Abstract
The nearly four-decades-long quasi-continuous daily measurements of the
Florida Current (FC) volume transport at 27ºN represents the longest
climate record of a boundary current in existence. Given the extremely
high utility of this submarine cable-collected time series for
monitoring the Atlantic meridional overturning circulation, as well as
for improving understanding and prediction of the regional weather,
climate phenomena, coastal sea-level, and ecosystem dynamics, efforts
are underway to establish a suitable backup observing system in case the
cable becomes inoperable in the future. This study explores the utility
of along-track satellite altimetry measurements since 1993 as a
potential cable backup by establishing the relationship between the
cross-stream sea surface height gradients and the FC volume transport
derived from cable measurements and ship sections. We find that despite
the lower temporal resolution, satellite altimetry can indeed serve as a
decent but limited backup observing system. The FC transport inferred
from satellite altimetry captures about 60% of the variability observed
in the concurrent cable estimates, and the estimated error bars for the
altimetry-derived transport are larger than those of the cable transport
(2.1 Sv versus 1.5 Sv). We nevertheless demonstrate that satellite
altimetry reproduces the seasonal, intra-seasonal, and inter-annual
variability of the FC transport fairly well, as well as large transport
anomalies during extreme weather events, such as tropical storms and
hurricanes. The altimetry-derived transport can be provided in near-real
time and serve the need to fill in data gaps in the cable record and
assess its quality over time.