Abyssal current along the northern periphery of Shikoku Basin

Fukasawa, Masao; Teramoto, Toshihiko; Taira, Keisuke

doi:10.1007/bf02110196

Cited by 29 publications

(10 citation statements)

References 4 publications

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“…Fukasawa ef al. also reported ,that current direction is mainly westward on the bottom of landward slope in Nankai Trough off Cape Shiono, Kii Peninsula [7]. The results of ADCP measurements correspondent to these circulation feature.…”

Section: Results Of Muroro Observatorysupporting

confidence: 81%

Measurements of deep currents by ADCP attached on the real-time deep seafloor observatory

Mitsuzawa¹,

Iwase²,

Hirata³

et al. 2003

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492)

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Three systems of real-time deep seafloor observatory were deployed in the northwest Pacific around Japan. The first system was deployed in the Sagami Bay, 7km off Hatsushima Island, central Honshu in 1993. It was developed as a proto-type of the cable end station for the comprehensive seafloor monitoring network. The observatory was renewed in March 2000. The ADCP was installed in the observatory at a renewal. The second system was deployed at the landward slope of the Nankai Trough, 120 km off Cape Muroto, Shikoku, in March 1997. Third system was deployed at the landward slope of the southern Kurile Trench, 220 km off Kushiro, Hokkaido, in August 1999. The observation system consists of bottom seismometers, Tsunami pressure gauges and the cable end station which composed of several environmental monitoring instruments. ADCP (RDI BBADCP 150 kHz) is attached on the cable end station as the bottom current monitoring instrument. Measurement data of each observatory are transmitted to the land station in real-time using a submarine electro-optical cable. Bottom current profiles are measured as ranges of about 440 m in the Sagami Bay, about 150 m in the Nankai Trough, and about 360 m in the southern Kurile Trench using the ADCPs.Following phenomena were obtained as results and topics of the observation. 1) Deep exchange flow, which was divided in the internal boundary, was observed in the Sagami Bay.2) As the features of the deep currents, the southwestward current can be observed on the landward slope in the Nankai Trough.3) The strong bottom eddies were observed on the slope in the southern Kurile Trench.

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Section: Results Of Muroro Observatorysupporting

confidence: 81%

Measurements of deep currents by ADCP attached on the real-time deep seafloor observatory

Mitsuzawa¹,

Iwase²,

Hirata³

et al. 2003

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492)

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show abstract

“…This differed from the numerical model result below 5 000 m depth of Ishizaki (1994a), which showed an equatorward current. It also differed from the direct current observations southeast of Okinawa and Taiwan Island (Chaen et al, 1993) and along the northern periphery of Shikoku Basin (Fukasawa et al, 1987;Nagano et al, 2013). However, as the observed abyssal current showed signifi cant variations and fl owed southeastward before October 1, 2011, the discrepancy between the present observations and previous studies is possibly due to the different observation or model integration periods.…”

Section: Discussioncontrasting

confidence: 84%

“…In the Philippine Sea, the knowledge of the abyssal circulation was obtained mainly from numerical model simulations (Kubota and Ono, 1992;Ishizaki, 1994a, b) and synoptic hydrographic observations (Guan, 1990;Uehara and Taira, 1990;Kaneko et al, 1998;Kaneko et al, 2001). Several direct current observations were reported in the West Mariana Basin (Yoshioka et al, 1988), along the northern periphery of Shikoku Basin (Fukasawa et al, 1987;Nagano et al, 2013), and along the northwestern perimeter of the Philippine Basin (Chaen et al, 1993).…”

Section: Introductionmentioning

confidence: 94%

Observation of the abyssal western boundary current in the Philippine Sea

Zhai

Wang

et al. 2014

Chin. J. Ocean. Limnol.

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Mooring observations were conducted from July 16, 2011 to March 30, 2012 east of Mindanao, Philippines (127°2.8′E, 8°0.3′N) to observe the abyssal current at about 5 600 m deep and 500 m above the ocean bottom. Several features were revealed: 1) the observed abyssal current was highly variable with standard deviations of 57.3 mm/s and 34.0 mm/s, larger than the mean values of -31.9 and 16.6 mm/s for the zonal and meridional components, respectively; 2) low-frequency current longer than 6 days exhibited strong seasonal variation, fl owing southeastward (mean fl ow direction of 119.0° clockwise from north) before about October 1, 2011 and northwestward (mean fl ow direction of 60.5° counter-clockwise from north) thereafter; 3) the high-frequency fl ow bands were dominated by tidal currents O 1 , K 1 , M 2 , and S 2 , and near-inertial currents, whose frequencies were higher than the local inertial frequency. The two diurnal tidal constituents were much stronger than the two semidiurnal ones. This study provides for the fi rst time an observational insight into the abyssal western boundary current east of Mindanao based on long-term observations at one site. It is meaningful for further research into the deep and abyssal circulation over the whole Philippine Sea and the 3D structure of the western boundary current system in this region. More observational and high-resolution model studies are needed to examine the spatial structure and temporal variation of the abyssal current over a much larger space and longer period, their relation to the upper-layer circulation, and the underlying dynamics.

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“…Indirect inference from tracers such as silica (Tally and Joyce 1992) suggest northward deep flow along the western boundary. Current meter observations by Fukasawa et al (1986) in the Shikoku Basin south of Japan (west of the region considered by Talley and Joyce 1992) show deep mean currents of 5 to 10 cm s-toward the south-west (parallel to local isobaths). Northward flow of low silica water is contrary to that indicated by Figure 4, whereas the current meter observations are consistent with topographic stress.…”

Section: North Pacificmentioning

confidence: 92%

Statistical Methods in Physical Oceanography: Proceedings of 'Aha Huliko'a Hawaiian Winter Workshop Held in Manoa, Hawaii on January 12-15, 1993

Müller¹,

Henderson²

1993

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Abyssal current along the northern periphery of Shikoku Basin

Cited by 29 publications

References 4 publications

Measurements of deep currents by ADCP attached on the real-time deep seafloor observatory

Measurements of deep currents by ADCP attached on the real-time deep seafloor observatory

Observation of the abyssal western boundary current in the Philippine Sea

Statistical Methods in Physical Oceanography: Proceedings of 'Aha Huliko'a Hawaiian Winter Workshop Held in Manoa, Hawaii on January 12-15, 1993

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