Impact of Evaporation Duct on Electromagnetic Wave Propagation During a Typhoon

The evaporation duct, a result of evaporation from the ocean, is a region above the sea surface in which radio waves are refracted downward. This duct has strong effects on microwave instruments. Typhoons cause huge anomalies in marine meteorological parameters that influence the evaporation duct distribution and structure, which in turn affects the propagation of electromagnetic (EM) waves. However, EM wave propagation under the typhoon process has seldom been reported. Thus, taking Typhoon Phanfone (201929) as an example, this study uses a dataset from the European Centre for Medium-Range Weather Forecasts, combined with the Naval Atmospheric Vertical Surface Layer Model and the parabolic equation model, to study the evaporation duct’s impact on EM wave propagation during a typhoon. The spatial and temporal path loss distributions reveal that large amounts of EM wave energy are emitted from the evaporation duct when the EM wave passes through a typhoon eye. On average, a typhoon eye causes an approximately 20 dB increase in path loss for EM wave propagation at low antenna height. Furthermore, the effects of a typhoon eye on EM wave propagation at different signal frequencies and antenna heights are studied. The results show that a typhoon has a larger impact on EM wave propagation with low signal frequency and high antenna height.