Two Decades of Ocean Color and Thermal Front Variability in the Chinese Coastal Ocean

Abstract Ocean fronts are critical oceanographic features with significant ecological implications, yet comprehensive multi‐parameter frontal analyses remain limited for Chinese Continental Shelf Seas (CSS) due to insufficient remote sensing data quality and temporal coverage. To address this gap, we developed and analyzed a 20‐year frontal data set derived from MODIS imagery for three key parameters: the absorption coefficients of detritus and colored dissolved organic matter (a dg (443)), phytoplankton (a ph (443)), and sea surface temperature (SST) across Chinese CSS. Our findings suggested that different frontal types may be driven by distinct mechanisms: ocean color fronts are potentially associated with tidal mixing processes, whereas SST fronts are influenced by tidal mixing as well as the convergence of different water masses. Spatially, the two ocean color indicators showed remarkable alignment along isobaths in nearshore regions, indicating consistent hydrodynamic controls. Temporal analysis revealed significant declining trends in ocean color front gradient magnitude (FGM) (−1.15% yr −1 for a dg , −0.68% yr −1 for a ph , respectively), potentially attributed to regional warming and weakening wind speeds. In contrast, SST fronts exhibited winter intensification in high FGM regions, reflecting the spatial heterogeneity of temperature change patterns across water masses. These findings advanced our understanding of frontal variability and climate responses in Chinese CSS, providing insights for marine ecosystem management and climate impact assessment.