Experimental analysis of lower atmospheric duct monitoring based on AIS signal

In view of the significant influence of lower atmospheric duct on radar and communication systems at sea, a new method of remote sensing lower atmospheric duct at sea based on measured automatic identification system (AIS) signal is proposed. The propagation characteristics of AIS signal in different atmospheric refraction environments are discussed, and the significant influence of lower atmospheric duct, especially surface duct, on AIS signal operated on VHF band is verified. The plan position distribution results of the received power of shore based AIS receiver on April 20 and 22, 2018 are given. Furthermore, the modified atmospheric refractivity profile of the radiosonde site near the receiving station is used to verify that the lower atmospheric duct is the main reason for the long-range propagation of AIS signal. Finally, the basic procedure of inversion of lower atmospheric duct based on AIS signal is given, and the inversion results based on single azimuth received power using particle swarm optimization algorithm are given. This method has the advantages of passive reception of non-active radiated electromagnetic signals and high temporal and spatial resolution. It is a useful supplement to the current radar sea clutter and satellite navigation signals for remote sensing atmospheric duct.