The Kuroshio Nutrient Transport during Winter of 2009

2013 ◽  
Vol 838-841 ◽  
pp. 2361-2365
Author(s):  
Yu Long ◽  
Xiao Hua Zhu ◽  
Xin Yu Guo
Keyword(s):  
East China Sea ◽  
Nutrient Transport ◽  
East China ◽  
Nitrate Transport ◽  
Ryukyu Islands ◽  
The East China Sea ◽  
China Sea ◽  
Subsurface Maximum ◽  
South Of Japan ◽  
The Kuroshio

To confirm Spatial variations of Kuroshio nutrient transport from the East China Sea to South of Japan, we apply an inverse method to hydrographic data from sections across the Kuroshio path from the East China Sea (Sections PN and TK) to south of Japan (Sections ASUKA and 137E) to get absolute geostrophic velocity, then the nutrient flux (velocity times concentration) and nutrient transport (integration of flux over a section) were calculated. In addition, Section OK east of the Ryukyu Islands was also examined. The nitrate flux during winter of 2009 shows a subsurface maximum core with a value of 11, 15, 7, 19,and 10 mol m-2s-1at Sections PN, TK, OK, ASUKA and 137E, respectively. The depth of subsurface maximum core is about 280, 470, 800, 200, and 470 m at Sections PN, TK, OK, ASUKA and 137E, respectively. The eastward nitrate transport is 248.6,213.3,97.7,804.3,879.0 k mol s-1at Sections PN, TK, OK, ASUKA and 137E, respectively. Comparisons between nitrate transport through Section ASUKA and the sum of transports through Sections TK and OK and nitrate transport of Section 137E, suggest that the Kuroshio recirculation south of Shikoku can significantly intensify the eastward nitrate transport by the Kuroshio and therefore plays an important role in the nitrate transport in the Kuroshio region.

scholarly journals Spatial variations in the Kuroshio nutrient transport from the East China Sea to south of Japan

2013 ◽  
Vol 10 (4) ◽  
pp. 6737-6762 ◽  
Author(s):  
X. Y. Guo ◽  
X.-H. Zhu ◽  
Y. Long ◽  
D. J. Huang
Keyword(s):  
East China Sea ◽  
East China ◽  
Nitrate Transport ◽  
The East China Sea ◽  
China Sea ◽  
Subsurface Maximum ◽  
Nitrate Flux ◽  
The Mean ◽  
South Of Japan ◽  
The Kuroshio

Abstract. Based on absolute geostrophic velocity calculated from repeated hydrographic data of 39 cruises from 2000 to 2009 and nitrate concentrations measured at the same sections from 1964 to 2011, we obtained temporally averaged nitrate flux (the product of velocity and nitrate concentration) and nitrate transport (integration of flux over a section) through 4 sections along the Kuroshio path from the East China Sea (sections PN and TK) to south of Japan (sections ASUKA and 137E). In addition, we examined section OK east of the Ryukyu Islands in order to understand the contribution of Ryukyu Current to the Kuroshio nutrient transport south of Japan. The mean nitrate flux shows a subsurface maximum core with a value of 10, 10, 11, 11, and 6 mol m–2 s–1 at sections PN, TK, ASUKA, 137E, and OK, respectively. The depth of subsurface maximum core changes among five sections and is approximately 400, 500, 500, 400, and 800 m at sections PN, TK, ASUKA, 137E, and OK respectively. The mean downstream nitrate transport is 199.3, 176.3, 909.2, 1385.5, and 341.2 kmol m–1 at sections PN, TK, ASUKA, 137E, and OK respectively. The nutrient transports at these sections suggest the presence of Kuroshio nutrient stream from its upstream region to downstream. The deep current structure of Ryukyu Current (section OK) makes it contribute more nitrate transport than the Kuroshio in the East China Sea (section TK) to the Kuroshio south of Japan. In addition, the positive difference between the downstream nitrate transport through section ASUKA and the sum of nitrate transports through sections TK and OK, as well as the positive difference of downstream nitrate transport between sections 137E and ASUKA, suggest that the Kuroshio recirculation significantly intensifies the downstream (eastward) nitrate transport by the Kuroshio.

scholarly journals Spatial variations in the Kuroshio nutrient transport from the East China Sea to south of Japan

2013 ◽  
Vol 10 (10) ◽  
pp. 6403-6417 ◽  
Author(s):  
X. Y. Guo ◽  
X.-H. Zhu ◽  
Y. Long ◽  
D. J. Huang
Keyword(s):  
East China Sea ◽  
Nitrate Concentration ◽  
East China ◽  
Nitrate Transport ◽  
The East China Sea ◽  
China Sea ◽  
Nitrate Flux ◽  
The Mean ◽  
South Of Japan ◽  
The Kuroshio

Abstract. Based on absolute geostrophic velocity, which was calculated using repeated hydrographic data of 39 cruises from 2000 to 2009 and nitrate concentrations measured in the same areas from 1964 to 2009, we obtained the temporally averaged nitrate flux (the product of velocity and nitrate concentration) and nitrate transport (integration of flux over one section) of four sections across the Kuroshio from the East China Sea (sections PN and TK) to an area south of Japan (sections ASUKA and 137E). In addition, we examined section OK east of the Ryukyu Islands in order to understand how the Ryukyu Current contributes to the transport of nutrients by the Kuroshio south of Japan. The mean nitrate flux shows a subsurface maximum core with values of 9.6, 10.6, 11.2, 10.5, and 5.7 mol m−2 s−1 at sections PN, TK, ASUKA, 137E, and OK, respectively. The depth of the subsurface maximum core changes among these five sections and is approximately 400, 500, 500, 400, and 800 m at sections PN, TK, ASUKA, 137E, and OK, respectively. The mean downstream nitrate transport is 204.8, 165.8, 879.3, 1230.4, and 338.6 kmol s−1 at sections PN, TK, ASUKA, 137E, and OK, respectively. The transport of nutrients in these sections suggests the presence of the Kuroshio nutrient stream from its upstream to downstream regions. The deep current structure of the Ryukyu Current (section OK) contributes to the same order of nitrate transport as does the Kuroshio from the East China Sea (section TK) to the area south of Japan; however, the former only has one-fifth the volume transport of the latter. A budget calculation suggests that the downstream increase of transported nitrate along the Kuroshio is mainly caused by the recirculation of nitrate into the Kuroshio. This conclusion, however, depends on water depth. In the upper layers (< 26.5σθ), the downstream change of nitrate concentration along the Kuroshio and that from the recirculation of nitrate has a significant contribution to the downstream increase of nitrate transport along the Kuroshio. In the deep layers (> 26.5σθ), the change in nitrate concentration is small and the Kuroshio recirculation dominates the downstream increase of nitrate transport.

The Kuroshio East of Taiwan and in the East China Sea and the currents East of Ryukyu Islands during early summer of 1996

1998 ◽  
Vol 54 (3) ◽  
pp. 217-226 ◽  
Author(s):  
Yaochu Yuan ◽  
Arata Kaneko ◽  
Jilan Su ◽  
Xiaohua Zhu ◽  
Yonggang Liu ◽  
...  
Keyword(s):  
East China Sea ◽  
Early Summer ◽  
East China ◽  
Ryukyu Islands ◽  
The East China Sea ◽  
China Sea ◽  
The Kuroshio

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.

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