The possibility of exploiting satellite navigation and communication signals for remote sensing applications has been the object of extensive scientific research. Over the last few years, the potential of this technique has been mainly investigated for the observation of the ocean and land, resulting in new space missions, currently in orbit or under study.

The use of signals transmitted by Global Navigation Satellite Systems (GNSS) in L-band as well as transmission of communication signals in P-band have attracted significant scientific and industrial interest, especially for land applications.

The possibility of retrieving soil moisture, vegetation biomass, or monitoring the freeze/thaw state, inundations and snow, by means of GNSS reflections, has recently been confirmed through the analysis of ground-based data, airborne measurements, and technology demonstration missions. In this frame, several research groups are involved in studies based on the exploitation of data produced by the NASA CyGNSS mission, which is currently operational.

Even if all these campaigns significantly contributed to consolidating the physics that is behind the interaction between navigation signals and the bio-geophysical parameters of the illuminated surface, a complete understanding of data needs further scientific efforts, especially for satellite observations.

The session is focused on the recent advances made in GNSS-R and other Signals of Opportunity remote sensing, to give detailed pictures about both the state of the art of modeling activities, of retrieval approaches, and of other applications. Specifically, this session seeks contributions presenting: 1) improved understanding of GNSS-R and other Signals of Opportunity forward models for different types of surfaces; 2) Inverse methods for the retrieval of parameters from GNSS-R and SoOp observations; 3) results from field experiments and satellite data.