The Equatorial Undercurrent (EUC) is a vital component of the coupled ocean‐atmosphere system in the tropical Pacific. The details of its termination near the Galápagos Islands in the eastern Pacific have an outsized importance to regional circulation and ecosystems. Subject to diverse physical processes, the EUC is also a rigorous benchmark for global climate models (GCMs). Simulations of the EUC in three generations of GCMs are evaluated relative to recent underwater glider observations along 93°W. Simulations of the EUC have improved, but a slow bias of ~36% remains in the eastern Pacific, along with a dependence on resolution. Additionally, the westward surface current is too slow, and stratification is too strong (weak) by ~50% above (within) the EUC. These biases have implications for mixing in the equatorial cold tongue. Downstream lies the Galápagos, now resolved to varying degrees by GCMs. Properly representing the Galápagos is necessary to avoid new biases as the EUC improves.

中文翻译：

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三代全球气候模式和滑翔机观测资料中的太平洋赤道暗流

赤道暗流（EUC）是热带太平洋海洋-大气耦合系统的重要组成部分。它在东太平洋加拉帕戈斯群岛附近终止的细节对区域流通和生态系统具有极其重要的意义。根据不同的物理过程，EUC还是全球气候模型（GCM）的严格基准。相对于最近在93°W处进行的水下滑翔机观测，评估了三代GCM中EUC的模拟。EUC的模拟已得到改善，但东太平洋地区仍然存在〜36％的缓慢偏差，并依赖于分辨率。此外，向西的地表电流太慢，并且分层太强（弱），比EUC高（弱）了约50％。这些偏见暗示着赤道冷舌混在一起。下游是加拉帕戈斯群岛（Galápagos），现已由GCM在不同程度上解决。随着EUC的改进，正确地代表加拉帕戈斯群岛是避免新的偏见的必要。