Abstract. Recent estimates of the global inventory of dissolved oxygen (DO) have suggested a decrease of 2 % since the 1960s. However, due to the sparse historical oxygen data coverage, the DO inventory exhibits large regional uncertainties at interannual timescale. Using ISASO2, a new DO Argo-based optimally interpolated climatology https://doi.org/10.17882/52367 (Kolodziejczyk et al.,2021), we have estimated an updated regional oxygen inventory. Over the long term (~1980–2013), comparing the ISASO2 Argo fields with the first guess WOA18 built from the DO bottle samples fields extracted from WOD18, the broad tendency to global ocean deoxygenation remains robust in the upper 2000 m with -451±243 Tmol per decade. The oxygen decline is more pronounced in the key ventilation areas of the Southern Ocean and North Atlantic, except in the Nordic Seas, where oxygen has increased. Over the shorter timescale of the Argo period (2005–2019), the deoxygenation tendency seems globally amplified (-1211±218 Tmol per decade). However, DO changes exhibit stronger amplitude and contrasted regional patterns, likely driven by interannual modes of variability in regions as, for instance, the North Atlantic Subpolar-gyre. The recent changes in Apparent Oxygen Utilization mainly explain the interannual variability in the ventilation regions. However, Argo DO coverage is still incomplete at the global and calibration method development are still in progress. Continuing the monitoring of the seasonal to interannual and regional to global DO variability from ISASO2 will improve our ability to reduce uncertainties on global and regional DO inventory.

中文翻译：

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ISASO2：海洋溶解氧变化的最新趋势和区域模式

摘要。最近对全球溶解氧 (DO) 存量的估计显示，自 20 世纪 60 年代以来，溶解氧 (DO) 总量减少了 2%。然而，由于历史氧数据覆盖范围稀疏，溶解氧库存在年际时间尺度上表现出较大的区域不确定性。使用 ISASO2（一种新的基于 DO Argo 的最佳插值气候学https://doi.org/10.17882/52367（Kolodziejczyk等人，2021 年）），我们估算了更新的区域氧气库存。从长远来看（~1980-2013），将 ISASO2 Argo 场与根据 WOD18 提取的 DO 瓶样本场建立的第一个猜测 WOA18 进行比较，全球海洋脱氧的广泛趋势在 2000 米上部仍然强劲，-451±每十年 243 Tmol。在南大洋和北大西洋的关键通风区域，氧气下降更为明显，但北欧海域的氧气有所增加。在Argo时期较短的时间尺度（2005-2019）中，脱氧趋势似乎在全球范围内放大（每十年-1211±218 Tmol）。然而，溶解氧变化表现出更强的幅度和对比鲜明的区域模式，这可能是由北大西洋副极地环流等区域的年际变化模式驱动的。最近表观耗氧量的变化主要解释了通风区域的年际变化。然而，Argo DO在全球的覆盖范围仍然不完整，校准方法的开发仍在进行中。继续监测 ISASO2 的季节到年际以及区域到全球溶解氧变化将提高我们减少全球和区域溶解氧库存不确定性的能力。