Pan Okhotsk Research Center, Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan.
Application Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokohama, 236-0001, Japan.
Nat Commun. 2018 Mar 22;9(1):1190. doi: 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.
中高纬度海洋的海面温度（SST）锋面对温带大气环流和气候有重大影响。在西副极太平洋，冷水的寒冷亚极地水和最近发现的准定常喷流之间形成了急剧的 SST 锋面，这些喷流将源自黑潮的温暖水向东东北方向输送。在这里，我们提出了一种新的喷流形成机制，该机制关注的是斜压罗斯贝波的传播，这些波被底升上的涡旋驱动的正压流所偏转，尽管它们的高度（约 500 米）与北太平洋的深度（约 6000 米）相比很低。在正压流的引导下，罗斯贝波从副热带环流带来较厚的上层，从亚极地环流带来较薄的上层，从而形成一个厚度跳跃，因此在它们汇聚的地方形成了一个表面喷流。这项研究揭示了在调节亚极地海洋的 SST 异常方面，低海拔海底地形的一个被忽视的作用。
