543 / 2024-09-18 11:16:53

Formation of Dense Shelf Water and Its Effect on Particle Transport Under Different Wind Conditions in the Terra Nova Bay Polynya

Dense shelf water,Particulate organic carbon,Lagrangian particle tracking

The Terra Nova Bay Polynya (TNBP) in the western Ross Sea is a key site for the formation of dense shelf water (DSW) and notable net community production, making this area a significant atmospheric CO₂ sink and particulate organic carbon (POC) source. Sea ice formation and the associated brine rejection, mechanically driven by offshore katabatic winds, cause the DSW to descend along the continental slope and produce the Antarctic Bottom Water (AABW), which transports POC from surface waters and sequesters it in the deep ocean. In this study, we selected 5 strong wind and weak wind events over the TNBP in the freezing season to investigate the influence of offshore katabatic winds with varying intensities on the formation of DSW and its effect on the vertical sinking and transport of particles. A high-resolution coupled ocean-sea ice-ice shelf model is used to conduct Lagrangian particle tracking experiments in order to simulate the transport of POC. During the strong wind events, the formation of DSW increased, enabling POC to be carried from surface to 800 m in approximately 3 days. In contrast, during weak wind events, the formation of DSW is reduced, extending the time required for POC to reach the bottom to over one week or even much longer. There is a significant positive correlation between the zonal wind speed and the maximum particle sinking depth over a seven-day period.