The Equatorial Undercurrent and the Oxygen Minimum Zone in the Pacific
The Equatorial Undercurrent and the Oxygen Minimum Zone in the Pacific
复制标题
DOI：
10.1029/2019gl082692
复制
发表时间：
2019-06-28
影响因子：
5.2
通讯作者：
Dunne, John P.
中科院分区：
文献类型：
--
作者：
Busecke, Julius J. M.;Resplandy, Laure;Dunne, John P.
变暖驱动的赤道太平洋最低含氧区（OMZ）的扩张将使含氧量极低的水域更接近海洋表面，并可能影响全球碳/养分循环和当地生态系统。然而，全球粗地球系统模型（ESM）显示出不同的趋势，很难限制上层 OMZ 的未来变化。使用具有高分辨率海洋（1/10 度）的 ESM，我们表明赤道潜流 (EUC) 动力学的真实表示对于表示上部 OMZ 结构及其时间变化至关重要。我们证明，较粗略的 ESM 通常会歪曲 EUC，导致 OMZ 不切实际的“倾斜”（例如，向东变浅），并对 EUC 变化过度敏感，压倒扩散和生物学等其他重要过程。这一缺点损害了再现 OMZ 变化的能力，并可以解释 ESM 预测中的不同趋势。 简单语言摘要 我们预计，随着气候变暖，海洋低氧区域将会扩大。这种扩张将使低氧水域更接近太平洋海洋表面，并影响全球碳吸收和海洋动物之间的相互作用。我们表明，常用的低分辨率气候模型歪曲了主要洋流之一——赤道潜流的特征，并对低氧水域的深度产生了影响。使用更高分辨率的气候模型，我们完善了赤道暗流和赤道太平洋低氧区域的表示。我们假设低分辨率模型的缺点会损害我们再现低氧区域及其对气候变化的响应的能力。
Warming-driven expansion of the oxygen minimum zone (OMZ) in the equatorial Pacific would bring very low oxygen waters closer to the ocean surface and possibly impact global carbon/nutrient cycles and local ecosystems. Global coarse Earth System Models (ESMs) show, however, disparate trends that poorly constrain these future changes in the upper OMZ. Using an ESM with a high-resolution ocean (1/10 degrees), we show that a realistic representation of the Equatorial Undercurrent (EUC) dynamics is crucial to represent the upper OMZ structure and its temporal variability. We demonstrate that coarser ESMs commonly misrepresent the EUC, leading to an unrealistic "tilt" of the OMZ (e.g., shallowing toward the east) and an exaggerated sensitivity to EUC changes overwhelming other important processes like diffusion and biology. This shortcoming compromises the ability to reproduce the OMZ variability and could explain the disparate trends in ESMs projections.Plain Language Summary We expect an expansion of the ocean low-oxygen areas as the climate warms. This expansion would bring low-oxygen waters closer to the ocean surface in the Pacific Ocean and affect the global uptake of carbon and interactions between marine animals. We show that commonly used low-resolution climate models misrepresent characteristics of one of the major ocean currents-the Equatorial Undercurrent-with implications for the depth of the low-oxygen waters. Using a higher-resolution climate model we refine the representation of the Equatorial Undercurrent and the low-oxygen areas in the equatorial Pacific. We postulate that shortcomings of low-resolution models compromise our ability to reproduce areas of low oxygen and their response to climate change.