A link between U.S. East Coast sea level rise and offshore ocean heat uptake

In this work I will present results that establish a link between subtropical North Atlantic heat content and coastal sea level south of Cape Hatteras. Co-variability in these fields, diagnosed using a newly developed high resolution (1/12 degree) regional ocean model (NWA12), appears across seasonal to inter-annual timescales. This link is realized as the result of a shore-ward mass redistribution driven by offshore warming at depths below the continental shelf break. As recent studies have identified mode and intermediate waters as a dominant reservoir of ocean heat taken up from the atmosphere (Li et al. 2023), this mechanistic link establishes a connection between the changing nature of ocean circulation / heat content and coastal sea level. Results reveal that a significant fraction (>0.5) of coastal sea level variance at seasonal to inter-annual timescales can be explained considering only offshore density change and ocean hypsometry (the distribution of ocean area with depth). With a combination of observing systems (e.g. Argo, GRACE, satellite altimetry, and tide gauge networks), the relationship identified here can next be leveraged to monitor and explain coastal sea level change across a diverse set of regions experiencing varied rates of sea level rise.