An Investigation of LF Groundwave Propagation Characteristics Over Sea Covered by Ice Using the Parabolic Equation Method

The parabolic equation (PE) method is applied to investigate the amplitude and phase characteristics of low-frequency (LF) groundwave propagation over sea covered by ice. The “ice-sea” stratified medium is characterized by the effective surface impedance of a two-layer half-space model in the PE. Calculations performed for four ice thicknesses (0, 1, 2, 3 m) show that the ice surface of sea significantly affects the propagation of LF groundwave, especially for phase. Also, as the ice thickness increases from 0 to 3 m, the secondary time delay of LF groundwave increases up to 189 ns at a range of 200 km due to the more inductive effective surface impedance for the thicker ice. This indicates that to achieve higher maritime position, navigation, and timing (PNT) accuracy of LF radio navigation systems, the time delay caused by the ice surface of sea should be properly mitigated.