Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension
A graphical clustering approach was used to objectively identify prevalent surface circulation patterns in the East/Japan Sea (EJS). By applying a spectral clustering algorithm, three distinct patterns in the East Korea Warm Current (EKWC) and its extension were identified from daily maps of reanaly...
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2024-12-01
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| author | Eun Young Lee Dong Eun Lee Hye-Ji Kim Haedo Baek Young Ho Kim Young-Gyu Park |
| author_facet | Eun Young Lee Dong Eun Lee Hye-Ji Kim Haedo Baek Young Ho Kim Young-Gyu Park |
| author_sort | Eun Young Lee |
| collection | DOAJ |
| description | A graphical clustering approach was used to objectively identify prevalent surface circulation patterns in the East/Japan Sea (EJS). By applying a spectral clustering algorithm, three distinct patterns in the East Korea Warm Current (EKWC) and its extension were identified from daily maps of reanalyzed sea surface heights spanning the past 30 years. The results are consistent with previous studies that used manual classification of the EKWC’s Lagrangian trajectories, highlighting the effectiveness of spectral clustering in accurately characterizing the surface circulation states in the EJS. Notably, the recent dominance of northern paths, as opposed to routes along Japan’s coastline or those departing from Korea’s east coast further south, has prompted focused re-clustering of the northern paths according to their waviness. This re-clustering, with additional emphasis on path length, distinctly categorized two patterns: straight paths (SPs) and large meanders (LMs). Notably, SPs have become more prevalent in the most recent years, while LMs have diminished. An autoregression analysis reveals that seasonal anomalies in the cluster frequency in spring tend to persist through to the following autumn. The frequency anomalies in the SPs correlate strongly with the development of pronounced anomalies in the gradient of meridional sea surface height and negative anomalies in the surface wind stress curl in the preceding cold seasons. This relationship explains the observed correlation between a negative Arctic Oscillation during the preceding winter and the increased frequency of SPs in the subsequent spring. The rapid increase in the occurrence of SPs indicates that a reduction in LMs limits the mixing of cold, fresh, northern waters with warm, saline, southern waters, thereby reinforcing the presence of SPs due to a strengthened gradient of meridional surface height and contributing to a slowdown in the regional overturning circulation. |
| format | Article |
| id | doaj-art-13da9aa028674a409faa590f8bb3a593 |
| institution | Kabale University |
| issn | 2077-1312 |
| language | English |
| publishDate | 2024-12-01 |
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| series | Journal of Marine Science and Engineering |
| spelling | doaj-art-13da9aa028674a409faa590f8bb3a5932024-12-27T14:33:38ZengMDPI AGJournal of Marine Science and Engineering2077-13122024-12-011212233810.3390/jmse12122338Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its ExtensionEun Young Lee0Dong Eun Lee1Hye-Ji Kim2Haedo Baek3Young Ho Kim4Young-Gyu Park5Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of KoreaResearch Institute of Marine Science, Department of Marine Environmental Science, Chungnam National University, Daejeon 34134, Republic of KoreaResearch Institute of Marine Science, Department of Marine Environmental Science, Chungnam National University, Daejeon 34134, Republic of KoreaDepartment of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of KoreaDivision of Earth Environmental System Science, Pukyong National University, Busan 48531, Republic of KoreaKorea Institute of Ocean Science and Technology, Busan 49111, Republic of KoreaA graphical clustering approach was used to objectively identify prevalent surface circulation patterns in the East/Japan Sea (EJS). By applying a spectral clustering algorithm, three distinct patterns in the East Korea Warm Current (EKWC) and its extension were identified from daily maps of reanalyzed sea surface heights spanning the past 30 years. The results are consistent with previous studies that used manual classification of the EKWC’s Lagrangian trajectories, highlighting the effectiveness of spectral clustering in accurately characterizing the surface circulation states in the EJS. Notably, the recent dominance of northern paths, as opposed to routes along Japan’s coastline or those departing from Korea’s east coast further south, has prompted focused re-clustering of the northern paths according to their waviness. This re-clustering, with additional emphasis on path length, distinctly categorized two patterns: straight paths (SPs) and large meanders (LMs). Notably, SPs have become more prevalent in the most recent years, while LMs have diminished. An autoregression analysis reveals that seasonal anomalies in the cluster frequency in spring tend to persist through to the following autumn. The frequency anomalies in the SPs correlate strongly with the development of pronounced anomalies in the gradient of meridional sea surface height and negative anomalies in the surface wind stress curl in the preceding cold seasons. This relationship explains the observed correlation between a negative Arctic Oscillation during the preceding winter and the increased frequency of SPs in the subsequent spring. The rapid increase in the occurrence of SPs indicates that a reduction in LMs limits the mixing of cold, fresh, northern waters with warm, saline, southern waters, thereby reinforcing the presence of SPs due to a strengthened gradient of meridional surface height and contributing to a slowdown in the regional overturning circulation.https://www.mdpi.com/2077-1312/12/12/2338the East/Japan Seameridional overturningthe East Korea Warm Currentspectral clustering |
| spellingShingle | Eun Young Lee Dong Eun Lee Hye-Ji Kim Haedo Baek Young Ho Kim Young-Gyu Park Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension Journal of Marine Science and Engineering the East/Japan Sea meridional overturning the East Korea Warm Current spectral clustering |
| title | Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension |
| title_full | Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension |
| title_fullStr | Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension |
| title_full_unstemmed | Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension |
| title_short | Use of Spectral Clustering for Identifying Circulation Patterns of the East Korea Warm Current and Its Extension |
| title_sort | use of spectral clustering for identifying circulation patterns of the east korea warm current and its extension |
| topic | the East/Japan Sea meridional overturning the East Korea Warm Current spectral clustering |
| url | https://www.mdpi.com/2077-1312/12/12/2338 |
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