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

Area of Science:

• Oceanography
• Atmospheric Science
• Climate Science

Background:

• Sea surface temperature (SST) fronts significantly impact extratropical atmospheric circulation and climate.
• Sharp SST fronts are observed in the western subarctic Pacific, separating cold subarctic water from warm, Kuroshio-originating jets.

Purpose of the Study:

• To present a novel mechanism for the formation of quasi-stationary jets in the western subarctic Pacific.
• To elucidate the role of ocean bottom topography in regulating SST anomalies in subpolar regions.

Main Methods:

• Investigated the propagation of baroclinic Rossby waves.
• Analyzed the influence of eddy-driven barotropic flows over low-rise bottom topography.
• Examined the interaction between Rossby waves and topographical steering.

Main Results:

• Barotropic flows over low-rise topography (around 500m) deflect Rossby waves.
• Deflected Rossby waves induce thickness variations in ocean layers, with thicker layers from subtropical gyre and thinner from subarctic gyre.
• Convergence of these varying layer thicknesses creates a surface jet, forming the SST front.

Conclusions:

• Low-rise ocean bottom topography plays a crucial, previously overlooked role in forming SST fronts.
• This mechanism highlights the interaction between topography, Rossby waves, and ocean circulation in shaping subpolar climate patterns.