Slow Down of the Gulf Stream during 1993\u20132016

Shenfu Dong,Gustavo J Goni,Molly O Baringer

doi:10.1038/s41598-019-42820-8

Abstract

The Gulf Stream, the main heat-carrier from low to high latitudes in the North Atlantic Ocean, influences the climate and weather in the northern hemisphere. In this study we determine and analyze the position, speed, and width of the Gulf Stream (GS) from 80°W–50°W using satellite altimeter sea surface height (SSH) measurements to examine the possible link between changes in the strength of the GS and coastal sea levels along the U.S. East Coast. During our 24-year study period (1993–2016), the GS experienced a southward shift east of 65°W after passing the New England Seamount chain. This southward shift was accompanied by a weakening of the GS, associated with an increase in SSH to the north of the GS. West of 70°W, however, we found no statistically significant trends in the GS properties, consistent with results based on in situ measurements. This lack of a trend to the west fails to support a direct link between a long-term slowdown of the GS west of 70°W and sea level rise acceleration along the U.S. East Coast, though a slowdown of the GS east of 65°W may contribute to sea level rise. It is also possible that heat carried to the region by the GS may be responsible for these observed sea level changes.

Highlights

The Gulf Stream (GS), the western boundary current in the North Atlantic, influences the weather and climate patterns of eastern North America and Western Europe through both hydrodynamic and thermodynamic processes[1,2,3]
We evaluated the methodology for determining GS properties from altimeter sea surface height (SSH) fields by interpolating the SSH-derived properties into in situ measurement time and location and comparing them with those from in situ measurements
As our analyses focused on changes in the GS on interannual to longer time scales, all current properties were smoothed by a Butterworth filter to remove signals with periods less than one year

Summary

Introduction

The Gulf Stream (GS), the western boundary current in the North Atlantic, influences the weather and climate patterns of eastern North America and Western Europe through both hydrodynamic and thermodynamic processes[1,2,3]. Using a sea surface height (SSH) gradient as an indication of GS strength, Ezer et al.[15] argued that weakening of the GS during 1993–2011, as observed by satellite altimetry in the region 75.5°W–70°W, corresponded to a reduced SSH difference across the GS This reduced SSH difference resulted in an increase in SSH to the north of the GS and a decrease in SSH to the south. Ezer[18] compared sea level difference between Atlantic City and Bermuda from tide gauges and altimeter with the total transport across the entire Oleander section, and found good agreement among different data This suggests that the discrepancies in GS strength from pervious studies[15,17] are likely due to different definitions and spatial variations. We discuss the potential link between the GS and sea level rise along the U.S East Coast

Methods

Results

Discussion

Conclusion