Characterizing atmospheric turbulence with GPS

Atmospheric constituents delay the signals of the Global Positioning System (GPS). Because of their high precision, GPS carrier phase observations are sensitive to temporal fluctuations in these propagation delays. Most of these fluctuations are caused by atmospheric water vapor. Water vapor can therefore indirectly be used as a tracer to characterize atmospheric turbulence. We have developed a new approach for analyzing the delays based on a stochastic model for the fluctuations of the atmospheric refractive index. The turbulence strength can be determined applying least-squares variance component estimation techniques to the phase observations from a single geodetic GPS receiver. Preliminary computations indicate that this new approach is very promising. We present our method and discuss the results and the implications for turbulence measurement.