Development and validation of comprehensive closed formulas for
atmospheric delay and altimetry correction in ground-based GNSS-R
Abstract
Radio wave propagation involved in Global Navigation Satellite System
Reflectometry (GNSS-R) is subject to atmospheric refraction. Even for
ground-based tracking stations, in applications such as coastal
sea-level altimetry, the interferometric or reflection-minus-direct
effect might be significant. Although atmospheric propagation delays are
best investigated numerically via raytracing, including reflections,
such a procedure is not trivial. We have developed simpler closed
formulas to account for atmospheric refraction in ground-based GNSS-R,
validated against independent raytracing. We provide specific
expressions for the two components of the atmospheric interferometric
delay and corresponding altimetry correction components, parameterized
in terms of refractivity and bending angle. Assessment results showed
excellent agreement for both components. We define the interferometric
slant factor used to map interferometric zenithal delays to individual
satellites.