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The Pacific Equatorial Undercurrent in Three Generations of Global Climate Models and Glider Observations
Author(s) -
Karnauskas Kristopher B.,
Jakoboski Julie,
Johnston T. M. Shaun,
Owens W. Brechner,
Rudnick Daniel L.,
Todd Robert E.
Publication year - 2020
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2020jc016609
Subject(s) - climatology , oceanography , glider , environmental science , stratification (seeds) , general circulation model , upwelling , ocean current , marine ecosystem , climate model , ecosystem , geology , climate change , ecology , biology , seed dormancy , botany , germination , dormancy , marine engineering , engineering
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.