+ 'Cross-shelf transport in the Northern South China Sea (NSCS) plays a pivotal role in nutrient exchange and carbon cycling, yet its Lagrangian pathways and dynamic responses to wind forcing remain insufficiently understood. This study employs a high-resolution ROMS hydrodynamic model coupled with a Lagrangian particle-tracking framework to quantitatively investigate the cross-shelf transport of surface particles released during the summer monsoon of June 2020. Simulation results reveal distinct spatial heterogeneity in transport patterns. While the inner shelf is largely constrained by alongshore currents, the widened topography at the eastern shelf acts as a critical offshore "leakage" pathway. In the middle and outer shelves, cross-shelf exchanges are highly active, predominantly driven by entrainment from a western mesoscale cyclonic eddy, forming filamentary structures that transport water beyond the 1000-m isobath. While intensified southwesterly winds are expected to enhance offshore Ekman transport, our results show that they simultaneously suppress eddy-mediated export by modulating the alongshore pressure gradient. Momentum balance analysis reveals the underlying mechanism: strong alongshore winds induce water accumulation on the northeastern shelf, elevating sea level and generating a southwestward (downstream) pressure gradient force. This downstream force disrupts the quasi-geostrophic balance required for particle capture by the western eddy, leading to a net reduction in cross-shelf particle export despite the enhanced wind forcing. Consequently, particles are transported rapidly alongshore under strong winds, whereas weaker winds favor northeastward (upstream) pressure gradients that enhance eddy capture efficiency. This study elucidates the complex interplay between monsoon intensity, shelf topography, and mesoscale eddies, providing critical insights into pollutant residence times and biogeochemical fluxes in marginal seas.',
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