An evaluation of the expression of the atmospheric refractivity for GPS signals

摘要: [1] An expression is derived from first principles for the refractivity of air at L band frequencies, which includes GPS, as well other GNSS satellite radionavigation signals. Under conditions pressure, temperature, and moisture content found in Earth's atmosphere, has an average relative error approximately 0.01%. This level accuracy required to guarantee that does not introduce bias, when it used within context Numerical Weather Prediction (NWP) applications. The thermodynamic dependences air's N are revisited, possible sources uncertainty analyzed. A microphysical model constructed, relates frequencies with several measurable properties matter. experimental values critical this purpose already available literature high accuracy. Based on model, a simple suitable atmospheric weather applications proposed: ≡ (n − 1) · 106 = N0 (1 + N0) where (222.682 0.069 τ) ρd (6701.605 6385.886 ρw densities dry water vapor (kg/m3), τ 273.15/T 1, T absolute temperature K. dependence coefficients respect input physical parameters Given parameters, concluded proposed improves meet needs NWP