Modeling and Measurement of Ducted EM Propagation over the Gulf Stream

The study of atmospheric refractive conditions is essential in the shipboard radars and radio communication conditions in the maritime environment. Especially at low altitudes, as radio refractivity can vary considerably with both height and range, characterizing marine atmospheric boundary layer properties, ducting in particular, is thus crucial for air-sea interaction research. The numerical weather prediction model Navy Atmospheric Vertical Surface Layer Model (NAVSLaM) is used to estimate the refractive structure of the evaporation duct as a function of height and range using the environmental conditions in the region of the Gulf Stream, and the refractive profiles are used as input to Advanced Propagation Model (APM) for predicting the EM propagation across the Gulf Stream boundary. The data measured during the CASPER-East at-sea experimental campaign, which was conducted off the coast of Duck, NC, during October-November of 2015, are compared with the simulated propagation loss based on the range-dependent profile predicted from NAVSLaM.