Comparison of evaporation duct and path loss models


  • Wayne L. Patterson


This paper will evaluate the current meteorological measurement techniques used to infer the evaporation-ducting process. Included within this study is a comparison of relative performance, sensitivities to meteorological inputs, and ease of computation for three standard evaporation duct models and two electromagnetic wave propagation models. The evaporation duct models performed reasonably and equally well when considering statistically averaged meteorological inputs, but all were extremely sensitive to point-observed meteorological input parameters. The measurement techniques employed by naval and transiting commercial vessels are not of sufficient quality to infer adequately the evaporation-ducting process. The theory behind calculation of path loss values based upon current evaporation duct inputs is statistically sound. For studies of propagation phenomena or development of electromagnetic systems, both of the compared models perform reasonably well and are accurate predictors. However, the use of either model for estimation of a single propagation range based upon a point meteorological observation is severely limited by the accuracy of the data.