利用SNR观测值进行GPS土壤湿度监测

利用GPS信噪比(SNR)观测值监测土壤湿度变化可克服传统手段破坏观测对象、数据难以同化、时空分辨率受限等缺点,但同时也存在测量区域不明确、卫星与波段选择缺少相应依据、多径延迟相位与土壤湿度之间相关性的定量数值描述函数与模型亟待建立等问题。本文通过引入菲涅尔反射区域,结合仿真和实测土壤湿度数据、GPS观测值开展对比实验对上述问题进行研究。实验过程及结果表明,采用SNR观测值能有效跟踪土壤湿度的变化趋势,最大有效测量范围约45m,利用指数函数能较好地描述SNR多径延迟相位与土壤湿度之间的关系。同时,选择高级卫星和记录L2C观测值,有利于获得更准确的结果。

Comparative Experiments on Soil Moisture Monitoring with GPS SNR Observations

Using the SNR observations from geodetic UPS receiver to monitoring the soil moisture is a new method，which does not suffer from destruction of observed soils，difficult data assimilation and time-spatial resolution limits. However，there are issues need to be solved such as uncertain measuring area，selection rules of parameter as wavelength and satellites，and construction of relationshipmodel between the relative delay phase and soil water content. To solve these problems，the Fresnel zone theory is introduced，and two comparative experiments based on simulated and measured soil moisture are carried out. The process and results of experiments show that the remarkable correlation，which can be described well by exponential function，does exist between the relative delay phase and soil moisture. The maximal effective monitoring distance is within about 45 meters. Meanwhile，selection of an advanced satellites and recording of L2C can increasingly improve the quality of SNR and lead to more reliable results.