Observations of the Kuroshio's barotropic and baroclinic responses to basin-wide wind forcing
MetadataShow full item record
Observations show that the Kuroshio in the East China Sea (ECS-Kuroshio) responds to the large-scale wind stress curl field at two time scales. It is argued that these two responses are related to barotropic and baroclinic modes that reach the ECS via different waveguides. Variability in the ECS-Kuroshio is assessed by comparing satellite altimetry, historical hydrography, and the Pacific Decadal Oscillation (PDO) index with the latter used as a proxy for the large-scale wind stress curl forcing. Sea level difference across the ECS-Kuroshio is positively correlated with PDO at zero lag and negatively correlated at 7 year lag. In contrast, pycnocline steepness and PDO are uncorrelated at zero lag and negatively correlated at 7 year lag. These signals in the ECS-Kuroshio, considered together with wind stress curl anomalies in the open ocean, are consistent with a barotropic response to the wind at zero lag. The barotropic response is likely forced in the central North Pacific by wind stress curl anomalies of opposite sign, one of which is centered at ECS latitudes (∼27°N) while the other sits further north. This suggests that, in general, the absolute transport at a given latitude is not simply that predicted by the Sverdrup balance along the latitude. This is a consequence of waveguides that can steer the barotropic mode across latitude lines. In contrast, the signals that lag PDO by 7 years are consistent with a baroclinic mode, which represents the ocean's time-integrated response to the wind stress curl along a single latitude band between 24°N and 27°N.
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): C04011, doi:10.1029/2010JC006863.
Showing items related by title, author, creator and subject.
Coupled atmosphere–mixed layer ocean response to ocean heat flux convergence along the Kuroshio Current Extension Kwon, Young-Oh; Deser, Clara; Cassou, Christophe (2010-01-28)The winter response of the coupled atmosphere-ocean mixed layer system to anomalous geostrophic ocean heat flux convergence in the Kuroshio Extension is investigated by means of experiments with an atmospheric general ...
The Kuroshio Extension northern recirculation gyre : profiling float measurements and forcing mechanism Qiu, Bo; Chen, Shuiming; Hacker, Peter; Hogg, Nelson G.; Jayne, Steven R.; Sasaki, Hideharu (American Meteorological Society, 2008-08)Middepth, time-mean circulation in the western North Pacific Ocean (28°–45°N, 140°–165°E) is investigated using drift information from the profiling floats deployed in the Kuroshio Extension System Study (KESS) and the ...
The Kuroshio Extension : a leading mechanism for the seasonal sea-level variability along the west coast of Japan Ma, Chao; Yang, Jiayan; Wu, Dexing; Lin, Xiaopei (2009-10-08)Sea level changes coherently along the two coasts of Japan on the seasonal time scale. AVISO satellite altimetry data and OFES (OGCM for the Earth Simulator) results indicate that the variation propagates clockwise from ...