Low ocean-floor rises regulate subpolar sea surface temperature by forming baroclinic jets

• Published in: Nature Communications
• Main Authors: Mitsudera, H., Miyama, T., Nishigaki, H., Nakanowatari, T., Nishikawa, H., Nakamura, T., Wagawa, T., Furue, R., Fujii, Y., Ito, S.
• Format: Text
• Language: English
• Published: Nature Publishing Group UK 2018
• Subjects: Article; Pacific; Subarctic
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5864925/; http://www.ncbi.nlm.nih.gov/pubmed/29568009; https://doi.org/10.1038/s41467-018-03526-z

Sea surface temperature (SST) fronts in mid- to high-latitude oceans have significant impacts on extratropical atmospheric circulations and climate. In the western subarctic Pacific, sharp SST fronts form between the cold subarctic water and the recently found quasi-stationary jets that advect warm waters originating in the Kuroshio northeastward. Here we present a new mechanism of the jet formation paying attention to the propagation of baroclinic Rossby waves that is deflected by eddy-driven barotropic flows over bottom rises, although their height is low (~500 m) compared with the depth of the North Pacific Ocean (~6000 m). Steered by the barotropic flows, Rossby waves bring a thicker upper layer from the subtropical gyre and a thinner upper layer from the subarctic gyre, thereby creating a thickness jump, hence a surface jet, where they converge. This study reveals an overlooked role of low-rise bottom topography in regulating SST anomalies in subpolar oceans.