Three-Dimensional Water Exchanges in the Shelf Circulation System of the Northern South China Sea Under Climatic Modulation From ENSO

Cui, Lingbo1; Liu, Zhiqiang2,3; Chen, Ying1; Cai, Zhongya1,4

2024-04-01

10.1029/2023JC020290

JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS   影响因子和分区

2169-9275

2169-9291

["Using the numerical calculations of exposure time ((theta) over bar), this study investigated the three-dimensional characteristics of water exchanges associated with the coastal-shelf circulations of the Northern South China Sea (NSCS). The circulation connectivity and its interannual variability under the modulation of El Nino Southern Oscillation (ENSO) were investigated. The (theta) over bar gradually increased from approximately 50 days over the outer shelf to more than 150 days in the shallower coastal seas with the Beibu Gulf displaying a significantly longer (theta) over bar (approximately 300 days). The Beibu Gulf played an influential role in the water exchange that had a contribution of over 30% to (theta) over bar in the most regions. The results from sensitivity experiments indicate that the wind forcing is the primary controller of (theta) over bar and the boundary flux plays a secondary role. Specifically, the wind enhances water exchange in western NSCS, particularly in the Beibu Gulf and Yuexi region. Conversely, boundary fluxes facilitate exchanges in the eastern shelf, such as Yuedong region. Analysis revealed a clear modulation from ENSO on water exchange, wherein El Nino and La Nina years displayed symmetrical morphologies in (theta) over bar distribution anomalies, albeit with varying intensities. During El Nino years, the weakened southwestward shelf current increased (theta) over bar and the shelf water was less likely to reach the Beibu Gulf, and once arrived, these waters were trapped inside to elongate (theta) over bar. In contrast, during La Nina years, the strengthened southwestward shelf current shortened (theta) over bar and more shelf waters were transported away from the NSCS by an intensified southwestward shelf current.","Plain Language Summary Coastal water exchange, impacted by land, ocean, and atmospheric factors, tends to show complexity. This research explored the water movement in the Northern South China Sea (NSCS), focusing particularly on the water exchange rate, known as the exposure time, and examined its response to the climatic variability. We found the water exchange time decreased from land (exceeds 150 days) to the outer shelf (similar to 50 days) with the largest values in Beibu Gulf (similar to 300 days). The Beibu Gulf had significant influence on the water exchange that it contributed more than 30% to the water exchange time for most of the NSCS regions. The numerical experiments found that the water exchange is mainly affected by the wind forcing and boundary fluxes play a minor role. Additionally, the research illustrated the influence of El Nino and La Nina on water exchange. During El Nino years, the water movement pattern opposes the mean circulation direction, which results in a longer water exchange time. Conversely, during La Nina years, more water is transported out of the NSCS swiftly, which reduces the water exchange time. The findings from this study helped to reveal the cumulative impacts of shelf current in altering the net mass transport."]

water exchange coastal-shelf circulations transport pattern ENSO interannual variability

SCI

英语

其他

Science and Technology Development Fund, Macau, SAR["0093/2020/A2","SKL-IOTSC-2021-2023"] ; Science and Technology Development Fund, Macau SAR[EF007/IOTSC-CZY/2022/HKUST] ; Center for Ocean Research in Hong Kong and Macau["JCYJ20210324105401004","20220815093611001"] ; Science, Technology and Innovation Commission of Shenzhen Municipality[AoE/P-601/23-N]

Oceanography

Oceanography

WOS:001198178100001

AMER GEOPHYSICAL UNION

GEOSCIENCES

Web of Science

1.Univ Macau, Dept Ocean Sci & Technol, State Key Lab Internet Thing Smart City, Macau, Peoples R China
2.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen, Peoples R China
3.Southern Univ Sci & Technol, Ctr Complex Flows & Soft Matter Res, Shenzhen, Peoples R China
4.Ctr Ocean Res Hong Kong & Macau CORE, Hong Kong, Peoples R China

Cui, Lingbo,Liu, Zhiqiang,Chen, Ying,et al. Three-Dimensional Water Exchanges in the Shelf Circulation System of the Northern South China Sea Under Climatic Modulation From ENSO[J]. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,2024,129(4).

Cui, Lingbo,Liu, Zhiqiang,Chen, Ying,&Cai, Zhongya.(2024).Three-Dimensional Water Exchanges in the Shelf Circulation System of the Northern South China Sea Under Climatic Modulation From ENSO.JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS,129(4).

Cui, Lingbo,et al."Three-Dimensional Water Exchanges in the Shelf Circulation System of the Northern South China Sea Under Climatic Modulation From ENSO".JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS 129.4(2024).