Abyssal Boundary Current along the Northwestern Perimeter of the Philippine Basin

Chaen, Masaaki; Fukasawa, Masao; Maeda, Akio; Sakurai, Masahito; Masaki, Takeshi

doi:10.1016/s0422-9894(08)71317-5

Cited by 14 publications

(15 citation statements)

References 5 publications

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“…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: 99%

“…It should be noted that the bathymetric data around the mooring site were interpolated from the General Bathymetric Chart of the Oceans (GEBCO) compiled by Smith and Sandwell (1997), which may contain inaccuracies in this region and would need to be updated with more bathymetric observations in the future. The current data were different from the abyssal current observed at 400 m above the sea bottom southeast of Okinawa and Taiwan Island (Chaen et al, 1993). The latter was fl owing equatorward parallel to the local bottom contour.…”

Section: Field Observationcontrasting

confidence: 64%

“…The observed low-frequency abyssal current direction was not parallel to the local bottom contour, different from the current southeast of Okinawa and Taiwan Island (Chaen et al, 1993). Though this may be due to errors in the bathymetry data of GEBCO (Smith and Sandwell, 1997), it may also indicate that the abyssal circulation pattern around this region is complex.…”

Section: Discussionmentioning

confidence: 72%

“…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: 99%

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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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Section: Discussioncontrasting

confidence: 99%

Section: Field Observationcontrasting

confidence: 64%

Section: Discussionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

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Observation of the abyssal western boundary current in the Philippine Sea

Zhai

Wang

et al. 2014

Chin. J. Ocean. Limnol.

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“…Figure 4 shows the mean absolute velocity field for times when all referencing current meters were working and IES8 was deployed. Along the lower part of the continental slope this mean is missing a persistent deep westward flow [ Fukasawa et al , 1986; Chaen et al , 1993]. The deep current meters (>3000 dbar) moored at CM6 (see Figure 1) recorded this westward flow.…”

Section: Methodsmentioning

confidence: 99%

Kuroshio temporal and spatial variations south of Japan determined from inverted echo sounder measurements

et al. 2002

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[1] The Affiliated Surveys of the Kuroshio off Ashizuri-Misaki (ASUKA) project is a collaboration between scientists in Japan and the United States to improve our understanding of the structure and dynamics of the Kuroshio off the coast of southwest Japan. In this project an array of nine inverted echo sounders and nine current meter moorings were deployed for 2 years (1993)(1994)(1995) along a line extending 1000 km from Shikoku. Numerous hydrographic profiles along this section were used to determine the regional gravest empirical modes (GEMs), which relate vertical profiles of temperature and specific volume anomaly to vertical acoustic echo time. These GEMs were used in conjunction with the inverted echo sounder data to calculate 2-year time series of entire sections of relative geostrophic velocity and temperature. Current meter data provided absolute velocity references for the geostrophic velocity sections. In addition, a time series of Kuroshio position was determined from the GEM temperature sections. It shows three big (>80 km displacement) and three little offshore meanders of the Kuroshio occurring in February, May/June, and October of both years. This suggests a 4-month periodicity, possibly phase-locked to the annual cycle. The meanders may be caused by mesoscale eddies arriving from the east. The observed meanders were preceded by low Kuroshio volume transport and were followed by high Kuroshio volume transport. The Kuroshio volume and temperature transports were highly variable, with respective means of 65 ± 4 Sv and 3.7 ± 0.2 PW and standard deviations of 20 Sv and 0.9 PW.INDEX TERMS: 4576

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The delineation of dyanmical characteristics of circulations and their changes in the surface, subsurface, mid-depth and deep layers of the westernmost part of the North Pacific

Teramoto

1996

J Oceanogr

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Abyssal Boundary Current along the Northwestern Perimeter of the Philippine Basin

Cited by 14 publications

References 5 publications

Observation of the abyssal western boundary current in the Philippine Sea

Observation of the abyssal western boundary current in the Philippine Sea

Kuroshio temporal and spatial variations south of Japan determined from inverted echo sounder measurements

The delineation of dyanmical characteristics of circulations and their changes in the surface, subsurface, mid-depth and deep layers of the westernmost part of the North Pacific

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