TY - JOUR
T1 - Wind- and density-driven circulation in a bay on the Sanriku ria coast, Japan
T2 - study of Shizugawa Bay facing the Pacific Ocean
AU - Takahashi, Daisuke
AU - Endo, Hikaru
AU - Minegishi, Yuki
AU - Gomi, Yasushi
AU - Kaneko, Kenji
N1 - Funding Information:
Acknowledgements We extend our gratitude to Mrs. H. Endo and T. Sato of the Japan Fisheries Cooperative and Mr. M. Shoji of Miyagi Prefectural Government for their help and cooperation. This work was supported in part by the project “Tohoku Ecosystem-Associated Marine Sciences” through a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology. Part of the present study was conducted at Tohoku University and in Hokkaido National Fisheries Research Institute, Japan Fisheries Research and Education Agency, but the content of this study does not necessarily reflect their views. Thanks are extended to the editor and anonymous reviewers for their valuable comments.
Publisher Copyright:
© 2017, The Oceanographic Society of Japan and Springer Japan KK.
PY - 2018/2/1
Y1 - 2018/2/1
N2 - Flow fields in Shizugawa Bay on the Sanriku ria coast, which faces the Pacific Ocean, were investigated using hydrographic observations for the purpose of understanding oceanographic conditions and the process of water exchanges in the bay after the 2011 earthquake off the Pacific coast of Tohoku. In spring to summer, density-driven surface outflow is part of estuarine circulation and is induced by a pressure gradient force under larger longitudinal gradients in density along with lower salinity water in the innermost part of the bay, regardless of wind forcing. In winter to summer, another density-driven current with a thermal structure is induced by a pressure gradient force under the smaller longitudinal density gradients in calm wind conditions. Particularly in winter, Tsugaru Warm Current water can be transported in the surface layer inside the bay. Wind-driven bay-scale circulation with downwind and upwind currents in the surface and deeper layers, respectively, is induced by strong longitudinal wind forcing under the smaller longitudinal density gradients, irrespective of season. Particularly in fall to spring, this circulation can cause the intrusions of oceanic water associated with Oyashio water and Tsugaru Warm Current water in the deeper layer. These results suggest that wind- and density-driven currents can produce the active exchange of water from inside and outside the bay throughout the year.
AB - Flow fields in Shizugawa Bay on the Sanriku ria coast, which faces the Pacific Ocean, were investigated using hydrographic observations for the purpose of understanding oceanographic conditions and the process of water exchanges in the bay after the 2011 earthquake off the Pacific coast of Tohoku. In spring to summer, density-driven surface outflow is part of estuarine circulation and is induced by a pressure gradient force under larger longitudinal gradients in density along with lower salinity water in the innermost part of the bay, regardless of wind forcing. In winter to summer, another density-driven current with a thermal structure is induced by a pressure gradient force under the smaller longitudinal density gradients in calm wind conditions. Particularly in winter, Tsugaru Warm Current water can be transported in the surface layer inside the bay. Wind-driven bay-scale circulation with downwind and upwind currents in the surface and deeper layers, respectively, is induced by strong longitudinal wind forcing under the smaller longitudinal density gradients, irrespective of season. Particularly in fall to spring, this circulation can cause the intrusions of oceanic water associated with Oyashio water and Tsugaru Warm Current water in the deeper layer. These results suggest that wind- and density-driven currents can produce the active exchange of water from inside and outside the bay throughout the year.
KW - Density-driven current
KW - Estuarine circulation
KW - Hydrographic observation
KW - Intrusion of oceanic water
KW - Sanriku ria coast
KW - Shizugawa Bay
KW - Wind-driven circulation
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U2 - 10.1007/s10872-017-0442-0
DO - 10.1007/s10872-017-0442-0
M3 - Article
AN - SCOPUS:85029074551
VL - 74
SP - 81
EP - 100
JO - Journal of Oceanography
JF - Journal of Oceanography
SN - 0916-8370
IS - 1
ER -