Relationship between the path of the Kuroshio in the south of Japan and the path of the Kuroshio Extension in the east

2011 ◽  
Vol 68 (1) ◽  
pp. 219-225 ◽  
Author(s):  
Shusaku Sugimoto ◽  
Kimio Hanawa
Keyword(s):  
Kuroshio Extension ◽  
The South ◽  
South Of Japan ◽  
The Kuroshio

scholarly journals Influence of Kuroshio Path Variation South of Japan on Formation of Subtropical Mode Water

2014 ◽  
Vol 44 (4) ◽  
pp. 1065-1077 ◽  
Author(s):  
Shusaku Sugimoto ◽  
Kimio Hanawa
Keyword(s):  
Kuroshio Extension ◽  
Potential Temperature ◽  
Late Summer ◽  
Northwestern Part ◽  
North Pacific Subtropical Gyre ◽  
Mode Water ◽  
Subtropical Mode Water ◽  
Shikoku Basin ◽  
South Of Japan ◽  
The Kuroshio

Abstract Distributions of subtropical mode water (STMW) in the northwestern part of the North Pacific Subtropical Gyre were investigated, using temperature–salinity profiles from 2005 to 2011, with particular reference to the Kuroshio meander and non-meander path states, south of Japan. In spring of meander years, warm STMW with a potential temperature of 19°–20°C (potential density anomaly of 24.6–24.9 kg m−3) was found in the Shikoku Basin, whereas cold STMW below 19°C was distributed throughout the southern region of Japan in non-meander years. The warm STMW was formed in a spatially isolated and warm winter mixed layer (ML) in the Shikoku Basin, where a local recirculation developed in association with the Kuroshio meander path; both the absence of horizontal mixing with a cold ML south of the Kuroshio Extension because of the spatially isolated ML and an increase in horizontal heat advection due to the westward flow associated with this local recirculation caused the ML warming in the Shikoku Basin. After the spring shoaling of the ML, the warm STMW was preserved under the seasonal pycnocline until midsummer at a depth of 100–250 dbar; its thickness was approximately half that of the cold STMW in the Shikoku Basin in non-meander years. The warm STMW was rapidly eroded between the late summer and the following winter.

scholarly journals A Kuroshio Extension System Model Study: Decadal Chaotic Self-Sustained Oscillations

2006 ◽  
Vol 36 (8) ◽  
pp. 1605-1625 ◽  
Author(s):  
Stefano Pierini
Keyword(s):  
Decadal Variability ◽  
Kuroshio Extension ◽  
Low Frequency ◽  
Internal Oscillation ◽  
Extension System ◽  
Model Study ◽  
Low Frequency Variability ◽  
South Of Japan ◽  
Altimetric Measurements ◽  
The Kuroshio

Abstract A model study of the Kuroshio Extension system, in which forcing is provided by a time-independent climatological wind, yields a mean meandering path and a decadal variability of the jet in significant agreement with in situ and altimetric measurements. A reduced-gravity primitive equation ocean model is implemented in a box spanning the whole North Pacific, including a schematic coastline at the western side, and an analytical wind forcing is determined according to the ECMWF and Comprehensive Ocean–Atmosphere Data Set (COADS) climatologies. The modeled time-averaged Kuroshio Extension shows meanders, northern and southern recirculation regions, and a jet penetration that are in good agreement with the corresponding observed climatological features. This result suggests that intrinsic nonlinear mechanisms are likely to play a major role in determining the meander pattern of the mean flow. The internal low-frequency variability is found to be a chaotic bimodal self-sustained oscillation between an energetic meandering state and a much weaker state with a reduced zonal penetration of the jet. These high and low energy states are found to be very similar to the “elongated” and “contracted” modes of the Kuroshio Extension detected through altimetric measurements; moreover, the characteristic period (of around 10 yr), flow patterns, and transition details of a typical bimodal cycle are found to be in significant agreement with altimeter observations for the period 1992–2004. A complex dynamical mechanism supporting this internal oscillation, and involving the bimodal behavior of the Kuroshio south of Japan, is proposed and discussed. On the basis of these modeling results and of their validation with altimeter data, it is hypothesized that the observed bimodal decadal variability of the Kuroshio Extension is basically due to a self-sustained internal oscillation related to the instability of the Kuroshio south of Japan without any crucial intervention of wind-driven Sverdrup transport fluctuations and of topographic interactions, although such effects certainly play an important role in shaping the finer structure of Kuroshio Extension changes. Finally, in a preliminary analysis of the variability in the framework of nonlinear dynamical systems theory it is suggested that the strange attractor corresponding to the modeled low-frequency variability is associated with a homoclinic orbit produced by a global bifurcation; moreover, transitions between oscillations of different character found for slightly different values of the lateral eddy viscosity and forcing amplitude are conjectured to be due to heteroclinic connections.

Cold air outbreak over the Kuroshio extension region

OCEANS 2009 ◽  
2009 ◽  
Author(s):  
T. G. Jensen ◽  
T. Campbell ◽  
T. A. Smith ◽  
R. J. Small ◽  
R. Allard
Keyword(s):  
Kuroshio Extension ◽  
Cold Air ◽  
Cold Air Outbreak ◽  
The Kuroshio ◽  
Kuroshio Extension Region

scholarly journals Variability of the nutrient stream near Kuroshio's origin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chen-Tung Arthur Chen ◽  
Ting-Hsuan Huang ◽  
Chi-Hsuan Wu ◽  
Haiyan Yang ◽  
Xinyu Guo
Keyword(s):  
Pacific Ocean ◽  
Continental Shelf ◽  
East China Sea ◽  
Kuroshio Extension ◽  
Subsurface Water ◽  
East China ◽  
The East China Sea ◽  
High Productivity ◽  
China Sea ◽  
The Kuroshio

AbstractThe Kuroshio—literally “the Black Stream”—is the most substantial current in the Pacific Ocean. It was called the Black Stream because this oligotrophic current is so nutrient-poor in its euphotic zone that the water appears black without the influence of phytoplankton and the associated, often colored dissolved organic matter. Yet, below the euphotic layer, nutrient concentrations increase with depth while current speed declines. Consequently, a core of maximum nutrient flux, the so-called nutrient stream, develops at a depth of roughly between 200 and 800 m. This poorly studied nutrient stream transports nutrients to and supports high productivity and fisheries on the East China Sea continental shelf; it also transports nutrients to and promotes increased productivity and fisheries in the Kuroshio Extension and the subarctic Pacific Ocean. Three modes of the Kuroshio nutrient stream are detected off SE Taiwan for the first time: one has a single-core; one has two cores that are apparently separated by the ridge at 120.6–122° E, and one has two cores that are separated by a southward flow above the ridge. More importantly, northward nutrient transports seem to have been increasing since 2015 as a result of a 30% increase in subsurface water transport, which began in 2013. Such a nutrient stream supports the Kuroshio's high productivity, such as on the East China Sea continental shelf and in the Kuroshio Extension SE of Japan.

Short-range prediction experiments of the Kuroshio path variabilities south of Japan

2006 ◽  
Vol 56 (5-6) ◽  
pp. 607-623 ◽  
Author(s):  
Norihisa Usui ◽  
Hiroyuki Tsujino ◽  
Yosuke Fujii ◽  
Masafumi Kamachi
Keyword(s):  
Short Range ◽  
Kuroshio Path ◽  
South Of Japan ◽  
The Kuroshio

A Positive Feedback Process Related to the Rapid Development of an Extratropical Cyclone over the Kuroshio/Kuroshio Extension

2018 ◽  
Vol 146 (2) ◽  
pp. 417-433 ◽  
Author(s):  
Hidetaka Hirata ◽  
Ryuichi Kawamura ◽  
Masaya Kato ◽  
Taro Shinoda
Keyword(s):  
Water Vapor ◽  
Positive Feedback ◽  
Heat Supply ◽  
Rapid Development ◽  
Kuroshio Extension ◽  
Heat Fluxes ◽  
Latent Heating ◽  
Sensible Heat ◽  
Feedback Process ◽  
The Kuroshio

Abstract The active roles of sensible heat supply from the Kuroshio/Kuroshio Extension in the rapid development of an extratropical cyclone, which occurred in the middle of January 2013, were examined by using a regional cloud-resolving model. In this study, a control experiment and three sensitivity experiments without sensible and latent heat fluxes from the warm currents were conducted. When the cyclone intensified, sensible heat fluxes from these currents become prominent around the cold conveyor belt (CCB) in the control run. Comparisons among the four runs revealed that the sensible heat supply facilitates deepening of the cyclone’s central pressure, CCB development, and enhanced latent heating over the bent-back front. The sensible heat supply enhances convectively unstable conditions within the atmospheric boundary layer along the CCB. The increased convective instability is released by the forced ascent associated with frontogenesis around the bent-back front, eventually promoting updraft and resultant latent heating. Additionally, the sensible heating leads to an increase in the water vapor content of the saturated air related to the CCB through an increase in the saturation mixing ratio. This increased water vapor content reinforces the moisture flux convergence at the bent-back front, contributing to the activation of latent heating. Previous research has proposed a positive feedback process between the CCB and latent heating over the bent-back front in terms of moisture supply from warm currents. Considering the above two effects of the sensible heat supply, this study revises the positive feedback process.

scholarly journals On the Relationship between Synoptic Wintertime Atmospheric Variability and Path Shifts in the Gulf Stream and the Kuroshio Extension

2009 ◽  
Vol 22 (12) ◽  
pp. 3177-3192 ◽  
Author(s):  
Terrence M. Joyce ◽  
Young-Oh Kwon ◽  
Lisan Yu
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Gulf Stream ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Western Boundary ◽  
Atmospheric Variability ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

Abstract Coherent, large-scale shifts in the paths of the Gulf Stream (GS) and the Kuroshio Extension (KE) occur on interannual to decadal time scales. Attention has usually been drawn to causes for these shifts in the overlying atmosphere, with some built-in delay of up to a few years resulting from propagation of wind-forced variability within the ocean. However, these shifts in the latitudes of separated western boundary currents can cause substantial changes in SST, which may influence the synoptic atmospheric variability with little or no time delay. Various measures of wintertime atmospheric variability in the synoptic band (2–8 days) are examined using a relatively new dataset for air–sea exchange [Objectively Analyzed Air–Sea Fluxes (OAFlux)] and subsurface temperature indices of the Gulf Stream and Kuroshio path that are insulated from direct air–sea exchange, and therefore are preferable to SST. Significant changes are found in the atmospheric variability following changes in the paths of these currents, sometimes in a local fashion such as meridional shifts in measures of local storm tracks, and sometimes in nonlocal, broad regions coincident with and downstream of the oceanic forcing. Differences between the North Pacific (KE) and North Atlantic (GS) may be partly related to the more zonal orientation of the KE and the stronger SST signals of the GS, but could also be due to differences in mean storm-track characteristics over the North Pacific and North Atlantic.

scholarly journals Influential Role of Moisture Supply from the Kuroshio/Kuroshio Extension in the Rapid Development of an Extratropical Cyclone

2015 ◽  
Vol 143 (10) ◽  
pp. 4126-4144 ◽  
Author(s):  
Hidetaka Hirata ◽  
Ryuichi Kawamura ◽  
Masaya Kato ◽  
Taro Shinoda
Keyword(s):  
Diabatic Heating ◽  
Rapid Development ◽  
Kuroshio Extension ◽  
Lower Troposphere ◽  
Active Role ◽  
Conveyor Belt ◽  
Synoptic Scale ◽  
Warm Front ◽  
The Kuroshio

Abstract This study focused on an explosive cyclone migrating along the southern periphery of the Kuroshio/Kuroshio Extension in the middle of January 2013 and examined how those warm currents played an active role in the rapid development of the cyclone using a high-resolution coupled atmosphere–ocean regional model. The evolutions of surface fronts of the simulated cyclone resemble the Shapiro–Keyser model. At the time of the maximum deepening rate, strong mesoscale diabatic heating areas appear over the bent-back front and the warm front east of the cyclone center. Diabatic heating over the bent-back front and the eastern warm front is mainly induced by the condensation of moisture imported by the cold conveyor belt (CCB) and the warm conveyor belt (WCB), respectively. The dry air parcels transported by the CCB can receive large amounts of moisture from the warm currents, whereas the very humid air parcels transported by the WCB can hardly be modified by those currents. The well-organized nature of the CCB plays a key role not only in enhancing surface evaporation from the warm currents but also in importing the evaporated vapor into the bent-back front. The imported vapor converges at the bent-back front, leading to latent heat release. The latent heating facilitates the cyclone’s development through the production of positive potential vorticity in the lower troposphere. Its deepening can, in turn, reinforce the CCB. In the presence of a favorable synoptic-scale environment, such a positive feedback process can lead to the rapid intensification of a cyclone over warm currents.

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