Submission No.:01246

Coastal dispersal of the land-derived tracer in an estuary and a continental shelf margin
UCHIYAMA, Yusuke1∗ ; SUZUE, Yota1
1

Kobe University

Coastal marginal seas and estuaries are generally dumpsites for waster water from sewage and power plants (e.g., Uchiyama etal., 2014). Accidental leakage of toxic materials may result in serious hazardous incidents that should be predicted and assessed
urgently upon the occurrence. We therefore develop an offline passive tracer model that computes 3D dispersal of arbitrary Eulerian tracers with a point source capability by exploiting 3D oceanic model reanalysis and prediction such as JCOPE2 (Miyazawa
et al., 2009). The purposes of the present study are to investigate (1) reproducibility of the offline tracer dispersal against theonline result, and (2) difference in spatiotemporal variability of the leaked tracers in a semi-enclosed estuary (viz., Seto InlandSea, Japan; SIS) and in an open coast environment on the continental margin off Shizuoka Prefecture on the Pacific side of Japan.
For the first objective, we analyze with the double-nested JCOPE2-ROMS downscaling system for the entire SIS at the horizontal resolution of 600 m. The release site is chosen on the southern coast of the Iyo Sea. The tracer has been discharged for
11 days in 4 different seasons since the 1st day in Feb., May, Aug., and Nov., 2013, and tracked for 31 days after each release.
Overall similarity in the dispersal pattern is obtained for both the online and offline cases, whereas some undesirable negative
concentration arisen from a discrete advection scheme induces a slight deviation in the inventory of the released tracer between
the two cases. Tidal oscillations enhance local dilution, while the month-long transport is dominated rather by inter-seasonalvariability of the clockwise circulation of the SIS. The comparative offline tracer computation for the open coast off Shizuoka
is conducted with another double-nested JCOPE2-ROMS downscaling model result for the Kuroshio region at the horizontal
resolution of 1 km. The tracer release occurs near the Cape Omaezaki and is done in the same way as the SIS runs. The Kuroshio
readily traps the released tracer in the offline open coast run, leading to immediate transport in the northeast direction. The
seasonal difference of the tracer dispersal is apparent, depending on the locations of the Kuroshio axis.
Keywords: coastal dispersal, Eulerian passive tracer, offline tracer model, ROMS, downscaling ocean model, JCOPE2

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投稿番号：01246

陸域起源トレーサーの沿岸域における分散解析：内湾および開放性海岸に対する比較実験
Coastal dispersal of the land-derived tracer in an estuary and a continental shelf margin
内山 雄介 1∗ ; 鈴江 洋太 1
UCHIYAMA, Yusuke1∗ ; SUZUE, Yota1
1
1

神戸大学大学院
Kobe University

Coastal marginal seas and estuaries are generally dumpsites for waster water from sewage and power plants (e.g., Uchiyama etal., 2014). Accidental leakage of toxic materials may result in serious hazardous incidents that should be predicted and assessed
urgently upon the occurrence. We therefore develop an offline passive tracer model that computes 3D dispersal of arbitrary Eulerian tracers with a point source capability by exploiting 3D oceanic model reanalysis and prediction such as JCOPE2 (Miyazawa
et al., 2009). The purposes of the present study are to investigate (1) reproducibility of the offline tracer dispersal against theonline result, and (2) difference in spatiotemporal variability of the leaked tracers in a semi-enclosed estuary (viz., Seto InlandSea, Japan; SIS) and in an open coast environment on the continental margin off Shizuoka Prefecture on the Pacific side of Japan.
For the first objective, we analyze with the double-nested JCOPE2-ROMS downscaling system for the entire SIS at the horizontal resolution of 600 m. The release site is chosen on the southern coast of the Iyo Sea. The tracer has been discharged for
11 days in 4 different seasons since the 1st day in Feb., May, Aug., and Nov., 2013, and tracked for 31 days after each release.
Overall similarity in the dispersal pattern is obtained for both the online and offline cases, whereas some undesirable negative
concentration arisen from a discrete advection scheme induces a slight deviation in the inventory of the released tracer between
the two cases. Tidal oscillations enhance local dilution, while the month-long transport is dominated rather by inter-seasonalvariability of the clockwise circulation of the SIS. The comparative offline tracer computation for the open coast off Shizuoka
is conducted with another double-nested JCOPE2-ROMS downscaling model result for the Kuroshio region at the horizontal
resolution of 1 km. The tracer release occurs near the Cape Omaezaki and is done in the same way as the SIS runs. The Kuroshio
readily traps the released tracer in the offline open coast run, leading to immediate transport in the northeast direction. The
seasonal difference of the tracer dispersal is apparent, depending on the locations of the Kuroshio axis.
キーワード: 沿岸域における分散, オイラー型パッシブトレーサー, オフライントレーサーモデル, ROMS, ダウンスケール
海洋モデル, JCOPE2
Keywords: coastal dispersal, Eulerian passive tracer, offline tracer model, ROMS, downscaling ocean model, JCOPE2

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