The Beaufort Gyre's Diffusive Staircase: Finescale Signatures of Gyre‐Scale Transport.

Arctic Ocean waters sourced from the Atlantic contain a vast amount of heat. In the Arctic's Beaufort Gyre, diffusive convection is the primary mechanism by which this heat is transported vertically. This mixing process is characterized by a "staircase" where convective layers are separated by interfaces in temperature and salinity. It is not well‐understood what governs layer thickness, which is an important parameter in heat transport. Here we relate staircase properties to the background water‐mass structure of the Beaufort Gyre via analysis of Ice‐Tethered Profiler observations. We find that staircase layer thicknesses vary with intrusive features below the staircase and the stratification overlying the staircase. We relate these features to the pathway of anomalously warm Atlantic Water in the Beaufort Gyre. Results suggest that intrusive features in context with the Gyre's large‐scale geostrophic flow may be key to understanding layer thicknesses and the propagation of warm waters into the Gyre. Plain Language Summary: Heat from a warm Arctic Ocean water layer, known as the Atlantic Water Layer, is vertically transported by double‐diffusive convection. This process frequently is evidenced by a staircase structure. We relate changes in staircase properties to both the background oceanographic setting as well as to an anomalously warm water pulse which entered the Arctic Ocean in the 1990s–2000s. We show that staircase properties are likely related to the propagation of warm water intrusions and subsequent dissipation of their property gradients. This work sheds light on what the western Arctic Ocean may look like under continued climate change. Key Points: Atlantic Water layer diffusive‐convective staircases in the Beaufort Gyre exhibit a west‐east gradient in layer thicknessLayer thicknesses are correlated with the stratification overlying, and intrusive features surrounding, the Atlantic Water coreThis layer thickness gradient may be due to lateral propagation of a warm Atlantic water pulse that entered the central Arctic in the 2000s [ABSTRACT FROM AUTHOR]