Antarctic meltwater spread pattern and its duration modulate abyssal circulation

Antarctic meltwater could slow the abyssal circulation, which is essential for ventilating heat, carbon, and nutrients, thereby influencing global climate patterns and marine ecosystems. However, the impact of Antarctic meltwater on abyssal circulation under diverse melting scenarios remains underexplored. Here, we investigate the sensitivity of abyssal circulation to the location, rate, and duration of meltwater input using an Earth system model of intermediate complexity. The horizontal distribution of negative surface ocean density anomalies varies depending on the meltwater input regions and rates, with the circulation weakening most significantly, especially when meltwater effectively spreads into deep convection areas. Furthermore, experiments with different meltwater input rates and durations, while maintaining a constant total amount, suggest that more gradual input has a greater impact on reducing abyssal circulation. These results highlight the importance of both the extent and duration of meltwater influence over deep convection areas in shaping the behavior of abyssal circulation.