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are well suited to detect their variability in a systematic way. The present study has three objectives. The first is to describe the time-varying NEC bifurcation along the Philippine coast based on the 17-yr satellite altimeter data. Well-defined, quasi-decadal changes with a peak-to-peak amplitude exceeding 5° latitude are detected. The second objective is to examine the dynamics underlying the observed bifurcation changes. This is pursued by adopting a 1 ½-layer reduced-gravity model forced by
are well suited to detect their variability in a systematic way. The present study has three objectives. The first is to describe the time-varying NEC bifurcation along the Philippine coast based on the 17-yr satellite altimeter data. Well-defined, quasi-decadal changes with a peak-to-peak amplitude exceeding 5° latitude are detected. The second objective is to examine the dynamics underlying the observed bifurcation changes. This is pursued by adopting a 1 ½-layer reduced-gravity model forced by
–SEC region. These broad patterns affecting South Pacific Subtropical Gyre circulation could manifest in the STCC–SEC region, altering the state of the ocean and leading to enhanced eddy activity. An increasingly long record of observations in the region allows us to improve our understanding of the basic state of the STCC–SEC region and the slow, decadal variability from this mean state. This paper works to expand upon those previous findings by providing a detailed description of the basic state of the
–SEC region. These broad patterns affecting South Pacific Subtropical Gyre circulation could manifest in the STCC–SEC region, altering the state of the ocean and leading to enhanced eddy activity. An increasingly long record of observations in the region allows us to improve our understanding of the basic state of the STCC–SEC region and the slow, decadal variability from this mean state. This paper works to expand upon those previous findings by providing a detailed description of the basic state of the
1. Introduction The Bohai, Yellow, and East China Seas ( Fig. 1 ) are shallow marginal seas enclosed by East China, the Korean Peninsula, and Japan with open connections to the northwest Pacific, the South China Sea, and the Sea of Japan ( Su 1998 ). In addition to local atmospheric forcing and freshwater runoff, the large-scale atmospheric and oceanic variability, such as the Pacific decadal oscillation (PDO) may impact the seasonal and longer-term hydrography and circulation variability in
1. Introduction The Bohai, Yellow, and East China Seas ( Fig. 1 ) are shallow marginal seas enclosed by East China, the Korean Peninsula, and Japan with open connections to the northwest Pacific, the South China Sea, and the Sea of Japan ( Su 1998 ). In addition to local atmospheric forcing and freshwater runoff, the large-scale atmospheric and oceanic variability, such as the Pacific decadal oscillation (PDO) may impact the seasonal and longer-term hydrography and circulation variability in
figure are Izu–Ogasawara Ridge (IO), Shatsky Rise (SR), and Emperor Seamounts (ES). (b) Long-term mean eddy kinetic energy (colored shading; J m −3 ). The black line shows the jet axis (100-cm isobath of the sea surface height). Significant decadal variability has been observed in the Kuroshio Extension, reflected by multiple indices such as the regional sea surface height (SSH) anomalies, jet strength, latitudinal position, and pathlength, to name a few ( Qiu and Chen 2005 ). During the past decade
figure are Izu–Ogasawara Ridge (IO), Shatsky Rise (SR), and Emperor Seamounts (ES). (b) Long-term mean eddy kinetic energy (colored shading; J m −3 ). The black line shows the jet axis (100-cm isobath of the sea surface height). Significant decadal variability has been observed in the Kuroshio Extension, reflected by multiple indices such as the regional sea surface height (SSH) anomalies, jet strength, latitudinal position, and pathlength, to name a few ( Qiu and Chen 2005 ). During the past decade
1. Introduction The existence of decadal-scale variability in the Pacific Ocean is now well documented, and it affects the climate and fisheries of the neighboring regions to a significant extent (e.g., Trenberth and Hurrell 1994 ; Zhang et al. 1997 ; Mantua et al. 1997 ). This Pacific decadal variability (PDV) in the North Pacific is usually described by the Pacific decadal oscillation (PDO) index ( Mantua and Hare 2002 ), which is quite energetic in the interdecadal spectral range. There
1. Introduction The existence of decadal-scale variability in the Pacific Ocean is now well documented, and it affects the climate and fisheries of the neighboring regions to a significant extent (e.g., Trenberth and Hurrell 1994 ; Zhang et al. 1997 ; Mantua et al. 1997 ). This Pacific decadal variability (PDV) in the North Pacific is usually described by the Pacific decadal oscillation (PDO) index ( Mantua and Hare 2002 ), which is quite energetic in the interdecadal spectral range. There
March–April 2009, are presented here to extend the record of the decadal variability in the South Atlantic at 24°S. Salinities from three cruises from 1958, 1983, and 2009 ( Fig. 2 ) are compared on neutral density surfaces. Practical salinity is used rather than absolute salinity for ease of comparison with previous studies. Thermocline waters will be shown to have increased in salinity from 1958 to 1983 and freshened from 1983 to 2009. The influence of inflow from the Indian Ocean is estimated by
March–April 2009, are presented here to extend the record of the decadal variability in the South Atlantic at 24°S. Salinities from three cruises from 1958, 1983, and 2009 ( Fig. 2 ) are compared on neutral density surfaces. Practical salinity is used rather than absolute salinity for ease of comparison with previous studies. Thermocline waters will be shown to have increased in salinity from 1958 to 1983 and freshened from 1983 to 2009. The influence of inflow from the Indian Ocean is estimated by
1. Introduction During the last decade, it has become evident that a large fraction of variability in the global ocean is intrinsic in the sense that no interannual-to-decadal atmospheric variability is needed to drive oceanic variability on these time scales. Studies utilizing ocean general circulation models (OGCMs) have shown this intrinsic variability to manifest itself in sea surface height (SSH) variance ( Combes and Di Lorenzo 2007 ; Penduff et al. 2011 ; Sérazin et al. 2015 ) as well
1. Introduction During the last decade, it has become evident that a large fraction of variability in the global ocean is intrinsic in the sense that no interannual-to-decadal atmospheric variability is needed to drive oceanic variability on these time scales. Studies utilizing ocean general circulation models (OGCMs) have shown this intrinsic variability to manifest itself in sea surface height (SSH) variance ( Combes and Di Lorenzo 2007 ; Penduff et al. 2011 ; Sérazin et al. 2015 ) as well
1. Introduction The ocean water-mass variability is intimately linked to the atmospheric changes as they are imprinted at the ocean surface by the natural climate modulation and anthropogenic forcing. Recent studies have shown that the ocean warming during the last decade has been mainly concentrated in the extratropical Southern Hemisphere ( Häkkinen et al. 2016 ; Roemmich et al. 2015 ; Kolodziejczyk et al. 2019 ). In particular, hot spots of ocean warming have been localized in the southern
1. Introduction The ocean water-mass variability is intimately linked to the atmospheric changes as they are imprinted at the ocean surface by the natural climate modulation and anthropogenic forcing. Recent studies have shown that the ocean warming during the last decade has been mainly concentrated in the extratropical Southern Hemisphere ( Häkkinen et al. 2016 ; Roemmich et al. 2015 ; Kolodziejczyk et al. 2019 ). In particular, hot spots of ocean warming have been localized in the southern
variability. J. Climate , 19 , 521 – 534 . Neelin , J. D. , and W. Weng , 1999 : Analytical prototypes for ocean–atmosphere interaction at midlatitudes. Part I: Coupled feedbacks as a sea surface temperature dependent stochastic process. J. Climate , 12 , 2037 – 2049 . Newman , M. , G. P. Compo , and M. A. Alexander , 2003a : ENSO-forced variability of the Pacific decadal oscillation. J. Climate , 16 , 3853 – 3857 . Newman , M. , P. D. Sardeshmukh , C. R. Winkler , and J
variability. J. Climate , 19 , 521 – 534 . Neelin , J. D. , and W. Weng , 1999 : Analytical prototypes for ocean–atmosphere interaction at midlatitudes. Part I: Coupled feedbacks as a sea surface temperature dependent stochastic process. J. Climate , 12 , 2037 – 2049 . Newman , M. , G. P. Compo , and M. A. Alexander , 2003a : ENSO-forced variability of the Pacific decadal oscillation. J. Climate , 16 , 3853 – 3857 . Newman , M. , P. D. Sardeshmukh , C. R. Winkler , and J
indicates the southward shift of the KE jet. Observational (e.g., Miller et al. 1998 ; Deser et al. 1999 ; Lysne and Deser 2002 ; Qiu and Chen 2005 ) and numerical studies (e.g., Seager et al. 2001 ; Taguchi et al. 2007 ) suggest that decadal variability in the KE is primary forced by basin-wide wind stress curl changes with the KE lagging by several years. Lysne and Deser (2002) showed that decadal subsurface temperature variations in the KE region are related to the 4-yr leading wind stress
indicates the southward shift of the KE jet. Observational (e.g., Miller et al. 1998 ; Deser et al. 1999 ; Lysne and Deser 2002 ; Qiu and Chen 2005 ) and numerical studies (e.g., Seager et al. 2001 ; Taguchi et al. 2007 ) suggest that decadal variability in the KE is primary forced by basin-wide wind stress curl changes with the KE lagging by several years. Lysne and Deser (2002) showed that decadal subsurface temperature variations in the KE region are related to the 4-yr leading wind stress
