Seasonal variation of geoclimatic factor in terrestrial wireless link design

Microwave telecommunications links are severely influenced by the frequency and climatic parameters as refractivity gradient (dN1), geoclimatic factor (K), rain, temperature, pressure, and humidity. This influence increases with the frequency of the wave. In microwave band, recent research has shown that the geoclimatic factor (K), rain and temperature are the most important parameters affecting the performance of terrestrial links. K is an important parameter as directly proportional to the worst month outage probability P_w. K depends on the refractivity gradient dN1. The dN1 depends itself on the pressure, the temperature and the humidity. In this paper, we demonstrated from the data of the terrestrial links located in Quebec, Canada, that there is a seasonal variation of the geoclimatic factor, K_mes. This variation of K_mes is mainly due to the variation of the humidity. The variation of the geoclimatic factor is not limited to the seasonal variation. But it is true from one year to another. IUT recommendations do not embed climate change, but assume a stationary climate. We recommend to improve data analysis and predictive models by taking into account the temporal changes.