Accurate knowledge of seawater optical properties is essential for underwater imaging, sensing, and optical communication, particularly in coastal and shallow-water environments where geometric light propagation effects can influence measurement accuracy. While empirical formulations describing the refractive index of seawater are well established and widely used in the visible spectral range, their applicability in the near-ultraviolet region has received limited experimental validation. In this work, the applicability of an established empirical seawater refractive-index formulation in the near-ultraviolet band is investigated through a combined numerical and experimental approach. First, the empirical model is evaluated numerically to examine its spectral behavior across the visible–near-ultraviolet transition. The results indicate smooth and physically consistent refractive-index variation near the ultraviolet boundary. Second, a controlled laboratory experiment is conducted in which near-ultraviolet beam refraction through stratified seawater is measured using a multi-compartment tank designed to emulate discrete ocean depth intervals. Beam displacement measurements at two near-ultraviolet wavelength bands are compared directly with predictions obtained from a multi-layer ray-tracing simulation based on the empirical formulation. The close agreement between simulated and experimentally measured beam displacement across multiple depth configurations provides physical validation of the empirical refractive-index model in the near-ultraviolet region under the investigated conditions. These findings support the use of established refractive-index formulations for near-ultraviolet underwater optical modeling and contribute to a more reliable foundation for near-UV marine optical sensing and measurement applications.
Khatibi et al. (Sat,) studied this question.