Interannual-decadal variability of wintertime mixed layer depths in the North Pacific detected by an ensemble of ocean syntheses
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Author(s)
Toyoda, Takahiro
Fujii, Yosuke
Kuragano, Tsurane
Kosugi, Naohiro
Sasano, Daisuke
Kamachi, Masafumi
Ishikawa, Yoichi
Masuda, Shuhei
Sato, Kanako
Awaji, Toshiyuki
Date Issued
August 2015
Journal
Climate Dynamics
Publisher
Springer Berlin Heidelberg
Citation
Toyoda, Takahiro et al. “Interannual-Decadal Variability of Wintertime Mixed Layer Depths in the North Pacific Detected by an Ensemble of Ocean Syntheses.” Climate Dynamics (2015): n. pag.
Version
Author's final manuscript
Abstract
The interannual-decadal variability of the wintertime mixed layer depths (MLDs) over the North Pacific is investigated from an empirical orthogonal function (EOF) analysis of an ensemble of global ocean reanalyses. The first leading EOF mode represents the interannual MLD anomalies centered in the eastern part of the central mode water formation region in phase opposition with those in the eastern subtropics and the central Alaskan Gyre. This first EOF mode is highly correlated with the Pacific decadal oscillation index on both the interannual and decadal time scales. The second leading EOF mode represents the MLD variability in the subtropical mode water (STMW) formation region and has a good correlation with the wintertime West Pacific (WP) index with time lag of 3 years, suggesting the importance of the oceanic dynamical response to the change in the surface wind field associated with the meridional shifts of the Aleutian Low. The above MLD variabilities are in basic agreement with previous observational and modeling findings. Moreover the reanalysis ensemble provides uncertainty estimates. The interannual MLD anomalies in the first and second EOF modes are consistently represented by the individual reanalyses and the amplitudes of the variabilities generally exceed the ensemble spread of the reanalyses. Besides, the resulting MLD variability indices, spanning the 1948–2012 period, should be helpful for characterizing the North Pacific climate variability. In particular, a 6-year oscillation including the WP teleconnection pattern in the atmosphere and the oceanic MLD variability in the STMW formation region is first detected.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1007/s00382-015-2762-3
