On horizontal distribution of vertical gradient of atmospheric refractivity

The horizontal distribution of the vertical gradient of atmospheric refractivity is important for the assessment of the propagation of electromagnetic waves on nearly horizontal paths. A 5‐year set of meteorological data, obtained from the ERA‐Interim numerical weather product, has been used to analyze this distribution statistically. Vertical gradient maps of the Central European region have been processed to derive empirical probability distributions of the difference between local point gradient values at two locations. The difference of the effective (path‐averaged) gradient along the path and the local gradient is shown to be statistically distributed so that the quantiles increase linearly with distance in the interval from 100 to 1000 km. Finally, a spatial correlation function is obtained and described by an exponential model with correlation distances determined in the range of 400–700 km. The horizontal distribution of the vertical gradient of atmospheric refractivity is analyzed statistically using 5‐year meteorological data obtained from the numerical weather product ERA‐Interim. The spatial correlation function is obtained and described by an exponential model with correlation distances determined in the range of about 400–700 km.