Investigation of gps signal amplitude fluctuations depending on meteorological factors when passing through a turbulent atmosphere at low elevation angles over the land

Subject and Purpose. The paper investigates tropospherically caused fluctuations of signals from the GPS navigation system while the satellite is beyond the radio horizon. The intensity of GPS signal fluctuations under the influence of meteorological factors is studied, too. The purpose of the work is to determine relationship between the intensity of GPS signal fluctuations and the meteorological conditions when satellite elevation angles are small. Methods and Methodology. The methodology of the work is based on the search for the intensity of amplitude fluctuations of GPS satellite’s signals depending on the meteorological situation. The measurement approach is registration of the GPS satellite’s signal level just before the satellite crosses the horizon. The data processing after a series of experimental studies is based on the extraction of tropospheric fluctuations from the complete GPS signal by the moving average method. Results. Experimental studies of the turbulent component of signals from GPS satellites at low elevation angles have been carried out. It has been revealed that a conventional elevation boundary below which the tropospheric influence is predominant can be established due to the synchronism property which the orbits of the GPS satellites hold. It has been shown that variations in the mean square deviation (MSD) of GPS signal fluctuations caused by the troposphere and extracted from the complete signal are consistent with meteorological parameter changes. Conclusion. Analysis has been carried out to show that a meteorological dependence of the MSD statistics of GPS signal tropospheric fluctuations exists. The intensity of fluctuations rises with the convective activity in the troposphere. The conducted experiments suggest that periods of increased turbulence in the atmosphere can be detected with the use of GPS signals. For this purpose, the optical methods will not do.