The Xiamen Symposium on Marine Environmental Sciences (XMAS 2027)

How surface wind forcing affects abyssal circulation remains poorly understood, particularly in basins where complex topography strongly constrains deep pathways. Here, we examine the role of topography in linking wind-driven pressure variability to deep transport in two contrasting settings: the Luzon Strait deep overflow and the lower limb of the Atlantic Meridional Overturning Circulation.

In the Luzon Strait, the seasonal cycle of the deep overflow is closely related to the meridional bottom-pressure difference across the strait. Variations in this pressure gradient are associated with wind forcing over both the South China Sea and the upstream western Pacific. Rather than acting as a passive boundary, the surrounding topography organizes the pressure response and constrains the pathways through which the wind-forced signal reaches the deep strait. In the North Atlantic, the seasonal variability of the lower overturning limb also follows bathymetrically constrained pathways, with major ridges, continental slopes, and deep basins shaping the spatial structure of the response.

Together, these results suggest that the influence of surface winds on abyssal circulation depends not only on the forcing itself, but also on how topography regulates pressure adjustment and deep transport pathways. This perspective helps connect regional deep overflows and basin-scale overturning variability, and highlights the importance of topographic structure in interpreting deep-ocean observations and model simulations.