Spatial and temporal distributions of evaporation ducts in the Black Sea and their impact on the over-the-horizon propagation of electromagnetic waves

The evaporation duct is a critical factor in maritime electromagnetic wave propagation. It exhibits significant spatiotemporal variability influenced by regional meteorological dynamics. While existing studies have explored evaporation ducts in various regions, the Black Sea is a strategic maritime zone with complex land-sea interactions and remains underexamined. This study presents a integration of the ERA5 reanalysis dataset, the Navy Atmospheric Vertical Surface Layer Model (NAVSLaM), and the Advanced Propagation Model (APM) to systematically characterize evaporation duct height (EDH) distributions in the Black Sea and quantify their impact on over-the-horizon propagation. Leveraging the ERA5 reanalysis dataset for the whole year of 2022, we reveal pronounced north-south EDH gradients: northern regions exhibit seasonal peaks in spring and summer (mean EDH 14.51 m, exceeding annual averages by 2.69 m) driven by lower relative humidity (67.68%), while southern regions show muted seasonality due to higher humidity (72.57%). This study demonstrates that varying evaporation duct conditions induce path loss fluctuations exceeding 100 dB, critically altering radar detection ranges. These findings provide the first comprehensive EDH climatology for the Black Sea and establish actionable insights for optimizing maritime communication and radar systems in evaporation duct-prone environments.