A Link Between U.S. East Coast Sea Level and North Atlantic Subtropical
Ocean Heat Content
Abstract
Using a recently developed 1/12th degree regional ocean model, we
establish a link between U.S. East Coast sea level variability and
offshore upper-ocean heat content change. This link manifests as a
cross-shore mass redistribution driven by an offshore thermosteric sea
level response to subsurface warming or cooling. Approximately
50\% of simulated monthly to inter-annual coastal sea
level variance south of Cape Hatteras can be statistically accounted for
by this mechanism, realized as a function of regional ocean hypsometry,
gyre scale warming, and the depth-dependence of density change. This
response to offshore warming explains the non-stationarity of U.S. East
coast sea level covariance, specifically observed and modeled behavior
after $\sim$ 2010. Since approximately 2010, elevated
rates of sea level rise south of Cape Hatteras can be partly explained
as the result of shore-ward mass redistribution due to offshore
sub-surface warming within the North Atlantic subtropical gyre. These
results reveal a mechanism that connects local coastal sea level to a
broader region and identifies the influence of regional heat content
changes on coastal sea level. This analysis presents a framework for
identifying new regions that may be susceptible to enhanced sea level
rise due to ocean warming and helps bridge the gap between quantifying
large scale change and anticipating local coastal impacts like flooding
and storm surge.