Ch 34. GNSS Reflectometry for Earth Remote Sensing

Overview:

Reflectometry is one of many new applications made possible by freely available global navigation satellite system (GNSS) signals. Services provided by reflectometry are quite removed from those of position, navigation, and timing (PNT) and were never envisioned in the formulation and design of GNSS. Nonetheless, key properties of a signal design optimized for PNT enable new types of measurements that provide important societal benefits. Much like radio occultation (Chapter 33), reflectometry can be used to infer properties of the propagation environment by observing changes in the GNSS signal resulting from its interaction with that environment.

Following a brief history of the field, we will describe the fundamental principles and basic observables used in GNSS‐R. This will be followed by applicable scattering models and their numerical evaluation. The remainder of this chapter will introduce a number of examples of important applications. Additional details on retrieval methods and models relevant to each specific measurement will be provided in the corresponding subsections.