What Caused the Accelerated Sea Level Changes Along the U.S. East Coast During 2010–2015?

Abstract

Accelerated sea level rise was observed along the U.S. eastern seaboard south of Cape Hatteras during 2010–2015 with rates 5 times larger than the global average for the same time period. Simultaneously, sea levels decreased rapidly north of Cape Hatteras. In this study, we show that accelerated sea level rise recorded between Key West and Cape Hatteras was predominantly caused by a ~1 °C (0.2 °C/year) warming of the Florida Current during 2010–2015 that was linked to large‐scale changes in the Atlantic Warm Pool. We also show that sea level decline north of Cape Hatteras was caused by an increase in atmospheric pressure combined with shifting wind patterns, with a small contribution from cooling of the water column over the continental shelf. Results presented here emphasize that planning and adaptation efforts may benefit from a more thorough assessment of sea level changes induced by regional processes.

Regional Differences in Sea Level Rise Between the Mid‐Atlantic Bight and the South Atlantic Bight: Is the Gulf Stream to Blame?

“…During those 25 years, warming of the ocean can be seen especially in recent years as steric SSH rises. These results are consistent with the findings of Domingues et al (2018) who showed that between 2015 to 2017 temperature in the Florida Strait shifted from about −1°C cold anomaly to about +1°C warm anomaly. The difference in SSH (Figure 3c) shows the recent shift from a period of (relatively) higher SSH in the north (2009)(2010)(2011)(2012)(2013) to a period of (relatively) higher SSH in the south (2014-2017).…”

“…These results are consistent with the findings of Domingues et al (2018) who showed that between 2015 to 2017 temperature in the Florida Strait shifted from about −1°C cold anomaly to about +1°C warm anomaly. These oscillations are different in phase and amplitude for the northern and southern regions, thus pointing to different dynamic regional forcing as suggested before (Domingues et al, 2018;Valle-Levinson et al, 2017;Woodworth et al, 2016). Oscillations with periods of 2-5 years clearly impact the trends as seen from the low-pass filtered records (heavy black lines in Figure 3; these lines were obtained from the low-frequency EMD modes, as discussed later).…”

“…The focus here is on low-frequency modes that show clear oscillations, since these modes can create temporal changes in trends (e.g., Figure 5). Therefore, when the GS moves farther north, the GS velocity in the MAB is generally stronger, but the GS in the SAB is weaker-this could result in coastal sea level increase in the south and decrease in the north, as recently reported (Domingues et al, 2018). Therefore, when the GS moves farther north, the GS velocity in the MAB is generally stronger, but the GS in the SAB is weaker-this could result in coastal sea level increase in the south and decrease in the north, as recently reported (Domingues et al, 2018).…”

“…The study was motivated by recent observations (Domingues et al, 2018;Valle-Levinson et al, 2017;Wdowinski et al, 2016) that challenged previous perceptions of a "hot spot" of accelerated coastal sea (Boon, 2012;Ezer, 2013;Ezer et al, 2013;Ezer & Corlett, 2012;Goddard et al, 2015;Sallenger et al, 2012;Yin & Goddard, 2013). The earlier studies suggested that the regional SLR acceleration is related to potential slowdown of the GS flow and AMOC.…”

“…First, Wdowinski et al (2016) Domingues et al (2018) found that during 2010-2015 SLR rates in the SAB, south of Cape Hatteras, increased to~25 mm/year, some 5 times the global rates for this period, while SLR rates recently decreased north of Cape Hatteras. First, Wdowinski et al (2016) Domingues et al (2018) found that during 2010-2015 SLR rates in the SAB, south of Cape Hatteras, increased to~25 mm/year, some 5 times the global rates for this period, while SLR rates recently decreased north of Cape Hatteras.…”