A novel mathematical model for complex humidity profile variation with elevation

Free space propagation of communication signals under anomalous weather conditions is unpredicted and may result in very strong signals at certain locations and almost complete blackout at others. This is due to the abnormal refractive index prevailing in the area as a result of the variation of the humidity levels with altitude. In this paper, existing models describing the variations of the humidity profile with altitude which are crucial in predicting the signal strength in space are presented and discussed. It is shown that these models cannot properly describe complex profiles such as those prevailing in high humidity areas like the Caribbean or the Arabian Gulf area. A new mathematical model is suggested to meet the needs for such complex profiles and it is shown that this new model is capable of representing any natural humidity profile accurately without creating false inversion layers as is the case with other models. The new model is applied to the problem of space wave propagation and locations of field strength and weakness are identified.