Spring-neap variation of total suspended solids over the Changjiang Bank in winter based on GOCI

Total suspended solids concentration (TSS) over the Changjiang Bank exhibits significant spatial heterogeneity and distinct rhythmic variations at spring-neap and quarter-diurnal timescales. However, limited spatial coverage of observations restricts large-area TSS mapping, while insufficient temporal resolution introduces frequency aliasing that obscures spring-neap TSS signatures. Here, we applied spatiotemporal Kriging interpolation to hourly TSS data from the Geostationary Ocean Color Imager (GOCI) to enhance spatial coverage. Subsequently, the daily mean (TSS daily ) and daily range (ΔTSS) of TSS were derived to quantitatively analyze the spatiotemporal evolution of TSS over a spring-neap cycle. Results show that both TSS daily and ΔTSS present a tongue-shaped distribution decreasing southeastward, which can be classified into high-, medium-, and low-turbidity & diurnal-variability zones offshore (denoted as H-, M-, and L-Zones). Notably, the H-Zone displays a stepped pattern aligned with three latitudinal sand dunes near the 40-m isobath. Over the spring-neap cycle, TSS daily and ΔTSS generally co-varied with tidal currents. The H-Zone contracted and gradually lost its stepped pattern as tidal currents weakened, then expanded and reestablished this stepped pattern as tidal currents strengthened. Mechanistic analysis reveals that the spatiotemporal variations in TSS daily and ΔTSS are primarily governed by tide-induced mixing, modulated by water depth and tidal currents velocity. Specifically, water depth determines their distribution patterns, while variations in tidal current velocity drive their spring-neap evolution.