In this paper, local meteorological data for a period of 35 years (from 1979 to 2013) from Kuujuaq station have been used to calculate the surface refractivity, N (a link for the data is available in the acknowledgements), and to estimate the vertical refractivity gradient, dN1, in the lowest atmospheric layer above the ground. Monthly and yearly variations of the mean of N and dN1 are provided. The values obtained are compared with the corresponding values from the ITU maps. The long‐term trend of the surface refractivity is also investigated. The data demonstrate that the indices N and dN1 are subject to an evolution that may have significance in the context of climate change. Monthly means of N show an increasing departure from ITU‐R values since 1990. Yearly mean values of the dN1 show a progressive decrease over the period of study. Seasonal means of dN1 show a decrease over time, especially for summer. Such a trend may increase the occurrence of superrefraction. However, currently available ITU‐R recommendations for microwave link design assume a stationary climate, so there is a need for a new modeling approach.
In this paper, long-term meteorological data are measured using six fixed surface weather stations and one radiosonde in the subtropical Arabian Gulf region, in particular United Arab Emirates (UAE). The surface refractivity profiles, N s , and refractivity extrapolated to sea level, N o , obtained from surface meteorological data using both fixed and radiosonde stations are investigated and compared. The monthly and cumulative distributions of dry, wet and net components of N s and surface meteorological parameters obtained using both fixed and radiosonde stations are also presented and compared. The obtained results are compared with ITU maps for similar propagation parameters showing non-coherence in some cases.
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