A fifty-year eddy-resolving simulation of the world ocean has been performed on the Earth Simulat... more A fifty-year eddy-resolving simulation of the world ocean has been performed on the Earth Simulator for the first time. Several global aspects of the circulations and regional characteristics in some spe- cific areas simulated in the high-resolution model are compared to available observations. The results demon- strate a promising capability of representing realistically meso-scale variability, including separation of the western
Eos, Transactions American Geophysical Union, 2008
The Kuroshio Extension system links to North Pacific climate through its role in subtropical-subp... more The Kuroshio Extension system links to North Pacific climate through its role in subtropical-subpolar exchange, the formation and distribution of mode waters, and the intensification of the extratropical storm track across the North Pacific. The Kuroshio Extension System ...
Sensitivity study of the air–ice drag coefficient C Dai is presented with an ice–ocean coupled mo... more Sensitivity study of the air–ice drag coefficient C Dai is presented with an ice–ocean coupled model for the Sea of Okhotsk. The C Dai × 103 value is varied from 2 to 5 based on the direct measurements in the region. The maximum volume transport of the East Sakhalin Current and the mean sea ice velocity were intensified as C Dai increased. The sensitivity experiment with the ice–water drag coefficient C Diw showed that the East Sakhalin Current volume transport is hardly affected by C Diw but significantly intensified by C Dai. While the ice drift in the off-ice-edge direction was intensified by the increase in C Dai and the decrease in C Diw, the ice edge location was nearly unchanged. This was due to melting caused by the relatively warm water inflow from the North Pacific. That is, sea ice extent in the region is strongly influenced by melting caused by a large ice–ocean heat transfer. In the active melting regions, the ice–ocean heat transfer of more than 100 W/m2 occurred even in mid-winter. This is the same order as the cooling by air in winter, and a heat insulation capacity of sea ice is weakened in such regions.
Flow structure in the Australian–Antarctic basin is investigated using an eddy-resolving general ... more Flow structure in the Australian–Antarctic basin is investigated using an eddy-resolving general ocean circulation model and validated with iceberg and middepth float trajectories. A cyclonic circulation system between the Antarctic Circumpolar Current and Antarctic Slope Current consists of a large-scale gyre in the west (80–110° E) and a series of eddies in the east (120–150° E). The western gyre has an annual
The Journal of the Acoustical Society of America, 2001
ABSTRACT Travel times of reciprocal acoustic transmissions from a 5‐transceiver acoustic tomograp... more ABSTRACT Travel times of reciprocal acoustic transmissions from a 5‐transceiver acoustic tomography array over a 1000‐km‐scale domain in the Kuroshio Extension (KE) region during summer 1997 are used to investigate the barotropic tidal currents and range‐averaged large‐scale low‐frequency currents as well as their relative vorticity. Inverse techniques are employed to estimate the low‐frequency range‐and‐depth averaged (barotropic) currents every 3 or 6 h from the differential acoustic travel times. Eight major tidal constituent amplitudes and phases derived from the high‐frequency acoustic travel times agree well with those found from the TOPEX/POSEIDON tidal model TPXO.5 [Egbert et al., 1994]. The results show that the range‐averaged barotropic currents along the section in the KE recirculation gyre flowed westward in about 4 cm/s with an uncertainty of 0.8 mm/s; this is consistent with the result of the ADCP survey on WOCE P‐14N experiment, and comparable with the surface geostrophic current velocity 5 m/s determined from the SSHA of the TOPEX/POSEIDON altimeter, indicating that barotropic currents are dominant in the Kuroshio Extension recirculation gyre. Estimated daily averaged relative vorticity over a 155 000 km2 area in the KE recirculation region has a near‐zero mean (1.84×10−7 s−1).
... 1991) than in the main part of the subtropical gyre (26.8σ θ , Talley 1993). ... 4a). Low sal... more ... 1991) than in the main part of the subtropical gyre (26.8σ θ , Talley 1993). ... 4a). Low salinity water characteristic of NPIW is seen as a tongue extending southwestward in the NEC and southward in the Luzon Undercurrent (LUC; Qu et al. ...
Time-averaged structure of the Kuroshio/Oyashio system east of Japan was examined using historica... more Time-averaged structure of the Kuroshio/Oyashio system east of Japan was examined using historical hydro- graphic data. Unlike most of the earlier climatological analyses, the data were averaged along isopycnal rather than pressure surfaces in a 0.5 83 0.58 grid. As a result, most of the detailed phenomena associated with the narrow western boundary currents were revealed. Water from the Oyashio
... Based on a simplified version of the model proposed by Woods (1985; see also Williams 1991), ... more ... Based on a simplified version of the model proposed by Woods (1985; see also Williams 1991), Qiu and Huang (1995) estimated the subduction rate using the Levitus (1982) climatology and Hellerman and Rosenstein (1983) wind stress data. ...
The spatial and temporal characteristics of cyclonic eddies in the Antarctic Divergence off Adéli... more The spatial and temporal characteristics of cyclonic eddies in the Antarctic Divergence off Adélie Coast are described using repeated in situ observations between 2001 and 2003, satellite observations, and results of a high-resolution ocean general circulation model. Satellite ocean color images and altimetry clearly revealed a series of cyclonic eddies, with diameters of about 100-150 km that were separated by
A fifty-year eddy-resolving simulation of the world ocean has been performed on the Earth Simulat... more A fifty-year eddy-resolving simulation of the world ocean has been performed on the Earth Simulator for the first time. Several global aspects of the circulations and regional characteristics in some spe- cific areas simulated in the high-resolution model are compared to available observations. The results demon- strate a promising capability of representing realistically meso-scale variability, including separation of the western
Eos, Transactions American Geophysical Union, 2008
The Kuroshio Extension system links to North Pacific climate through its role in subtropical-subp... more The Kuroshio Extension system links to North Pacific climate through its role in subtropical-subpolar exchange, the formation and distribution of mode waters, and the intensification of the extratropical storm track across the North Pacific. The Kuroshio Extension System ...
Sensitivity study of the air–ice drag coefficient C Dai is presented with an ice–ocean coupled mo... more Sensitivity study of the air–ice drag coefficient C Dai is presented with an ice–ocean coupled model for the Sea of Okhotsk. The C Dai × 103 value is varied from 2 to 5 based on the direct measurements in the region. The maximum volume transport of the East Sakhalin Current and the mean sea ice velocity were intensified as C Dai increased. The sensitivity experiment with the ice–water drag coefficient C Diw showed that the East Sakhalin Current volume transport is hardly affected by C Diw but significantly intensified by C Dai. While the ice drift in the off-ice-edge direction was intensified by the increase in C Dai and the decrease in C Diw, the ice edge location was nearly unchanged. This was due to melting caused by the relatively warm water inflow from the North Pacific. That is, sea ice extent in the region is strongly influenced by melting caused by a large ice–ocean heat transfer. In the active melting regions, the ice–ocean heat transfer of more than 100 W/m2 occurred even in mid-winter. This is the same order as the cooling by air in winter, and a heat insulation capacity of sea ice is weakened in such regions.
Flow structure in the Australian–Antarctic basin is investigated using an eddy-resolving general ... more Flow structure in the Australian–Antarctic basin is investigated using an eddy-resolving general ocean circulation model and validated with iceberg and middepth float trajectories. A cyclonic circulation system between the Antarctic Circumpolar Current and Antarctic Slope Current consists of a large-scale gyre in the west (80–110° E) and a series of eddies in the east (120–150° E). The western gyre has an annual
The Journal of the Acoustical Society of America, 2001
ABSTRACT Travel times of reciprocal acoustic transmissions from a 5‐transceiver acoustic tomograp... more ABSTRACT Travel times of reciprocal acoustic transmissions from a 5‐transceiver acoustic tomography array over a 1000‐km‐scale domain in the Kuroshio Extension (KE) region during summer 1997 are used to investigate the barotropic tidal currents and range‐averaged large‐scale low‐frequency currents as well as their relative vorticity. Inverse techniques are employed to estimate the low‐frequency range‐and‐depth averaged (barotropic) currents every 3 or 6 h from the differential acoustic travel times. Eight major tidal constituent amplitudes and phases derived from the high‐frequency acoustic travel times agree well with those found from the TOPEX/POSEIDON tidal model TPXO.5 [Egbert et al., 1994]. The results show that the range‐averaged barotropic currents along the section in the KE recirculation gyre flowed westward in about 4 cm/s with an uncertainty of 0.8 mm/s; this is consistent with the result of the ADCP survey on WOCE P‐14N experiment, and comparable with the surface geostrophic current velocity 5 m/s determined from the SSHA of the TOPEX/POSEIDON altimeter, indicating that barotropic currents are dominant in the Kuroshio Extension recirculation gyre. Estimated daily averaged relative vorticity over a 155 000 km2 area in the KE recirculation region has a near‐zero mean (1.84×10−7 s−1).
... 1991) than in the main part of the subtropical gyre (26.8σ θ , Talley 1993). ... 4a). Low sal... more ... 1991) than in the main part of the subtropical gyre (26.8σ θ , Talley 1993). ... 4a). Low salinity water characteristic of NPIW is seen as a tongue extending southwestward in the NEC and southward in the Luzon Undercurrent (LUC; Qu et al. ...
Time-averaged structure of the Kuroshio/Oyashio system east of Japan was examined using historica... more Time-averaged structure of the Kuroshio/Oyashio system east of Japan was examined using historical hydro- graphic data. Unlike most of the earlier climatological analyses, the data were averaged along isopycnal rather than pressure surfaces in a 0.5 83 0.58 grid. As a result, most of the detailed phenomena associated with the narrow western boundary currents were revealed. Water from the Oyashio
... Based on a simplified version of the model proposed by Woods (1985; see also Williams 1991), ... more ... Based on a simplified version of the model proposed by Woods (1985; see also Williams 1991), Qiu and Huang (1995) estimated the subduction rate using the Levitus (1982) climatology and Hellerman and Rosenstein (1983) wind stress data. ...
The spatial and temporal characteristics of cyclonic eddies in the Antarctic Divergence off Adéli... more The spatial and temporal characteristics of cyclonic eddies in the Antarctic Divergence off Adélie Coast are described using repeated in situ observations between 2001 and 2003, satellite observations, and results of a high-resolution ocean general circulation model. Satellite ocean color images and altimetry clearly revealed a series of cyclonic eddies, with diameters of about 100-150 km that were separated by
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