Estimation of Tropospheric Fluctuations Using GPS Data

This article reports on a method of extracting tropospheric turbulence statistics from the Global Positioning System (GPS) Flinn database. The elevation and site dependence of the GPS residuals are shown to agree with the expectations of troposphere delay fluctuations. The GPS residuals are shown to have temporal statistics that are consistent with the assumed turbulence model. The turbulence parameter, Cn, is extracted from the GPS residuals and is found to be consistent with both water vapor radiometer and very long baseline interferometry measurements. Seasonal and diurnal variations in Cn were observed to be consistent with other measurements and compared well with a simple wet refractivity model. This technique for obtaining Cn from GPS data may be useful for several classes of Ka-band (32-GHz) radio science experiments, as they will be limited by tropospheric phase fluctuations.