Abstract. Subduction associated with mesoscale eddies is an important but difficult to observe process that can efficiently export carbon and oxygen to the mesopelagic zone (100–1000 db). Using a novel BGC-Argo dataset covering the western North Pacific (20–50° N, 120–180° E), we identified imprints of episodic subduction using anomalies in dissolved oxygen and spicity, a water mass marker. These subduction patches were present in 4.0 % (288) of the total profiles (7,120) between 2008 and 2019, situated mainly in the Kuroshio Extension region between March and August (70.6 %). Unlike eddy subduction processes observed at higher latitudes, roughly half (52 %) of these episodic events injected carbon- and oxygen-enriched waters below the annual permanent thermocline depth (450 db), with > 20 % occurring deeper than 600 db. Export rates within these subductions are estimated to be on the order of 85–159 mg C m⁻² day⁻¹ and 175 to 417 mg O₂ m⁻² day⁻¹. These mesoscale events would markedly increase carbon removal above that due to biological gravitational settling as well as oxygen ventilation in the region, both helping to support the nutritional and metabolic demands of mesopelagic organisms. Climate-driven patterns of increasing eddy kinetic energies in this region imply that the magnitude of these processes will grow in the future, meaning that these unexpectedly effective small-scale subduction processes need to be better constrained in global climate and biogeochemical models.

中文翻译：

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从 BGC-Argo 浮标数据确定的北太平洋西部的偶发俯冲斑块

摘要。与中尺度涡旋相关的俯冲是一个重要但难以观察的过程，它可以有效地将碳和氧输出到中层海带（100-1000 db）。使用覆盖西北太平洋（北纬 20-50°，东经 120-180°）的新型 BGC-Argo 数据集，我们使用溶解氧和辛辣度（一种水体标记）的异常来识别偶发俯冲的印记。2008 年至 2019 年期间，这些俯冲斑块占总剖面 (7,120) 的 4.0% (288)，主要位于 3 月至 8 月期间的黑潮延伸区域 (70.6%)。与在高纬度地区观察到的涡旋俯冲过程不同，这些偶发事件中大约有一半 (52%) 注入了低于年度永久温跃层深度 (450 db) 的富含碳和氧的水，> 20% 发生在 600 db 以上的深度。^-2 天^-1和 175 至 417 mg O ₂  m ^-2 天^-1。由于该地区的生物重力沉降和氧气通风，这些中尺度事件将显着增加碳去除量，这两者都有助于支持中层生物的营养和代谢需求。该地区涡动能增加的气候驱动模式意味着这些过程的规模将在未来增长，这意味着这些意外有效的小规模俯冲过程需要在全球气候和生物地球化学模型中得到更好的约束。