Synthesizing Spatiotemporal Structures of the North Atlantic Tripole

Abstract

The interannual-to-decadal variability of sea surface temperature and height in the North Atlantic exhibits a tripolar pattern. Here, we explore the spatiotemporal structure, including the vertical, of the North Atlantic tripole using observations and reanalysis data in 1993–2021. For the first time, we demonstrate that the tripole's vertical structure across the Mid-Atlantic Bight continental shelf and slope differs from that in the ocean interior. The tripole strongly projects in the Slope Water north of the Gulf Stream mean path, marked with temperature changes across the water column not maintained by air-sea heat flux. Over the shelf, the tripole-associated sea level, temperature, and ocean current are weak. In the ocean interior, the tripole temperature variability is apparent in the upper 100 m in the tropics and three times as deep in the subtropics. The tripole imprints resemble those of the North Atlantic Oscillation, peaking after the dominant atmospheric mode's winter maximum.