Volume Transport Variability Southeast of Okinawa Island Estimated from Satellite Altimeter Data

Zhu, Xiao; Ichikawa, Hiroshi; Ichikawa, Kaoru; Takeuchi, Kensuke

doi:10.1007/s10872-005-0004-8

Cited by 41 publications

(38 citation statements)

References 12 publications

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“…3c). This is a well-known feature of the Ryukyu Current (Zhu et al, 2004), which is a branch current of the Kuroshio in the East China Sea (Andres et al, 2008). Although it is not very clear in Fig.…”

Section: Current Fields At the Five Sectionsmentioning

confidence: 88%

“…Imawaki et al (2001) ASUKA. Ichikawa et al (2004) also noted its influences on the Ryukyu Current and attributed the increase in volume transport from section OK (Zhu et al, 2004) to a section southeast of Amami island to the presence of the Kuroshio recirculation.…”

Section: Current Fields At the Five Sectionsmentioning

confidence: 98%

“…An approximate mass conservation was assumed within each of the eight layers, while an approximate salt conservation was assumed within the lower seven layers. By allowing small mass and salt unbalances in each layer, an optimum velocity was obtained at the reference level, which was set at a depth of 2000 m for sections OK, ASUKA, and 137E, 700 m for sections PN and TK, and at sea bottom if the water depth was shallower than a depth of 2000 m or 700 m. The optimum reference level for the inverse method to calculate the absolute geostrophic velocity was suggested to be 2000 dbar in the region southeast of the Ryukyu Islands (Yuan et al, 1998;Zhu et al, 2008) and in the Kuroshio region south of Japan (Kaneko et al, 2001), and to be 700 dbar at sections PN and TK (Guo et al, 2012;Wei et al, 2013). After obtaining the velocity at the reference level, the absolute geostrophic velocity normal to the line connecting the two stations at one-meter intervals in the vertical direction was obtained from the thermal winds relation.…”

Section: Y Guo Et Al: Spatial Variations In the Kuroshio Nutrienmentioning

confidence: 99%

“…In this paper, the nitrate flux and nitrate transport are calculated through four sections across the Kuroshio from its upstream region, the East China Sea (sections PN and TK), to its downstream region, the area south of Japan (sections ASUKA and 137E). In addition, we also examined section OK, which is east of the Ryukyu Islands where the Ryukyu Current is located (Zhu et al, 2004). While examining the nutrient flux and nutrient transport at five sections, our objectives are to confirm the presence of the Kuroshio nutrient stream from the East China Sea to the region south of Japan, reveal the downstream variations of the nutrient flux and nutrient transport along the path of the Kuroshio, and to clarify the factors controlling the spatial variations of the nutrients transported by the Kuroshio.…”

Section: Introductionmentioning

confidence: 99%

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

Guo

Zhu²,

Yu³

et al. 2013

Biogeosciences

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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

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Section: Current Fields At the Five Sectionsmentioning

confidence: 88%

Section: Current Fields At the Five Sectionsmentioning

confidence: 98%

Section: Y Guo Et Al: Spatial Variations In the Kuroshio Nutrienmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Guo

Zhu²,

Yu³

et al. 2013

Biogeosciences

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“…Andres et al (2008a) illustrated three events of the approaching anticyclonic (cyclonic) eddies that increased (decreased) the transports in the ECS through the Kerama Gap. Also, Zhu et al (2004) showed that the approaching anticyclonic/cyclonic eddies increased/decreased the volume transport southeast of Okinawa Island.…”

mentioning

confidence: 98%

The mesoscale eddies and Kuroshio transport in the western North Pacific east of Taiwan from 8-year (2003–2010) model reanalysis

Lee

Wang

et al. 2013

Ocean Dynamics

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The relationship between the Kuroshio volume transport east of Taiwan (~24°N) and the impinging mesoscale eddies is investigated using 8-year reanalysis of a primitive equation ocean model that assimilates satellite altimetry and SST data. The mean and fluctuations of the model Kuroshio transport agree well with the available observations. Analysis of model dynamic heights and velocity fields reveals three dominant eddy modes. The first mode describes a large eddy of~500 km in diameter, centered at 22°N. The second mode describes a pair of the north-south counter-rotating eddies of~400 km in diameter each, centered at 23°and 20°N, respectively. The third mode describes a pair of the east-west counter-rotating eddies of~300 km in diameter each, centered at 21°N. The associated velocity fields indicate eddies extending to 600-700 m in depth with vertical shears concentrated in the upper 400 m. All three modes and the model Kuroshio transport have similar dominant timescales of 70-150 days and generally are coherent. The decreased Kuroshio volume transports typically are associated with the impinging cyclonic eddies and the increased transports with the anticyclonic eddies. Selected drifter trajectories are presented to illustrate the three eddy modes and their correspondence with the varying Kuroshio transports.

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Observations of flow variability through the Kerama Gap between the East China Sea and the Northwestern Pacific

Wimbush

Park

et al. 2014

JGR Oceans

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The Kerama Gap, near the middle of the Ryukyu Island chain, is the deepest channel with a sill depth of 1050 m connecting the East China Sea (ECS) to the Northwestern Pacific. We measured the flow through the Kerama Gap from June 2009 to June 2011. The 2 year mean transport, 2.0 6 0.7 Sv, is into the ECS from the Northwestern Pacific; it contributes about 11% of the mean Kuroshio transport in the ECS at the PN line. Subtidal standard deviation of the transport through the Kerama Gap is 3.2 Sv, comparable to that of the PN-line Kuroshio transport (4.0 Sv), suggesting a significant effect of Kerama Gap transport on temporal variability of the Kuroshio transport in the ECS. Comparison with time series of satellite-measured sea surface height maps reveals that temporal variability of the Kerama Gap transport is related to the arrival of mesoscale eddies from the east: high (low) transport into the ECS is associated with the presence of a cyclonic (anticyclonic) eddy south of the Kerama Gap.

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Volume Transport Variability Southeast of Okinawa Island Estimated from Satellite Altimeter Data

Cited by 41 publications

References 12 publications

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

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

The mesoscale eddies and Kuroshio transport in the western North Pacific east of Taiwan from 8-year (2003–2010) model reanalysis

Observations of flow variability through the Kerama Gap between the East China Sea and the Northwestern Pacific

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