Distribution and variability of sea surface temperature fronts in the south China sea

Abstract

High-resolution satellite observations of sea surface temperature (SST) were used to derive the daily SST fronts and monthly frontal probability (FP) in the South China Sea (SCS). A gradient-based frontal detection method was applied to increase the accuracy for frontal identification. The current study offered a comprehensive description for the variability of SST front and the associated dynamics in the SCS. Large variability was found along the coast of China and Vietnam, northwest of Luzon Island, and the corresponding seasonal cycle captured highest (lowest) values in winter (fall). The wind pattern was found highly influential for frontogenesis. The northeast monsoon in winter drove onshore Ekman transport near the coast of China, which induced convergence between coastal cold water and onshore warm water. The southwest monsoon during summer induced offshore transport, which brought upwelling near the coast of southeast Vietnam and east of Hainan Island. There were fronts generated between cold coastal water and offshore warm water during both monsoon patterns for impacted regions. The integrated effect from intrusion of the Kuroshio Current, wind stress curl and eddy activity were found favorable for generating fronts near Luzon Island. The dynamical relationship was more prominent at anomalous field that higher FP was associated with larger wind stress. And the interannual variability of fronts in the basin was clearly impacted by El Niño related large-scale atmospheric signals.