Vertical current structure and throughflow transport of the Kuroshio in the East China Sea, and south and east of JapanLecturer: Chia-Ping ChiangDate : 2009/03/05

Outlines

IntroductionLiterature ReviewsModel Description and ValidationConclusionFuture Work

Introduction ~ The Kuroshio

(H. Nitani 1972)(Kyushu)Tokara(straight)(meandering)(Honshu)(Boso Peninsula) (deep Pacific Ocean)(the Kuroshio Extension)M. Andres et al. (2008)S. Itoh et al. (2008)

Literature Reviews

M. Kawabe (1995): 19631975(non-large meander path)19751991(larger meander path)NLM pathLM path

T. Kagimoto et al. (1997): (ocean general circulation modelOGCM) PN-line25 Sv

H. Ichikawa et al. (2000): 19811992 WaterKuroshio Thermocline Water, Kuroshio Surface Water, Kuroshio Intermediate Water, and ECS Shelf Water contribute to volume trapsport, 28.5 Sv

Literature Reviews

H. Ichikawa et al. (2002):

M. Kashima et al. (2003): 19931995(Shikoku)700m1500m3000m(700m1500m)(1500m3000m)

X. Guo et al. (2003) (triply nested OGCM) (East China Sea)(30N129E)

Literature Reviews

E. Oka et al. (2003): (CTDP)(ADCP)(current velocity)(potential vorticity)

H. Yoshinari et al. (2004): OGCM(MOM2.2, Modular Ocean Model Ver. 2.2)(ETOPO5, Earth Topography -5 Minute)19602000(1)NCEP/NCAR (2)NECMWF

M. Kawabe (2005): 1990(LM path)TakaraLM

Literature Reviews

Deep Current east of Japan

S. Fujio et al. (2000): 19871996-(Izu-Ogasawara Trench)(34N)199534N30N30N34N58 Sv30N5 Sv34N22 Sv

S. Fujio et al. (2005): (Japanese Trench)(38N)200013.5 Sv5.5 Sv38N

Model DescriptionA 4th order, high resolution, and fully way-coupled duo-grid Pacific Ocean Model (DUPOM).The control volume equations include the conservation of the fluxes of momentum (momentum balance), heat (energy balance), salt (material balance) across control volume faces.

The TAI DomainGrid resolution: 1/81/8Longitude: 100~150ELatitude: 0~50N

Special Diagnositcs:PN-Line (East China Sea, ECS)TK-Line (Tokara Strait)ASUKA-Line (South of Japan)34N (Izu-Ogasawara Trench)38N (Japan Trench)

Circulation pattern in the vicinity of ECSQiu and Imasato (1990). The annual mean pattern of surface current derived from GEK data between 1953 and 1984.Lie et al. (1998). The annual mean pattern of surface current derived from trajectories of surface drifters between 1989 and 1996.

Circulation pattern in the vicinity of ECSThe present model. The snapshot of the pattern of surface current in Year 35 Day 61.

Model ValidationPN-Line (ECS) : 0 ~ 1000 m depth, (126.2E, 30.0N) ~ (128.2E, 27.5N).

TK-Line (Tokara Strait) :0 ~ 1000 m depth, (130.0E, 28.6N) ~ (130.5E, 30.3N).ASUKA-Line (South of Japan) : 0 ~ 1500 m depth, (133.0E, 32.8N) ~ (136.5E, 26.0N).

34N (Izu-Ogasawara Trench) : Over 2000 m depth, (140.0E, 34.0N) ~ (144.0E, 34.0N).

38N (Japan Trench) : Over 2000 m depth, (142.0E, 38.0N) ~ (148.0E, 38.0N).

Vertical current structure normal to PN lineE. Oka and M. Kawabe (1998). Distribution of geostrophic velocity based on the quarterly data of CTD at the PN line during 1988-1994. (a) winter, (b) spring (c) summer, and (d) fall.

Vertical current structure normal to PN lineYamashio et al. (1990). Vertical sections of seasonal mean geostrophic current normal to section PN referred to hydrographic and GEK velocity during 1972-1986.The present model. Vertical sections of seasonal mean geostrophic current normal to section PN During Year 27-29.Vmax: autumn 103 cm/secVmin: spring 72 cm/secVcounter about 6 ~9 cm/sec

Vertical current structure normal to PN lineOka et al. (2003). Distribution of average geostrophic velocity (cm/sec) at the PN line during 198997.The present model. Vertical sections of seasonal mean geostrophic current normal to section PN in Year 27, 28, and 29.Vmean, max: 98 cm/secVcounter: 7 cm/sec

Time series of volume transport (VT) across the PN line (1 Sv[]106 m3/sec)Saiki, 1982; Hinata, 1996. Time series of the Kuroshio transport across PN line.T. Kagimoto et al. (1997). Seasonal transport variations across the PN line. The solid line denotes the geostrophic transport relative to 700 db from Nagasaki Marine Observatory.

Time series of volume transport (VT) across the PN line (1 Sv[]106 m3/sec)The present model. Time series of VT across the PN line during Year 27-29. The black dashed line: yearly mean of VT ~ 29 Sv Upper Layer: < 100 m depthIntermediate Layer: 100 ~ 700 m depthDeep Layer: > 700 m depthLong-term mean during 28 years from 1973 to 2000 is 25.8 Sv. (Nagasaki Marine Observatory, Japan Meteorological Agency)The mean VT is 25.4 Sv based on the hydrographic data from 1973 to 1993. (Hinata 1996)

Vertical current structure normal to TK lineOka et al. (2003). Distribution of average geostrophic velocity (cm/sec) at the TK line during 198797.The present model. Vertical sections of seasonal mean geostrophic current normal to section TK in Year 27, 28, and 29.Vmean, max: 53 cm/secVcounter: 6 cm/sec

Vertical current structure normal to TK lineThe present model. Vertical sections of seasonal mean geostrophic current normal to section TK During Year 27-29.Vmax: summer 63 cm/secVmin: winter 51 cm/secVcounter : 4~8 cm/sec

Time series of VT across the TK lineThe present model. Time series of VT across the TK line during Year 27-29. The black dashed line: yearly mean of VT ~ 24 Sv Upper Layer: < 100 m depthIntermediate Layer: 100 ~ 700 m depthDeep Layer: > 700 m depthZhu et al. (2006) conducted an inverse calculation based on 101 CTD and 13 XBT/XCTD casts by R/V Chofu-Maru and R/V Shumpu-Maru of the Japan Meteorological Agency from October to December 2000. The total NVTs at section TK is 26.48 Sv.

Vertical current structure normal to ASUKA line(Upper panel) S. Imawaki (1995). Geostrophic calculation referred to 2000 m in the deep area and at the bottom in the shallow area.(Lower panel) T. Kagimoto et al. (1997). model.The present model. Vertical sections of seasonal mean geostrophic current normal to section ASUKA in Year 27, 28, and 29.Vmean, max: 66 cm/secVcounter: -27 cm/sec

Time series of VT across the ASUKA lineImawaki et al. (2001) calculated upper 1000 m transport derived from absolute geostrophic velocity which includes the information of the TOPEX/POSEIDON altimeter data and in-situ observations.T. Kagimoto et al. (1997). The dashed line shows the total transport variations across the ASUKA line.

Time series of VT across the ASUKA lineThe present model. Time series of VT across the ASUKA line during Year 27-29. The black dashed line: yearly mean of VT ~ 2 Sv Upper Layer: < 100 m depthIntermediate Layer: 100 ~ 1500 m depthDeep Layer: > 1500 m depthZhu et al. (2006) conducted an inverse calculation based on 101 CTD and 13 XBT/XCTD casts by R/V Chofu-Maru and R/V Shumpu-Maru of the Japan Meteorological Agency from October to December 2000. The total NVTs at section ASUKA is 63.7 Sv.

Eastward and northward velocity at 34N (trench floor )S. Fujio et al. (2000)C1: 3400.5N, 14150.7E, 4900 m depth; the eastward and northward velocities are -0.2 cm/sec and -1.9 cm/sec, respectively. F1: 3359.6N, 14150.5E, 5110 m depth; the eastward and northward velocities are -0.6 cm/sec and -2.5 cm/sec , respectively.The present model.3-year temporal mean of u and v are -0.09 cm/sec and -5.844 cm/sec, respectively.

Eastward and northward velocity at 34N (eastern flank )S. Fujio et al. (2000)O1: 3356.9N, 14231.5E, 3900 m depth; the eastward and northward velocities are -2.0 cm/sec and 7.3 cm/sec, respectively.The present model. Time series of VT across the ASUKA line during Year 27-29. 3-year temporal mean of u and v are 2.94 cm/sec and -14.8469 cm/sec, respectively.

Time series of VT across 34NThe present model. Time series of VT across 34N line during Year 27-29. The black dashed line: yearly mean of VT ~ -308 Sv Upper Layer: < 100 m depthIntermediate Layer: 100 ~ 2000 m depthDeep Layer: > 2000 m depthS. Fujio et al. (2000) The southward transport above the western flank was estimated to be 5-8 Sv. The northward transport above the eastern flank 5-22 Sv.

Vertical current structure normal to 38NThe present model. Vertical sections of seasonal mean geostrophic current normal to section 38N in Year 27, 28, and 29.S. Fujio (2005). Geostrophic velocity referred to 2000 db at 38N. Vmean, max: 30 cm/secVcounter: -45 cm/sec

Time series of VT across 38NThe present model. Time series of VT across 38 N line during Year 27-29. The black dashed line: yearly mean of VT ~ 106 Sv Upper Layer: < 100 m depthIntermediate Layer: 100 ~ 2000 m depthDeep Layer: > 2000 m depthS. Fujio et al. (2005) used direct current measurements and hydrographic observations to investigate deep currents east of Japan,. Below 2000 m, the deep transports above the trench were southward 5.5 Sv and northward 13.5 Sv.

ConclusionFair or Good Results:Vertical current structure: Sections PN, TK, ASUKA, and 38N.Zonal and meridional Velocity: Sections 34N.Time series of VT: Sections PN and TK.

Bad Results:Time series of VT: Sections ASUKA , 34N and 38N.

Program:Add output for 34N.The position of 38N should be slightly modified.

Future WorkGet ready my extended abstract as soon as possible.

Thanks For Your Listening !