GLORI airborne campaigns

Global navigation satellite system (GNSS) reflectometry has recently emerged as a promising remote sensing tool for the retrieval of several geophysical parameters characterizing continental land surfaces (soil moisture, vegetation water content, biomass). When GNSS-reflected signals are recorded and processed by an airborne receiver, they can be interpreted in the form of delay correlation waveforms or delay Doppler maps (DDMs).

In 2013, a new polarimetric GNSS-R system, referred to as the GLORI receiver, is developed by CESBIO. This system was installed on SAFIRE French ATR42 research aircraft. Following initial laboratory qualifications, two airborne campaigns involving 9 flights were carried out in 2014 and 2015 in the South West of France, over various types of land cover, including agricultural fields and forest.

The 2014 campaign demonstrated the viability of the instrument's concept and certified GLORI for use in the SAFIRE ATR-42 research aircraft. In the case of the 2015 campaign, four different test sites were selected for the acquisition of GLORI data over land. Flights were coordinated with in situ ground truth campaigns. Various in situ measurements were made on these sites (vegetation biomass, roughness, soil moisture, and leaf area index), in order to validate the GLORI data, to improve the direct bi-static models, and finally to optimise the inversion algorithms.