Geophysical Institute, University of Bergen/Bjerknes Centre for Climate Research, Bergen, Norway.
NORCE Norwegian Research Centre/Bjerknes Centre for Climate Research, Bergen, Norway.
Nat Commun. 2023 Jun 20;14(1):3649. doi: 10.1038/s41467-023-38718-9.
Atlantic Niño is a major tropical interannual climate variability mode of the sea surface temperature (SST) that occurs during boreal summer and shares many similarities with the tropical Pacific El Niño. Although the tropical Atlantic is an important source of CO to the atmosphere, the impact of Atlantic Niño on the sea-air CO exchange is not well understood. Here we show that the Atlantic Niño enhances (weakens) CO outgassing in the central (western) tropical Atlantic. In the western basin, freshwater-induced changes in surface salinity, which considerably modulate the surface ocean CO partial pressure (pCO), are the primary driver for the observed CO flux variations. In contrast, pCO anomalies in the central basin are dominated by the SST-driven solubility change. This multi-variable mechanism for pCO anomaly differs remarkably from the Pacific where the response is predominantly controlled by upwelling-induced dissolved inorganic carbon anomalies. The contrasting behavior is characterized by the high CO buffering capacity in the Atlantic, where the subsurface water mass contains higher alkalinity than in the Pacific.
大西洋 Niño 是一种主要的热带年际气候变率模式，发生在北方夏季，与热带太平洋厄尔尼诺现象有许多相似之处。尽管热带大西洋是大气中 CO 的重要来源，但大西洋 Niño 对海气 CO 交换的影响还不太清楚。在这里，我们表明大西洋 Niño 增强（减弱）了中（西）热带大西洋的 CO 排放。在西部海域，由淡水引起的表面盐度变化极大地调节了表层海洋 CO 分压（pCO），是观测到的 CO 通量变化的主要驱动因素。相比之下，中部海域的 pCO 异常主要由 SST 驱动的溶解度变化控制。这种多变量的 pCO 异常机制与太平洋明显不同，太平洋的响应主要受上升流引起的溶解无机碳异常控制。这种对比行为的特征是大西洋具有较高的 CO 缓冲能力，其中次表层水体的碱度高于太平洋。
