The ocean absorbs anthropogenic carbon, slowing atmospheric CO₂ increase but driving ocean acidification. Long-term changes in the carbon system are typically assessed from single-point time series or from hydrographic sections spaced by decades. Using higher resolution observations (1–3 year⁻¹) from the Line P time series, we investigate processes modulating trends in the carbon system of the northeast subarctic Pacific. Dissolved inorganic carbon (DIC) and apparent oxygen utilization (AOU) from 1990 to 2019 reveal substantial trends over most of the upper water column along the 1,500 km coastal to open ocean transect. At the surface, an increasing trend in salinity-normalized DIC (sDIC₃₃) (+0.5 ± 0.4 μmol kg⁻¹ yr⁻¹) is associated with a decrease in pH (0.01–0.02 decade⁻¹) and a decrease in aragonite saturation state (0.04–0.08 decade⁻¹). These observed trends are driven by anthropogenic CO₂ uptake, partially offset by trends in surface salinity or temperature. Stratification associated with recent marine heat waves appears to have caused anomalously low surface pCO₂. sDIC₃₃ trends of similar magnitude were found below the seasonal thermocline on the 26.7–26.8 isopycnals (150–300 m), which are ventilated in the western Pacific. Roughly, a third (20%–50%) of the subsurface sDIC₃₃ trend is driven by increased remineralization, likely caused by long-term decreases in ventilation in the western Pacific. Bidecadal oscillations in the ventilation of the 26.7–26.8 isopycnals arising from the Lunar Nodal Cycle cause oscillations in sDIC₃₃ and AOU at the offshore end of our transect. We trace the oscillations to alternating periods of higher anthropogenic carbon uptake or higher carbon remineralization.

中文翻译：

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人为和气候对观测到的东北太平洋碳系统趋势的贡献

海洋吸收人为碳，减缓大气中 CO _{2 的}增加，但会导致海洋酸化。碳系统的长期变化通常是根据单点时间序列或间隔几十年的水文剖面来评估的。使用来自 P 线时间序列的更高分辨率观测（1-3 年^-1），我们研究了东北亚北极太平洋碳系统中调节趋势的过程。从 1990 年到 2019 年，溶解无机碳 (DIC) 和表观氧利用 (AOU) 揭示了沿 1,500 公里沿海至开阔洋横断面大部分上部水体的实质性趋势。在表面，盐度归一化 DIC (sDIC ₃₃ ) (+0.5 ± 0.4 μmol kg ^-1  yr ^-1) 与 pH 值的降低 (0.01–0.02 十进制^-1 ) 和文石饱和状态的降低 (0.04–0.08 十进制^-1 ) 相关。这些观察到的趋势是由人为 CO ₂吸收驱动的，部分被地表盐度或温度趋势所抵消。与最近的海洋热浪相关的分层似乎导致了异常低的地表 pCO ₂。在西太平洋通风的 26.7-26.8 等密度线 (150-300 m) 的季节性温跃层下方发现了类似量级的sDIC ₃₃趋势。粗略地说，地下 sDIC ₃₃的三分之一 (20%–50%)趋势是由再矿化增加推动的，这可能是由于西太平洋通风的长期减少所致。由月球节点周期引起的 26.7-26.8 等密度线的通风中的双十年振荡导致我们样带离岸端的sDIC ₃₃和 AOU 的振荡。我们将振荡追溯到更高的人为碳吸收或更高的碳再矿化的交替时期。