Seasonal frontal variability and stratification coupling from 2022 CTD observations in the southern coastal waters of Korea
Year: 2025
Type: article
Abstract: Introduction Using May–November 2022 CTD observations from the central–eastern southern coastal waters of Korea, we quantified the variability of oceanic fronts and their coupling with water-column stability. Methods We used conventional | ∇ T | , | ∇ S | thresholds and a composite Integrated Frontal Index (IFI) of | ∇ T | , | ∇ S | , and N²; the stability effect is Δ IFI = I F I T S N 2 - I F I T S . Results Fronts were coherently organized along the coastal–offshore boundary zones near the 70–100 m isobaths. Their intensity and principal formation depths reflected seasonal stratification and thermocline–halocline alignment (ΔTHD ): fronts were sharp and continuous when the clines co-occurred in summer, but diffuse and deeper when offset during autumnal cooling and mixing. Quantitatively, in the upper layer (10–30 m) the IFI closely co-locates with salinity fronts (≈99–100%) and also with temperature fronts (~87–93%), whereas agreement declines and becomes more variable below about 40–50 m. ΔIFI exhibited a depth-dependent pattern (mean −5.7 at 10 m, −1.3 at 60 m, −4.6 at 80 m), consistent with surface weakening, mid-layer mitigation, and renewed deep weakening. Discussion The framework captures transitions between salinity- and temperature-dominated regimes and quantifies the amplification–weakening mechanism associated with ΔTHD , providing an observation-based diagnostic for front–stratification coupling.
Source: Frontiers in Marine Science
Authors: Baekjin Kim, Seonghyeon Kim, Soonyeol Kwon, Sunjong Lee, Eung Kim
Institution: Korea Institute of Ocean Science and Technology
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,801
OpenAlex ID: W4416384208