ABSTRACT

A recent analysis of observed oxygen changes shows a 2% decline in marine oxygen during the 50 years since 1960. However, these oxygen changes vary on time scales related to climate modes and by regions, including areas of increasing oxygen. Hence, any local oxygen change is related to various subsets of these drivers for the different regions and time scales. Here we provide an overview of drivers presently known for the different regions in the upper and deep ocean and the regional influence of climate modes, focussing on decadal and longer time scales for open ocean regions. We identify and compile regions where changes in solubility, stratification, decadal to multidecadal variability, source waters (either increases or decreases), overturning circulation or circulation-driven changes, and biological or nutrient stimulation have been shown to play a role in oxygen changes. The superposition and interaction of drivers and processes makes the decomposition of the impact on oxygen distribution difficult. Nevertheless, the description of the different drivers identified will help in better understanding the oxygen changes observed and lead to better verification of numerical models of future ocean oxygen levels.

摘要

最近对观测到的氧气变化的分析表明，自1960年以来的50年中，海洋氧气下降了2％。但是，这些氧气变化随与气候模式有关的时间尺度以及各地区（包括氧气增加的区域）而变化。因此，对于不同的区域和时间范围，任何局部的氧气变化都与这些驱动因素的各个子集有关。在这里，我们概述了目前已知的上层和深层海洋不同区域的驱动因素以及气候模式的区域影响，重点是开放海洋区域的年代际和较长时间尺度。我们确定并编辑溶解度，分层，年代际到十年际变化，源水（增加或减少），翻转环流或由环流驱动的变化的区域，以及生物或营养刺激已显示出对氧气变化的作用。驱动器和过程的叠加和相互作用使得对氧气分布的影响难以分解。然而，对确定的不同驱动因素的描述将有助于更好地了解观察到的氧气变化，并有助于更好地验证未来海洋氧气水平的数值模型。