机载GPS反射信号土壤湿度测量技术

Soil moisture determination of reflected GPS signals from aircraft platform

随着全球导航定位系统反射信号(GNSS-R)技术的发展,近年来提出了利用GPS地表反射信号遥感土壤湿度的新方法,该方法利用地表反射率与土壤介电常数以及介电常数与土壤湿度之间的关系来建立反演模型。为了可以快速方便的利用DMR实测数据反演得到土壤湿度,本文根据Wang和Schmugge模型建立了土壤介电常数与湿度之间的分段模型,实现了从原始反射数据到土壤湿度结果的整个反演流程。为了验证反演的可行性,利用NASA等机构联合进行的SMEX02试验机载数据反演得到的结果表明,GPS反射信号能够有效地反演土壤湿度。最后,提出了改善反演准确度需要考虑的几个问题。

Timely and accurate measurement of soil moisture and its fluctuation is of paramount significance in understanding the global water cycle and improving the weather forecast pattern. With the development of GNSS-R technology, the use of GPS signals reflected from the earth has been proposed as an alternative method to remotely sense soil moisture. Inversion model is established from the truth that the reflectivity is a function of soil dielectric constant which relates to the soil moisture. In order to determine soil moisture from collected data by DMR （Delay Mapping Receiver） fleetly, the whole retrieval flow is processed from original reflected data to soil moisture. In this study, a piecewise model is presented between soil dielectric constant and soil moisture. In order to test the feasibility, the SMEX02 experimental data on aircraft platform taken by NASA was used. The result shows the reflected GPS signal is sensitive to the surface soil moisture.