GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
NOAA/AOML, Miami, FL, USA.
Nat Commun. 2020 Jul 31;11(1):3829. doi: 10.1038/s41467-020-17601-x.
The direct response of the tropical mixed layer to near-inertial waves (NIWs) has only rarely been observed. Here, we present upper-ocean turbulence data that provide evidence for a strongly elevated vertical diffusive heat flux across the base of the mixed layer in the presence of a NIW, thereby cooling the mixed layer at a rate of 244 W m over the 20 h of continuous measurements. We investigate the seasonal cycle of strong NIW events and find that despite their local intermittent nature, they occur preferentially during boreal summer, presumably associated with the passage of atmospheric African Easterly Waves. We illustrate the impact of these rare but intense NIW induced mixing events on the mixed layer heat balance, highlight their contribution to the seasonal evolution of sea surface temperature, and discuss their potential impact on biological productivity in the tropical North Atlantic.
热带混合层对近惯性波（NIWs）的直接响应很少被观测到。在这里，我们呈现了上层海洋湍流数据，这些数据为在存在 NIW 的情况下混合层底部垂直扩散热通量显著增加提供了证据，从而以 244 W m 的速率冷却混合层，在连续测量的 20 小时内。我们研究了强 NIW 事件的季节性周期，发现尽管它们具有局部间歇性，但它们主要发生在北大西洋夏季，可能与大气非洲东风波的传播有关。我们说明了这些罕见但强烈的由 NIW 引起的混合事件对混合层热量平衡的影响，强调了它们对海表温度季节性演变的贡献，并讨论了它们对热带北大西洋生物生产力的潜在影响。
