德国亥姆霍兹海洋研究中心Brandt Peter团队最近的研究揭示，赤道大西洋的季节性生产力由独特的风驱动过程形成。相关论文于2025年1月6日发表在《自然—地球科学》杂志上。
据悉，东赤道大西洋拥有一个多产的依赖于硝酸盐的向上供应的海洋生态系统，而硝酸盐是该地区主要的限制性营养物质。地表叶绿素水平的升高表明，年生产力峰值出现在北半球的夏季，大致与东风增强的时间一致。为了提高赤道大西洋的生产力，富含硝酸盐的水会上升到赤道暗流上方的湍流层。
研究人员对两次跨大西洋赤道调查的数据，以及赤道系泊的延长时间序列进行分析，以探究三个独立的风驱动过程是如何塑造赤道大西洋生产力的季节性的：(1)硝酸盐化浅滩对增强的东风的响应；(2)赤道暗流核心深度由最大东向速度所定义，受海盆尺度赤道驻波的年振荡控制；(3)赤道暗流核上方剪切带的混合强度受局地和瞬时风的控制。
研究结果强调，这三种机制的相互作用塑造了赤道大西洋营养供应和生产力的独特季节性循环，受赤道暗流影响，4月的生产力最低，因浅层硝酸盐加上增强的混合，7月份的生产力最高。
附：英文原文
Title: Seasonal productivity of the equatorial Atlantic shaped by distinct wind-driven processes
Author: Brandt, Peter, Krner, Mareike, Moum, James N., Roch, Marisa, Subramaniam, Ajit, Czeschel, Rena, Krahmann, Gerd, Dengler, Marcus, Kiko, Rainer
Issue&Volume: 2025-01-06
Abstract: The eastern equatorial Atlantic hosts a productive marine ecosystem that depends on upward supply of nitrate, the primary limiting nutrient in this region. The annual productivity peak, indicated by elevated surface chlorophyll levels, occurs in the Northern Hemisphere summer, roughly coinciding with strengthened easterly winds. For enhanced productivity in the equatorial Atlantic, nitrate-rich water must rise into the turbulent layer above the Equatorial Undercurrent. Using data from two trans-Atlantic equatorial surveys, along with extended time series from equatorial moorings, we demonstrate how three independent wind-driven processes shape the seasonality of equatorial Atlantic productivity: (1) the nitracline shoals in response to intensifying easterly winds; (2) the depth of the Equatorial Undercurrent core, defined by maximum eastward velocity, is controlled by an annual oscillation of basin-scale standing equatorial waves; and (3) mixing intensity in the shear zone above the Equatorial Undercurrent core is governed by local and instantaneous winds. The interplay of these three mechanisms shapes a unique seasonal cycle of nutrient supply and productivity in the equatorial Atlantic, with a productivity minimum in April due to a shallow Equatorial Undercurrent and a productivity maximum in July resulting from a shallow nitracline coupled with enhanced mixing.
DOI: 10.1038/s41561-024-01609-9
Source: https://www.nature.com/articles/s41561-024-01609-9