Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017
The Kuroshio takes a greatly southward displaced path called a large-meander (LM) path off the southern coast of Japan on interannual to decadal time scales. The transition of the current path from a non-large-meander path to an LM path is the most salient ocean current variation south of Japan. The...
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Frontiers Media S.A.
2021-01-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2020.583481/full |
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| author | Akira Nagano Yusuke Yamashita Keisuke Ariyoshi Takuya Hasegawa Takuya Hasegawa Hiroyuki Matsumoto Masanao Shinohara |
| author_facet | Akira Nagano Yusuke Yamashita Keisuke Ariyoshi Takuya Hasegawa Takuya Hasegawa Hiroyuki Matsumoto Masanao Shinohara |
| author_sort | Akira Nagano |
| collection | DOAJ |
| description | The Kuroshio takes a greatly southward displaced path called a large-meander (LM) path off the southern coast of Japan on interannual to decadal time scales. The transition of the current path from a non-large-meander path to an LM path is the most salient ocean current variation south of Japan. The change in pressure on the seafloor due to the formation of the LM path in September 2017 is of critical importance to understand the dynamics of the LM path and to distinguish the change due to the Kuroshio path variation from changes due to crustal deformation. Hence, we examined the seafloor pressure across the continental slope off the eastern coast of Kyushu for the period March 2014 to April 2019. The pressure and its cross-slope gradient over the continental slope shallower than 3,000 m beneath near the Kuroshio are invariable. As a mesoscale current path disturbance, called a small meander, passed over the observation stations, the pressure decreased by approximately 0.1 dbar on the continental slope deeper than 3000 m and was kept low until the end of the observation period (April 2019). The pressure decrease is consistent with the changes in sea surface height and subsurface water density and is caused by the baroclinic enhancement of the Shikoku Basin local recirculation. This seafloor pressure change implies a strengthening of the deep southwestward current, possibly as a part of a deep cyclonic circulation in the Shikoku Basin. The present study demonstrated that, in addition to altimetric sea surface height data, hydrographic data are useful to distinguish the ocean variation in seafloor pressure from the variation due to crustal deformation, and vice versa. |
| first_indexed | 2024-12-24T04:56:22Z |
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| id | doaj.art-69d1fed311004a9696a667b1661e03d0 |
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| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-24T04:56:22Z |
| publishDate | 2021-01-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-69d1fed311004a9696a667b1661e03d02022-12-21T17:14:23ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632021-01-01810.3389/feart.2020.583481583481Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017Akira Nagano0Yusuke Yamashita1Keisuke Ariyoshi2Takuya Hasegawa3Takuya Hasegawa4Hiroyuki Matsumoto5Masanao Shinohara6Global Ocean Observation Research Center, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, JapanDisaster Prevention Research Institute, Kyoto University, Kyoto, JapanResearch and Development Center for Earthquake and Tsunami Forecasting, JAMSTEC, Yokohama, JapanFaculty of Environmental Earth Science, Hokkaido University, Sapporo, JapanGraduate School of Science, Tohoku University, Sendai, JapanResearch and Development Center for Earthquake and Tsunami Forecasting, JAMSTEC, Yokohama, JapanEarthquake Research Institute, The University of Tokyo, Tokyo, JapanThe Kuroshio takes a greatly southward displaced path called a large-meander (LM) path off the southern coast of Japan on interannual to decadal time scales. The transition of the current path from a non-large-meander path to an LM path is the most salient ocean current variation south of Japan. The change in pressure on the seafloor due to the formation of the LM path in September 2017 is of critical importance to understand the dynamics of the LM path and to distinguish the change due to the Kuroshio path variation from changes due to crustal deformation. Hence, we examined the seafloor pressure across the continental slope off the eastern coast of Kyushu for the period March 2014 to April 2019. The pressure and its cross-slope gradient over the continental slope shallower than 3,000 m beneath near the Kuroshio are invariable. As a mesoscale current path disturbance, called a small meander, passed over the observation stations, the pressure decreased by approximately 0.1 dbar on the continental slope deeper than 3000 m and was kept low until the end of the observation period (April 2019). The pressure decrease is consistent with the changes in sea surface height and subsurface water density and is caused by the baroclinic enhancement of the Shikoku Basin local recirculation. This seafloor pressure change implies a strengthening of the deep southwestward current, possibly as a part of a deep cyclonic circulation in the Shikoku Basin. The present study demonstrated that, in addition to altimetric sea surface height data, hydrographic data are useful to distinguish the ocean variation in seafloor pressure from the variation due to crustal deformation, and vice versa.https://www.frontiersin.org/articles/10.3389/feart.2020.583481/fullKuroshiorecirculationsea surface heightocean bottom pressurelarge meanderShikoku basin |
| spellingShingle | Akira Nagano Yusuke Yamashita Keisuke Ariyoshi Takuya Hasegawa Takuya Hasegawa Hiroyuki Matsumoto Masanao Shinohara Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017 Frontiers in Earth Science Kuroshio recirculation sea surface height ocean bottom pressure large meander Shikoku basin |
| title | Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017 |
| title_full | Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017 |
| title_fullStr | Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017 |
| title_full_unstemmed | Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017 |
| title_short | Seafloor Pressure Change Excited at the Northwest Corner of the Shikoku Basin by the Formation of the Kuroshio Large-Meander in September 2017 |
| title_sort | seafloor pressure change excited at the northwest corner of the shikoku basin by the formation of the kuroshio large meander in september 2017 |
| topic | Kuroshio recirculation sea surface height ocean bottom pressure large meander Shikoku basin |
| url | https://www.frontiersin.org/articles/10.3389/feart.2020.583481/full |
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