Estimation of subrefraction statistics using surface synoptic meteorological data

A companion paper developed a subrefractive fading model, in terms of a minimum effective
k
value, using surface synoptic meteorological data. The concept is extended here to cover the whole subrefractive event, so that using the effective
k
parameter
k_{e}
, analog radio systems can be simply designed. In the case of digital systems, severe subrefraction may cause outages due to thermal noise increase and this effect must be considered in design. For plains paths, where subrefraction risks are greatest, a method of estimating the shape of the
k_{e}
versus time curve of individual events by using correlations with surface synoptic meteorlogical data is given. By summation of time below each selected
k_{e}
value enables statistics of
k_{e}
to be produced. Examples of the method are given, and it is shown how regions of subrefraction may be defined.