Atmosphere and Ocean Research Institute, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8568, Japan.
Nat Commun. 2013;4:2419. doi: 10.1038/ncomms3419.
Vertical mixing in the ocean is a key driver of the global ocean thermohaline circulation, one of the most important factors controlling past and future climate change. Prior observational and theoretical studies have focused on intense tidal mixing near the sea bottom (near-field mixing). However, ocean general circulation models that employ a parameterization of near-field mixing significantly underestimate the strength of the Pacific thermohaline circulation. Here we demonstrate that tidally induced mixing away from the sea bottom (far-field mixing) is essential in controlling the Pacific thermohaline circulation. Via the addition of far-field mixing to a widely used tidal parameterization, we successfully simulate the Pacific thermohaline circulation. We also propose that far-field mixing is indispensable for explaining the presence of the world ocean's oldest water in the eastern North Pacific Ocean. Our findings suggest that far-field mixing controls ventilation of the deep Pacific Ocean, a process important for ocean carbon and biogeochemical cycles.
海洋中的垂直混合是全球海洋热盐环流的关键驱动力，是控制过去和未来气候变化的最重要因素之一。先前的观测和理论研究集中在海底部附近的强烈潮汐混合（近场混合）上。然而，采用近场混合参数化的海洋环流模型大大低估了太平洋热盐环流的强度。在这里，我们证明了远离海底的潮汐混合（远场混合）对于控制太平洋热盐环流至关重要。通过在广泛使用的潮汐参数化中添加远场混合，我们成功地模拟了太平洋热盐环流。我们还提出，远场混合对于解释东太平洋存在世界海洋最古老的水是必不可少的。我们的研究结果表明，远场混合控制着太平洋深部的通风，这一过程对于海洋碳和生物地球化学循环非常重要。
