Department of Marine Sciences, University of Georgia, Athens, GA, USA.
Sci Rep. 2018 Oct 30;8(1):16004. doi: 10.1038/s41598-018-34401-y.
The California Current System is characterized by summertime wind-driven upwelling, high biological productivity, and an intense equatorward upwelling jet. The upwelling jet is generally located close to shore to the north of Cape Blanco (43°N), but it separates from the coast at the cape during summer extending farther offshore downstream of the separation point. Jet separation results in a wider region influenced by cold, nutrient-rich upwelled waters, strongly affecting biological productivity, mesoscale activity, and air-sea interactions. Flow-topography interactions are thought to play a dominant role in jet separation. Here, we use a high-resolution ocean model to show that the wind stress curl is a dominant forcing controlling jet separation, and that separation can occur independently of flow-topography interactions. While jet separation occurs in simulations with realistic wind stress curl and modified topography with no submarine banks or capes, jet separation is substantially reduced when the wind stress curl is removed, even in the presence of realistic topography. This novel insight indicates that future changes in winds, as the predicted delay in the seasonal development of wind stress curl intensifications, may result in substantial changes in ocean circulation in the California Current System.
加利福尼亚海流系统的特点是夏季风驱动的上升流、高生物生产力和强烈的赤道上升流射流。上升流射流通常位于布兰科角（43°N）以北的近岸处，但在夏季，它会在该角处与海岸分离，并在分离点的下游更远的海域延伸。射流分离导致受寒冷、富营养上升水影响的区域更广，强烈影响生物生产力、中尺度活动和海气相互作用。人们认为流地形相互作用在射流分离中起着主导作用。在这里，我们使用高分辨率海洋模型表明，风应力旋度是控制射流分离的主要驱动力，并且分离可以独立于流地形相互作用发生。虽然在模拟中，当存在现实的地形时，即使没有海底银行或海角，真实风应力旋度和修改地形也会导致射流分离，但当风应力旋度被移除时，射流分离会大大减少。这一新颖的见解表明，未来风的变化，如预测的风应力旋度增强季节发展的延迟，可能导致加利福尼亚海流系统的海洋环流发生重大变化。
