Ocean Circulation Near Cape Hatteras: Observations of Mean and Variability

Abstract

Introduction and BackgroundMany oceanographic processes occur in the vicinity of Cape Hatteras USA, and together contribute to the complex flow regime there. Cape Hatteras and its sub-surface offshore extension, Diamond Shoals, mark the separation of the continental shelf along the U.S east coast into two distinct regions: South Atlantic Bight (SAB) and Mid Atlantic Bight (MAB). Like the coastline, the shelfbreak (∼100-m isobath) changes its orientation from south to north, turning from about SW-NE to almost S-N at the "The Point," offshore of Cape Hatteras near 35.5°N (Figure 1a). The Point is where the Gulf Stream typically separates from the continental margin, and it is also usually the southernmost detachment location of the Shelfbreak Jet (Csanady & Hamilton, 1988;Gawarkiewicz et al., 2008). On the adjacent continental shelf, both the MAB and SAB shelf waters generally flow toward Cape Hatteras. To better understand the seawater exchange between the continental shelf and the adjacent open ocean in this region, an integrated observational and modeling program, Processes driving Exchange At Cape Hatteras

Observations of Shelf‐Ocean Exchange in the Northern South Atlantic Bight Driven by the Gulf Stream

“…Empirical orthogonal function analysis using records from the entire array is discussed in Han et al. (2022), and analysis of Gulf Stream variability based on the 5 CPIESs is presented in Andres (2021b). The emphasis here is on combining measurements from one of the ADCPs with measurements and derived quantities from a nearby CPIES to study shelf‐ocean exchange processes by leveraging these simultaneous measurements of the SAB outer shelf and upper slope.…”

“…The main PEACH in situ array (Seim et al, 2022) was deployed in April 2017 and was recovered 19 months later in November 2018. Empirical orthogonal function analysis using records from the entire array is discussed in Han et al (2022), and analysis of Gulf Stream variability based on the 5 CPIESs is presented in Andres (2021b). The showing the locations of P7 and A8 deployed for 19 months during Processes driving Exchange at Cape Hatteras (PEACH) and a schematic of the regional circulation.…”

“…Processed PEACH ADCP data are available at Haines et al. (2022b). The Florida Current data are made freely available on the Atlantic Oceanographic and Meteorological Laboratory web page (NOAA, AOML, 2023).…”

“…On the shelf onshore of the separating Gulf Stream, at the so‐called “Hatteras Front,” poleward‐flowing SAB shelf water masses (generally salty/warm) converge with cool/fresh equatorward‐flowing shelf water masses from the Middle Atlantic Bight (MAB), which stretches from Cape Hatteras to Cape Cod near 41.5°N, 70°W. The location of the Hatteras Front sweeps north and south past Cape Hatteras under wind forcing (Savidge & Austin, 2007) and due to Gulf Stream influence (Han et al., 2021, 2022; Savidge & Bane, 2001). The result of the convergent shelf flow is an overall net export into the open ocean.…”

“…Middle Atlantic Bight (MAB), which stretches from Cape Hatteras to Cape Cod near 41.5°N, 70°W. The location of the Hatteras Front sweeps north and south past Cape Hatteras under wind forcing (Savidge & Austin, 2007) and due to Gulf Stream influence (Han et al, 2021(Han et al, , 2022Savidge & Bane, 2001). The result of the convergent shelf flow is an overall net export into the open ocean.…”