Sedimentary  U37K′ ${\mathbf{U}}_{\mathbf{37}}^{\mathbf{K}\prime }$ in the South China Sea Reflects Mean Sea Surface Temperatures Despite Substantial Winter Monsoon‐Driven Alkenone Flux Variability

Abstract The alkenone‐based index is widely used to reconstruct sea surface temperature (SST), including past SST variability associated with the East Asian Winter Monsoon (EAWM). However, its ability to record and preserve seasonal signals remains uncertain. Here, we present alkenone flux and temperature data from two sediment traps in the oligotrophic northern South China Sea (SCS). The records show dampened seasonal variability and temporal lags compared to the weekly SST record, resembling time‐averaged SST over 20–40 weeks, which indicates long residence times of alkenones. High temperatures during winter suggest that the winter flux contains material produced outside of winter and/or transported from adjacent continental shelf. Consequently, flux‐weighted temperatures align closely with annual mean SSTs, despite elevated alkenone flux during the EAWM months. These findings suggest that ‐based reconstructions in the northern SCS likely reflect annual mean condition rather than EAWM variability.