North and equatorial Pacific Ocean circulation in the CORE-II hindcast simulations
Journal
Ocean Modelling
Journal Volume
104
Pages
143-170
Date Issued
2016
Author(s)
Tseng, Y.-H.
Lin, H.
Chen, H.-C.
Thompson, K.
Bentsen, M.
B\\oning, C.W.
Bozec, A.
Cassou, C.
Chassignet, E.
Chow, C.H.
Danabasoglu, G.
Danilov, S.
Farneti, R.
Fogli, P.G.
Fujii, Y.
Griffies, S.M.
Ilicak, M.
Jung, T.
Masina, S.
Navarra, A.
Patara, L.
Samuels, B.L.
Scheinert, M.
Sidorenko, D.
Tsujino, H.
Valcke, S.
Voldoire, A.
Wang, Q.
Yeager, S.G.
Abstract
We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and Equatorial Pacific Ocean based on a suite of global ocean-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the Equatorial Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the equatorial transport, leading to a generally weak North Equatorial Counter Current in all models due to inaccurate CORE-II equatorial wind fields. Most models show a larger interior transport of Pacific subtropical cells than the observation due to the overestimated transport in the Northern Hemisphere likely resulting from the deep pycnocline. © 2016 Elsevier Ltd.
Subjects
CORE global ocean-ice simulations; Kuroshio; Mode water; North Pacific simulations; Subtropical cell
SDGs
Other Subjects
Atmospheric temperature; Higher order statistics; Ocean currents; Sea ice; Surface properties; Surface waters; Tropics; Equatorial Pacific Ocean; Ice simulation; Kuroshio; North Pacific; Sea surface temperature (SST); Subtropical Cell; Subtropical mode water formations; Western boundary currents; Oceanography; atmospheric forcing; equatorial dynamics; ice-ocean interaction; mixed layer; numerical model; sea ice; subtropical convergence; Kuroshio Current; Pacific Ocean; Pacific Ocean (Equatorial); Pacific Ocean (North)
Type
journal article