The Florida Current (FC) refers to the Gulf Stream across the Florida Straits between Florida and the Bahamas. Its volume transport has been measured continuously since 1982 using submarine cables across the Florida Straits at 27°N by NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML). A previous study (Piecuch and Beal, 2023) reported that the FC volume transport declined significantly by -1.2 ± 1.0 Sv in the past 40 years (since 1982). This statistically significant trend derived from the cable data and other in situ and altimetry data was presented as “the first unequivocal evidence for a recent multidecadal decline in this climate-relevant component of ocean circulation”. In a new study published in Nature Communications, a team of scientists led by sea-going oceanographers at the University of Miami and NOAA’s AOML found that the submarine cable measurement record requires a correction for the secular change in the Earth’s magnetic field. The geomagnetic correction removed a spurious trend, updating the FC transport trend estimate to −0.1 ± 0.2 Sv per decade (during 1982 – 2023), which is statistically insignificant. This study further reevaluated the Atlantic Meridional Overturning Circulation (AMOC) transport across the RAPID AMOC observing array at ~26.5°N given that the FC is a key component of the AMOC. The new estimate reduced the AMOC trend during 2004 – 22 from −1.3 ± 0.7 Sv per decade to −0.8 ± 0.7 Sv per decade, a 40% reduction.
Figure 6a from Volkov et al. (2024). The time series of the daily FC volume transport: (blue) not corrected for the secular change in the Earth’s Magnetic Field (EMF), (red) corrected for the secular change in the EMF. The linear trends of the FC transport not corrected and corrected for the EMF are shown by the blue and red lines, respectively.
Volkov, D.L., Smith, R.H., Garcia, R.F. Smeed, D.A., Moat, B.I, Johns, W.E. & Baringer, M.O. (2024). Florida Current transport observations reveal four decades of steady state. Nature Communications 15, 7780. https://doi.org/10.1038/s41467-024-51879-5
Piecuch, C. G., & Beal, L. M. (2023). Robust weakening of the Gulf Stream during the past four decades observed in the Florida Straits. Geophysical Research Letters, 50, e2023GL105170. https://doi.org/10.1029/2023GL105170
NOAA AOML Western Boundary Time Series (WBTS) project
NOAA AOML Daily Mean Transport Estimates From the Submarine Cable Voltage
Reassessing the stability of the Florida Current: New insights from 40 years of observations
Ocean to Climate 