The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data
The large variations in salinity at the salinity maximum in the northern South China Sea (NSCS), as an indicator for the changes in the Kuroshio intrusion (KI), play an important role in the hydrological cycle. The high salinity here is more than 34.65 at the salinity maximum and is intriguing. In t...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-02-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/9/2/227 |
| _version_ | 1827588729338855424 |
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| author | Hui Shen Li Li Jianlong Li Zhiguo He Yuezhang Xia |
| author_facet | Hui Shen Li Li Jianlong Li Zhiguo He Yuezhang Xia |
| author_sort | Hui Shen |
| collection | DOAJ |
| description | The large variations in salinity at the salinity maximum in the northern South China Sea (NSCS), as an indicator for the changes in the Kuroshio intrusion (KI), play an important role in the hydrological cycle. The high salinity here is more than 34.65 at the salinity maximum and is intriguing. In the past, the salinity was difficult to trace in the entire NSCS over long periods due to a lack of high-quality observations. However, due to the availability of accumulated temperature and salinity (T-S) profiles from the Argo program, it is now possible to capture subsurface-maximum data on a large spatiotemporal scale. In this study, the salinity maximum distributed in the subsurface of 80 to 200 m at a density of 23.0–25.5 <i>σ<sub>θ</sub></i> was extracted from decades of Argo data (on the different pressure surfaces, 2006–2019). We then further studied the spatial distribution and seasonal variation of the salinity maximum and its anomalously high salinity. The results suggest that a high salinity (salinity > 34.65, most of which is located at the shallow depths < 100 m) at the subsurface salinity-maximum layer often occurs in the NSCS, especially near the Luzon Strait, which accounts for about 23% of the total salinity maximum. In winter, the anomalously high salinity at the shallow subsurface salinity maximum can extend to the south of 17° N, while it rarely reaches 18° N and tends to locate at deeper waters in summer. The T-S values of the anomalously high-salinity water are between the mean T-S values in the NSCS and north Pacific subsurface water, implying that the outer sea water gradually mixes with the South China Sea water after passing through the Luzon Strait. Finally, our results show that the factors play an important role in the appearance and distribution of the anomalously high salinity at the subsurface salinity maximum, including the strength of the Kuroshio intrusion, the local wind stress curl and the anticyclonic eddy shedding from the loop current. |
| first_indexed | 2024-03-09T00:41:38Z |
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| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-09T00:41:38Z |
| publishDate | 2021-02-01 |
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| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-61399108fae44a3bbb01a4366352401c2023-12-11T17:47:31ZengMDPI AGJournal of Marine Science and Engineering2077-13122021-02-019222710.3390/jmse9020227The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo DataHui Shen0Li Li1Jianlong Li2Zhiguo He3Yuezhang Xia4Institute of Port and Offshore Engineering, Ocean College, Zhejiang University, Zhoushan 316021, ChinaInstitute of Port and Offshore Engineering, Ocean College, Zhejiang University, Zhoushan 316021, ChinaCollege of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, ChinaInstitute of Port and Offshore Engineering, Ocean College, Zhejiang University, Zhoushan 316021, ChinaInstitute of Port and Offshore Engineering, Ocean College, Zhejiang University, Zhoushan 316021, ChinaThe large variations in salinity at the salinity maximum in the northern South China Sea (NSCS), as an indicator for the changes in the Kuroshio intrusion (KI), play an important role in the hydrological cycle. The high salinity here is more than 34.65 at the salinity maximum and is intriguing. In the past, the salinity was difficult to trace in the entire NSCS over long periods due to a lack of high-quality observations. However, due to the availability of accumulated temperature and salinity (T-S) profiles from the Argo program, it is now possible to capture subsurface-maximum data on a large spatiotemporal scale. In this study, the salinity maximum distributed in the subsurface of 80 to 200 m at a density of 23.0–25.5 <i>σ<sub>θ</sub></i> was extracted from decades of Argo data (on the different pressure surfaces, 2006–2019). We then further studied the spatial distribution and seasonal variation of the salinity maximum and its anomalously high salinity. The results suggest that a high salinity (salinity > 34.65, most of which is located at the shallow depths < 100 m) at the subsurface salinity-maximum layer often occurs in the NSCS, especially near the Luzon Strait, which accounts for about 23% of the total salinity maximum. In winter, the anomalously high salinity at the shallow subsurface salinity maximum can extend to the south of 17° N, while it rarely reaches 18° N and tends to locate at deeper waters in summer. The T-S values of the anomalously high-salinity water are between the mean T-S values in the NSCS and north Pacific subsurface water, implying that the outer sea water gradually mixes with the South China Sea water after passing through the Luzon Strait. Finally, our results show that the factors play an important role in the appearance and distribution of the anomalously high salinity at the subsurface salinity maximum, including the strength of the Kuroshio intrusion, the local wind stress curl and the anticyclonic eddy shedding from the loop current.https://www.mdpi.com/2077-1312/9/2/227salinity maximumanomalously high salinityKuroshio intrusionnorthern South China SeaArgo |
| spellingShingle | Hui Shen Li Li Jianlong Li Zhiguo He Yuezhang Xia The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data Journal of Marine Science and Engineering salinity maximum anomalously high salinity Kuroshio intrusion northern South China Sea Argo |
| title | The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data |
| title_full | The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data |
| title_fullStr | The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data |
| title_full_unstemmed | The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data |
| title_short | The Seasonal Variation of the Anomalously High Salinity at Subsurface Salinity Maximum in Northern South China Sea from Argo Data |
| title_sort | seasonal variation of the anomalously high salinity at subsurface salinity maximum in northern south china sea from argo data |
| topic | salinity maximum anomalously high salinity Kuroshio intrusion northern South China Sea Argo |
| url | https://www.mdpi.com/2077-1312/9/2/227 |
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