Determination of the effective earth radius factor and its impact on propagation of signals on over-sea paths in the English Channel

The propagation of radio signals within the troposphere is influenced by the value of effective earth radius factor k, which is dependent on the lapse rate of refractivity in the lowest 1 km of atmosphere. One year of reliable, local radiosonde data, from June 2009 to July 2010, has been used to determine the values of effective earth radius factor k in the English Channel. The cumulative distributions of the values of k as well as the median/mean values of k from different radiosonde stations are presented. The seasonal trend in the variation of k-factor matches the seasonal variation of 2 GHz and 240 MHz signals received over two radio paths in the English Channel.