Temporal Variation of the Refractive Index in Coastal Waters

Abstract

Sensors that are dependent on transmission of electromagnetic waves are often subject to anomalous propagation, especially in coastal maritime areas. This anomalous electromagnetic wave propagation can be a problem for radars because the variation of the refractive index can induce loss of radar coverage. The anomalous propagation is due to the variations of the humidity, temperature and pressure that cause variations in the refractive index. The paper presents short time variation of the refractive index over line-of-sight paths of approximately 3 km in mountainous coastal waters using X-band.