Can seafloor voltage cables be used to study large-scale circulation? An investigation in the Pacific Ocean
Marine electromagnetic (EM) signals largely depend on three factors: oceanic transport (i.e., depth-integrated flow), Earth’s main magnetic field, and seawater’s electrical conductivity (which depends on the local temperature and salinity). Because of this, there has been recent interest in using marine EM signals to monitor and study ocean circulation. Our study utilizes voltage data from retired seafloor telecommunication cables in the Pacific Ocean to examine whether such cables could be used to monitor transport on large-oceanic scales. We process the cable data to isolate the seasonal and monthly variations, and evaluate the correlation between the processed data and numerical predictions of the electric field induced by ocean circulation. We find that the correlation between cable voltage data and numerical predictions strongly depends
on both the strength and coherence of the transport flowing across the cable, as well as the length of the cable. The cable within the Kuroshio Current had the highest correlation between data and predictions, whereas two of the cables in the Eastern Pacific gyre– a region with both low transport values and interfering transport signals across the cable– did not have any
clear correlation between data and predictions. Meanwhile, a third cable also located in the Eastern Pacific gyre had modest correlation between data and predictions– although the cable is very long and the transport values were low, it was located in a region of coherent transport flow across the cable. While much improvement is needed before utilizing seafloor voltage cables to study and monitor oceanic transport across wide oceanic areas, we believe that with additional work, the answer to our title’s question may eventually be yes.
Methodology and discussion of results in:
Velímský, J., Schnepf, N. R., Nair, M. C., and Thomas, N. P.: Can seafloor voltage cables be used to study large-scale circulation? An investigation in the Pacific Ocean, Ocean Sci. Discuss., https://doi.org/10.5194/os-2019-129, in press, 2021.
|Download Ocean Circulation Electromagnetism (OCEM) Data
|Data||.txt||9.95||Hourly data for the seafloor voltage cables HAW1NS.|
|Data||.txt||1.36||Hourly data for the seafloor voltage cable HAW3.|
|Data||.txt||16.40||Minutely data for the seafloor voltage cable OKI (1999-2001).|