Multidecadal trends of oxygen and their controlling factors in the western North Pacific
Multidecadal trends of oxygen and their controlling factors in the western North Pacific
复制标题
DOI：
10.1002/2014gb005065
复制
发表时间：
2015-07
影响因子：
5.2
通讯作者：
D. Sasano;Yusuke Takatani;N. Kosugi;Toshiya Nakano;T. Midorikawa;M. Ishii
中科院分区：
文献类型：
--
作者：
D. Sasano;Yusuke Takatani;N. Kosugi;Toshiya Nakano;T. Midorikawa;M. Ishii
分析了1987-2011年西北太平洋165°E高频重复剖面的溶解氧(O2)浓度变化率。在北部副热带到副热带-亚北极过渡地带，在广泛的等温地平线范围内，观测到了氧气显著减少的趋势。在25°N~30°N的北太平洋副热带模式水中，25°N~30°N的25.3σθ上，O2的下降速率达到−0.45±0.16µmolkg−1yr−1。这主要归因于等水层加深和海洋变暖引起的氧溶解度的降低。在北太平洋中水，O2下降的速度加快(−为0.44±0.14µmolkg−1yr−1，σθ为26.8mmolkg)，并与源水表观氧利用的净增加有关。在32.5°N~35°N之间的亚热带最低氧层，27.3σθ上O2的下降速率显著(−0.22±0.05µmolkg−1yr−1)。这可能是由于低氧水向西输送的增加所致。这些控制沿165°E区段O2变化的不同驱动因素与沿137°E区段的作用相同(前面分析过)，也解释了这些区段之间O2下降速率的差异。此外，在5°N和10°N之间的26.8MOL附近，两个断面都有显著的O2升高趋势(165°E断面+0.36±0.04µσθkg−1yr−1)。这些结果表明，气候变暖和环流变化正在导致西北太平洋大片海域溶解O2的数十年变化。
The rate of change of dissolved oxygen (O2) concentrations was analyzed over 1987–2011 for the high‐frequency repeat section along 165°E in the western North Pacific. Significant trends toward decreasing O2 were detected in the northern subtropical to subtropical‐subarctic transition zones over a broad range of isopycnal horizons. On 25.3σθ between 25°N and 30°N in North Pacific Subtropical Mode Water, the rate of O2 decrease reached −0.45 ± 0.16 µmol kg−1 yr−1. It is largely attributed to a deepening of isopycnal horizons and to a reduction in oxygen solubility associated with ocean warming. In North Pacific Intermediate Water, the rate of O2 decrease was elevated (−0.44 ± 0.14 µmol kg−1 yr−1 on 26.8σθ) and was associated with net increases in apparent oxygen utilization in the source waters. On 27.3σθ in the subtropical Oxygen Minimum Layer (OML) between 32.5°N and 35°N, the rate of O2 decrease was significant (−0.22 ± 0.05 µmol kg−1 yr−1). It was likely due to the increases in westward transport of low‐oxygen water. These various drivers controlling changes in O2 along the 165°E section are the same as those acting along 137°E (analyzed previously) and also account for the differences in the rate of O2 decrease between these sections. Additionally, in the tropical OML near 26.8σθ between 5°N and 10°N, significant trends toward increasing O2 were detected in both sections (+0.36 ± 0.04 µmol kg−1 yr−1 in the 165°E section). These results demonstrate that warming and circulation changes are causing multidecadal changes in dissolved O2 over wide expanses of the western North Pacific.