scholarly journals Water Column Profiles of Dissolved Inorganic Radiocarbon for the Kuroshio Region, Offshore of the Southern Japanese Coast

Radiocarbon ◽  
2011 ◽  
Vol 53 (4) ◽  
pp. 679-690 ◽  
Author(s):  
Tatsuya Tsuboi ◽  
Hiroshi Iwata ◽  
Hideki Wada ◽  
Hiroyuki Matsuzaki ◽  
Rumi Sohrin ◽  
...  
Keyword(s):  
Water Column ◽  
Intermediate Layer ◽  
Large Meander ◽  
Study Region ◽  
Japanese Coast ◽  
Kuroshio Large Meander ◽  
The Kuroshio ◽  
Kuroshio Region

We present the water column profiles (surface to 2000 m depth) for dissolved inorganic radiocarbon (14CDIC) from 2 stations in the Kuroshio region including the Kuroshio large meander (LM) of 2004–2005. Surprisingly, the Δ14CDIC value varied up to 125‰ in the intermediate layer, especially near 600 m depth. In addition, the Δ14CDIC value was approximately − 150‰ at 200 m depth at the northern station of Kuroshio in August 2005. This value is ∼100‰ less than other Δ14CDIC values for the same depth. In comparison, the Δ14CDIC water column profiles for the southern station of Kuroshio and GEOSECS station 224 decrease down to 600 m depth and were similar below 600 m depth. Our results suggest that strong upwelling associated with the Kuroshio LM has a powerful influence on the Δ14CDIC water column profiles in the study region.

scholarly journals Atmospheric Effects of the Kuroshio Large Meander during 2004–05*

2010 ◽  
Vol 23 (17) ◽  
pp. 4704-4715 ◽  
Author(s):  
Haiming Xu ◽  
Hiroki Tokinaga ◽  
Shang-Ping Xie
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Atmospheric Effects ◽  
Water Pool ◽  
Large Meander ◽  
Cool Water ◽  
Japanese Coast ◽  
Kuroshio Large Meander ◽  
The Kuroshio

Abstract In the summer of 2004, the Kuroshio took a large meander path south of Japan for the first time since 1991, and this large meander event persisted until the next summer. Satellite observations and numerical model simulations are used to study the effect of this large meander event on the atmosphere. The large meander leaves a cool water pool between the Kuroshio and Japanese coast. Sea surface temperature (SST) in the cool water pool is about 2°–3°C colder than the surroundings during winter and spring, whereas the SST signature substantially weakens in summer. A local reduction of wind speed is found over the cool water pool, and the positive SST–wind speed correlation is indicative of ocean forcing of the atmosphere. Cloud liquid water (CLW) content and precipitation also decrease over the cool SST pool. A regional atmospheric model successfully simulates atmospheric response to the Kuroshio large meander. The model experiments suggest that the reduced surface wind speed and precipitation are due to the large meander-induced SST cooling. Analysis of the surface perturbation momentum budgets shows the importance of the pressure adjustment mechanism in surface wind response to the cold SST anomalies.

scholarly journals Phytoplankton Increase Along the Kuroshio Due to the Large Meander

2021 ◽  
Vol 8 ◽  
Author(s):  
Daniel Andres Lizarbe Barreto ◽  
Ricardo Chevarria Saravia ◽  
Takeyoshi Nagai ◽  
Takafumi Hirata
Keyword(s):  
Chlorophyll A ◽  
Mixed Layer Depth ◽  
Local Environment ◽  
Trophic Levels ◽  
Large Meander ◽  
The Mean ◽  
Western Side ◽  
The Kuroshio ◽  
Cold Core ◽  
Kuroshio Region

The Kuroshio Large Meander (LM) is known to be highly aperiodic and can last from 1 to 10 years. Since a stationary cold core formed between the Kuroshio and the southern coast of Japan off Enshu-Nada and approaching warm saltier water on the eastern side of the LM changes the local environment drastically, many commercially valuable fish species distribute differently from the non-LM period, impacting local fisheries. Despite this importance of the LM, the influences of the LM on the low trophic levels such as phytoplankton and zooplankton have still been unclear. In this study, satellite daily sea surface chlorophyll data are analyzed in relation to the LM. The results show positive anomalies of the chlorophyll-a concentration along the Kuroshio path during the LM periods, 2004–2005 and 2017–2019, from the upstream off Shikoku to the downstream (140°E). These positive anomalies are started by the triggering meander generated off south of Kyushu, which then slowly propagates to the downstream LM region in both the LM periods. Even though the detailed patterns along the Kuroshio region in the two LM periods were different, similar formations of the positive anomalies on the western side of the LM with shallower mixed layer depth are observed. Furthermore, we found clear relationships between the minimum distance from several stations along the coast to the Kuroshio axis and the mean chlorophyll-a anomaly, with significant correlations with the distance from different stations.

The Nonlinear Optimal Triggering Perturbation of the Kuroshio Large Meander and Its Evolution in a Regional Ocean Model

2018 ◽  
Vol 48 (8) ◽  
pp. 1771-1786 ◽  
Author(s):  
Xia Liu ◽  
Mu Mu ◽  
Qiang Wang
Keyword(s):  
Ocean Model ◽  
Ocean Modeling ◽  
Cyclonic Eddy ◽  
Regional Ocean Modeling System ◽  
Large Meander ◽  
Optimal Perturbation ◽  
Nonlinear Advection ◽  
Kuroshio Large Meander ◽  
Opposing Effects ◽  
The Kuroshio

AbstractBased on the Regional Ocean Modeling System (ROMS) and the conditional nonlinear optimal perturbation (CNOP) method, we explore the nonlinear optimal triggering perturbation of the Kuroshio large meander (LM) and its evolution, and reveal the role of nonlinear physical processes in the formation of the LM path. The results show that the large amplitudes of the perturbations are mainly located in the upper 2000 m in the southeastern area of Kyushu (29°–32°N, 131°–134°E), where the eastward propagation of the cold anomaly is vital to the formation of the LM path. By analyzing the depth-integrated vorticity equation of the perturbation, we find that linear advection, namely, the interaction between the perturbation and the reference field, tends to move the cyclonic eddy induced by the optimal triggering perturbation eastward, while the nonlinear advection associated with the interaction of perturbations tends to move the cyclonic eddy westward. The opposing effects of the nonlinear advection and the linear advection slow the eastward movement of the cyclonic eddy so that the eddy has a chance to effectively develop, eventually leading to the formation of the Kuroshio LM path.

scholarly journals An Objective Method for Probabilistic Forecasting of Multimodal Kuroshio States using Ensemble Simulation and Machine Learning

2020 ◽  
Vol 50 (11) ◽  
pp. 3189-3204
Author(s):  
Kunihiro Aoki ◽  
Yasumasa Miyazawa ◽  
Tsutomu Hihara ◽  
Toru Miyama
Keyword(s):  
Machine Learning ◽  
Baroclinic Instability ◽  
Mixture Distribution ◽  
Gaussian Mixture ◽  
Distribution Model ◽  
Probabilistic Forecasting ◽  
Large Meander ◽  
Mixture Distribution Model ◽  
The Kuroshio ◽  
Kuroshio Region

AbstractThis paper presents a method for detecting the ensemble means, spreads, and occurrence probabilities for each of the multiple Kuroshio states. This is accomplished by classifying the forecasts of the ensemble members with a Gaussian mixture distribution model, a machine learning method. Ensemble simulations with 80 members are conducted to reproduce possible occurrences of the multiple Kuroshio states, targeting the large meander event in 2017. To test its performance, first, the method is applied for the southernmost latitude, a conventional index that represents meander intensity. The results show that the Kuroshio initially taking the nearshore nonlarge meander state bifurcates into the large meander and offshore nonlarge meander states, which occur with similar probabilities. Both developments are accompanied by positive potential energy extraction rates, consistent with baroclinic instability. As a more objective approach, the method is then applied for the dominant modes derived from empirical orthogonal function (EOF) analysis of the sea surface height field in the entire Kuroshio region. Importantly, almost identical results can be achieved. In particular, the bimodality between the large meander and nonlarge meander is shown to appear on the axis of the first EOF mode. From a mathematical perspective, this mode can be interpreted as the singular vector which grows most rapidly following the time-evolution operator. Finally, the multimodality of the Kuroshio is reinterpreted as a phase transition phenomenon where the nearshore nonlarge meander constitutes the basic state.

scholarly journals Application of singular vector analysis to the Kuroshio large meander

2008 ◽  
Vol 113 (C7) ◽  
Author(s):  
Yosuke Fujii ◽  
Hiroyuki Tsujino ◽  
Norihisa Usui ◽  
Hideyuki Nakano ◽  
Masafumi Kamachi
Keyword(s):  
Singular Vector ◽  
Vector Analysis ◽  
Large Meander ◽  
Kuroshio Large Meander ◽  
The Kuroshio

scholarly journals Blocking of the Kuroshio Large Meander by Baroclinic Interaction with the Izu Ridge

2006 ◽  
Vol 36 (11) ◽  
pp. 2042-2059 ◽  
Author(s):  
Humio Mitsudera ◽  
Bunmei Taguchi ◽  
Takuji Waseda ◽  
Yasushi Yoshikawa
Keyword(s):  
Rossby Waves ◽  
Western Slope ◽  
Large Meander ◽  
Kuroshio Large Meander ◽  
Topographic Rossby Waves ◽  
The Kuroshio ◽  
Izu Ridge ◽  
Sloping Bottom

Abstract This paper discusses the role of the Izu Ridge in blocking the Kuroshio large meander from propagating eastward across the ridge. It is shown that a combination of the sloping bottom with baroclinicity in the Kuroshio flow is important for blocking of the large meander. It produces a cyclonic torque over the western slope of the ridge when the large meander impinges upon it. That is, the cyclonic torque is formed ahead of the large meander, which results in blocking and amplification of the meander upstream of the Izu Ridge. The baroclinicity of the Kuroshio over the ridge is caused by baroclinic topographic Rossby waves generated when the large meander encounters the ridge.

scholarly journals Response of extratropical cyclone activity to the Kuroshio large meander in northern winter

2013 ◽  
Vol 40 (11) ◽  
pp. 2851-2855 ◽  
Author(s):  
Masamitsu Hayasaki ◽  
Ryuichi Kawamura ◽  
Masato Mori ◽  
Masahiro Watanabe
Keyword(s):  
Extratropical Cyclone ◽  
Cyclone Activity ◽  
Large Meander ◽  
Kuroshio Large Meander ◽  
Northern Winter ◽  
The Kuroshio
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