Vertical profiling of atmospheric refractivity from ground-based GPS

We estimate refractivity structure near San Diego, California, using ray propagation models to fit measured GPS tropospheric delays in a least squares metric. We evaluate the potential and the limitations of ground-based GPS measurements for characterizing atmospheric refractivity, and we compare refractivity structure estimated from GPS sensing with that measured by nearby radiosondes.

The results suggest that ground-based GPS provides significant constraint of inhomogeneous atmospheric refractivity, despite certain fundamental limitations of ground-based measurements. Radiosondes typically are launched just a few times daily. Consequently, estimates of temporally and spatially varying refractivity that assimilate GPS delays could substantially improve over estimates using radiosonde data alone.