Atmospheric Ducts and Their Electromagnetic Propagation Characteristics in the Northwestern South China Sea

The propagation of electromagnetic waves beyond the line sight can be caused by atmospheric ducts, which are significant concerns in fields radar and communication. This paper utilizes data from seven automatic weather stations five radio-sounding to statistically analyze characteristics ducts northwest region South China Sea (SCS). After verifying practicality numerical analysis NCEP CFSv2 ECMWF studying using measured data, we analyzed spatial–temporal distribution height regional evaporation duct bottom elevated duct. study found that accurately capture occurrence rate area, calculated ERA5 have good consistency. coastal SCS vary significantly month, demonstrating clear monthly patterns; conversely, changes Xisha station minimal, indicating temporal uniformity. For lower difference rates between 00:00 12:00 (UTC) is negligible. probability Beibu Gulf area relatively high, mainly concentrated January April, dominated surface without foundation layers, June August. Monsoons play a critical role generation evolution SCS, with increasing decreasing after onset summer monsoon. In end, simulated loss under different frequencies radiation elevation angles various environments within typical structure.