Analysis the Influence of a Mesoscale Cold Eddy on Underwater Sound Propagation in the East of Luzon Strait

Abstract

1Based on the data of Argo float, satellite altimeter merged data, and HYCOM model output, we analyzed the temporal-spatial variations of a mesoscale cold eddy in the east of Luzon Strait, and used FOR3D model to simulate the effects of this mesoscale cold eddy on sound propagation, Calculated out the transmission loss(TL) with or without the cold eddy. Result show that the presence of cold eddy led to significant variation of sound propagation. Typically, the distances of convergence zones were narrowed several kilometers, and the gain of convergence zones were inhibited about 2 dB.

Response of sound propagation characteristics to Luzon cold eddy coupled with tide in the Northern South China Sea

“…This shift is attributed to the lower temperature around the core of the cold eddy, which increases the refraction of rays towards this region. The conclusion is consistent with the results of previous studies (Jian et al, 2009;Li et al, 2011;Ruan et al, 2019;Xiao et al, 2019;Chen et al, 2019;Zhang et al, 2020). However, when the source depth is 800 m (Figures 8C, D, deep-sea channel propagation), the shift decreases to 3 km in section A, while almost reaches 15 km on section B, which can be explained in two ways.…”

“…Recently, more attention has been paid to analyzing sound propagation in three-dimensional baroclinic ocean simulations using dynamic models, as opposed to theoretical models. Regarding the influence of eddies on sound propagation, Ruan et al (2019) utilized the FOR3D model to investigate the impact of a cold eddy in the Luzon Strait on the convergence zone of the sound field based on the 3-D temperature and salinity fields output from the HYCOM model. Hassantabar et al (2021) used high-resolution ROMS and the BELLHOP model to discuss the effect on sound propagation by Mediterranean eddies during different periods.…”