Inferring Florida Current volume transport from satellite altimetry
Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)
Session: Science I: Climate data records for understanding the causes of global and regional sea level variability and change
Presentation type: Type Forum
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 value 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. Here, we explore 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 suitable 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 overall accuracy of the altimetry-derived transport is lower than that of the cable transport (2.1-2.3 Sv versus 1.5 Sv). We further 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.