Liao, FanglouLiang, XinfengLi, YunSpall, Michael2022-04-062022-04-062022-03-03Liao, F., Liang, X., Li, Y., & Spall, M. (2022). Hidden upwelling systems associated with major western boundary currents. Journal of Geophysical Research: Oceans, 127, e2021JC017649. https://doi.org/10.1029/2021JC0176492169-9291https://udspace.udel.edu/handle/19716/30759An edited version of this paper was published by AGU. Copyright 2022 American Geophysical Union. This article was originally published in Journal of Geophysical Research: Oceans. The version of record is available at: https://doi.org/10.1029/2021JC017649Western boundary currents (WBCs) play an essential role in regulating global climate. In contrast to their widely examined horizontal motions, less attention has been paid to vertical motions associated with WBCs. Here, we examine vertical motions associated with the major WBCs by analyzing vertical velocity from five ocean synthesis products and one eddy-resolving ocean simulation. These data reveal robust and intense subsurface upwelling systems, which are primarily along isopycnal surfaces, in five major subtropical WBC systems. These upwelling systems are part of basin-scale overturning circulations and are likely driven by meridional pressure gradients along the western boundary. Globally, the WBC upwelling contributes significantly to the vertical transport of water mass and ocean properties and is an essential yet overlooked branch of the global ocean circulation. In addition, the WBC upwelling intersects the oceanic euphotic and mixed layers, and thus likely plays an important role in ocean biological and chemical processes by transporting nutrients, carbon and other tracers vertically inside the ocean. This study calls for more research into the dynamics of the WBC upwelling and their role in the ocean and climate systems. Plain Language Summary: This study shows that intense upwelling systems exist along the major western boundary currents (WBCs) around the global ocean. In contrast to other well-known oceanic upwelling systems (e.g., equatorial, coastal upwelling), these WBC upwelling systems, which are essential branches of the global ocean circulation, have been largely unrecognized in the literature. This intense upwelling and the associated overturning circulation in the subtropical ocean basins can transport nutrients, carbon, and heat inside the ocean, and consequently act as an important yet unexplored route through which the oceanic biological, chemical, and physical processes, and consequently the climate system, will be affected. This study calls for more research into the dynamics of the WBC upwelling and its role in the ocean and climate systems.en-USwestern boundary currentupwellingoverturning circulationocean vertical transportocean synthesis productsocean vertical velocityArticle