Collaborative Research: Continued Development of Global Positioning System (GPS) as an Instrument for a Continental-Scale Soil Moisture Network

该项目旨在进一步开发和完善一种从全球定位系统(GPS)接收器中提取近地表土壤湿度估计值的方法，作为一个大陆规模的土壤湿度网络，并评估误差以确定估计值中的潜在不确定性。具体地说，调查员将(A)量化物理环境的不同方面如何影响土壤湿度估计，包括(I)土壤水分和质地的垂直剖面；(Ii)植被数量和结构；(Iii)地形和地表粗糙度，并评估每个地球镜板块边界观测站(PBO)周围的物理环境是否适合使用GPS土壤水分技术；(B)评估天线和接收器设计/性能以及卫星信号如何影响从GPS信噪比(SNR)数据得出的土壤水分时间序列，并评估PBO使用的设备，因为其网络庞大、均匀且维护良好。该项目是水文学家、气候科学家、电气工程师和GPS测地仪的合作项目。将从七个现场站点收集广泛的数据，包括GPS、现场土壤湿度、气象和植被信息。不同的数据类型将使用一个集成的建模系统进行组合，该系统旨在了解物理环境和天线/接收器设计如何影响GPS SNR数据。这将产生一种以物理原理为指导的从GPS SNR数据中反演土壤水分的算法。这项研究将为水文和气候研究以及天气预报提供重要的新的土壤水分数据，从而造福社会。两名研究生将接受包括水文学、遥感和全球定位系统大地测量学在内的跨学科教育项目的支持和培训。

This project aims to further develop and refine a method to extract near-surface soil moisture estimates from Global Positioning System (GPS) receivers as a continental-scale soil moisture network and to evaluate errors to establish the underlying uncertainty in the estimates. Specifically, the investigators will (a) quantify how various aspects of the physical environment influence soil moisture estimates, including (i) vertical profiles of soil moisture and texture; (ii) vegetation amount and structure; and (iii) topography and surface roughness, and evaluate the physical environment around each of the Earthscope Plate Boundary Observatory (PBO) sites for suitability for the GPS soil moisture technique; (b) evaluate how antenna and receiver design/performance and satellite signals influence the soil moisture content time series derived from GPS signal-to-noise ratio (SNR) data, and evaluate the equipment used by PBO because its network is large, homogeneous, and well-maintained.This project is a collaboration between hydrologists, climate scientists, electrical engineers, and GPS geodesists. A broad range of data will be collected from seven field sites, including GPS, in situ soil moisture, meteorological, and vegetation information. The different data types will be combined using an integrated modeling system designed to understand how the physical environment and antenna/receiver design influence GPS SNR data. This will yield a retrieval algorithm for soil moisture from GPS SNR data that is guided by physical principles. This research will benefit society by providing important new soil moisture data for hydrological and climate studies and weather forecasting. Two graduate students will be supported and trained in a interdisciplinary educational program including hydrology, remote sensing, and GPS geodesy.