Influences of Inhomogeneous Spatial Distribution of Global Oceanic Atmospheric Refractivity on LF Groundwave Propagation Delay

Atmospheric refractivity affects the propagation delay of low-frequency (LF) groundwave in the realistic ocean environment. In this paper, a parabolic equation (PE) model based on the ERA5 meteorological reanalysis dataset is applied to analyze the influences of inhomogeneous spatial distribution of global oceanic atmospheric refractivity on LF groundwave propagation delay. The global oceanic atmospheric refractivity is derived from the meteorological quantities given by the ERA5 reanalysis dataset. It is found that the global oceanic surface atmospheric refractivity varies systematically with latitude in the range of 290~300 N-unit to 380~400 N-unit, which in turn leads to the variation of LF groundwave propagation delay reaching hundredth nanosecond for 1000 km-long propagation path.