1)开发和应用新的现场测量技术；2)评估和推进RS理论用于NS土壤水分估计；3)开发和测试创新的RS算法来确定土壤水力性质。为了实现这些目标，地面NS水分、温度、热物性以及土壤热量和蒸发通量将使用包括高分辨率时域反射仪阵列(TDRA)和五针热脉冲探头阵列(PHPPA)在内的仪器来确定。这些NS测量将与土壤水分估计的分析解决方案相结合。根据第一阶段蒸发的持续时间，将使用土壤表面水分和温度的标度方法和遥感来估计土壤水力特性。亚利桑那大学的一对4米深x 2.4米直径的精密称重蒸渗仪将测试拟议的概念，该仪器配备了热成像和短波红外相机。拟议的项目将改变陆面和水文模型的校准和预测能力，并鉴于气候变化，特别是在美国和全球干旱和半干旱地区，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)的发展也将加强相关科学学科(例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).