Argo Reveals the Scales and Provenance of Equatorial Island Upwelling Systems
Argo Reveals the Scales and Provenance of Equatorial Island Upwelling Systems
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DOI：
10.1029/2022gl098744
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发表时间：
2022-08
影响因子：
5.2
通讯作者：
K. Karnauskas;D. Giglio
中科院分区：
文献类型：
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作者：
K. Karnauskas;D. Giglio
赤道岛屿具有独特的海洋学特征，包括其西侧紧邻区域的凉爽海面温度和高生产力。长期以来人们一直假设地形上升流是造成这些特征的原因——即赤道逆流（EUC）在向东流动时被岛屿向上偏转。利用阿尔戈（Argo）浮标22年的原位测量数据，我们首次直接观测到这一过程在赤道太平洋的两个主要群岛上持续发生。阿尔戈测量数据解析出了赤道逆流深度处垂直辐散的清晰次表层热指纹，该指纹局限在吉尔伯特群岛（约175°E）和加拉帕戈斯群岛（约90°W）100公里范围内。加拉帕戈斯群岛的这一信号在高分辨率海洋再分析中得到了很好的重现，从而能够估算出平衡赤道逆流在岛屿处纬向辐合的垂直速度。这种对支撑如此重要的热带生态系统的物理机制的更清晰认识，对模拟和预测它们的策略具有影响。
Equatorial islands have distinct oceanographic signatures, including cool sea surface temperature and high productivity immediately to their west. It has long been hypothesized that topographic upwelling is responsible for such characteristics—upward deflection by the islands of the eastward‐flowing equatorial undercurrent (EUC). Using 22 years of in situ measurements by Argo, we provide the first direct observations of this process occurring with consistency at two prominent archipelagos in the equatorial Pacific. Argo measurements resolve a clear subsurface thermal fingerprint of vertical divergence at the depth of the EUC, confined to within 100 km of both the Gilbert (∼175°E) and Galápagos Islands (∼90°W). This signal at the Galápagos is well‐reproduced by a high‐resolution ocean reanalysis, enabling the estimation of vertical velocities balancing the zonal convergence of the EUC upon the islands. This sharpened view of the physics underpinning such important tropical ecosystems has implications for strategies to model and predict them.