Nonstationary Roles of Regional Forcings in Driving Low-Frequency Sea Level Variability Along the U.S. East Coast Since the 1950s

Abstract

The nonstationary roles of regional forcings from alongshore wind stress and sea level pressure (SLP) in driving low-frequency (interannual-to-decadal) sea level variability along the U.S. east coast for the 1959–2020 period are investigated. The role of regional forcings increases with time north of Cape Hatteras particularly during summer when their contributions to the variance of observed summertime coastal sea level anomalies increase by approximately 58%–87% from 1959–1989 to 1990–2020. The enhanced impact of regional forcings in recent decades results from an increase in the Inverted Barometer (IB) effect that act constructively with alongshore wind stress especially during summer, and to a lesser extent for the Gulf of Maine during fall. The summertime North Atlantic Oscillation (NAO) is largely responsible for the increased IB effect, owing to the stronger NAO-associated low SLP anomalies centered around the Mid-Atlantic Bight in recent decades compared to earlier decades.