Dynamics of cross-shelf water exchanges off Pearl River Estuary in summer

Liu，Zhiqiang1,2,4; Zu，Tingting3,4; Gan，Jianping2

2020-11-01

10.1016/j.pocean.2020.102465

PROGRESS IN OCEANOGRAPHY   影响因子和分区

0079-6611

Dynamics regulating the cross-isobath momentum and water exchanges over the shelf in the vicinity of the Pearl River Estuary (PRE) in July 2015 and 2017 are examined using comprehensive observations and multiple-level nested high-resolution numerical simulations. Although driven by the upwelling- and downwelling-favorable winds in July 2015 and 2017, respectively, the shelf currents and the cross-isobath exchanges illustrate great similarity during these two periods. This study finds that the southwesterly-induced flow downstream in the Taiwan Strait maintained the northeastward upwelling currents in the vicinity of the PRE that caused the extensive upslope invasion of the deep shelf waters. The cross-shelf exchanges of the shelf and coastal waters mainly occur over the irregular topography off the entrance of the HuangMaoHai estuary, to the west of the Dangan Island, and over a shallow trough to the east of Hong Kong. It is also rationalized that the intensified exchange flow is established by an along-shelf pressure gradient force that notably exceeds the contributions from the bottom and surface Ekman transport as well as the nonlinearity of the shelf current in the water column. The baroclinicity of the shelf and coastal waters plays minimal roles in altering this along-shore pressure gradient force, especially when upwelling-favorable winds prevail. The exchange flows in the water column thereby show great similarity with those in the bottom layer, where the bottom along-shore pressure gradient force is jointly imposed by the nonlinear advection of relative vorticity and frictional stress curl in both the surface and bottom layers. The spatial variation of these terms is regulated by the intensity of the shelf current and along-shelf variation of bottom topography.

Cross-isobath Transport Depth-integrated Potential Vorticity Dynamics Exchange flow Northern South China Sea Shelf circulation

SCI ; EI

英语

第一 ; 通讯

Theme-based Research Scheme (OCEAN_HK project) of the Hong Kong Research Grants Council[T21-602/16-R] ; National (China) Key Basic Research Development Program[2015CB954004] ; National Natural Science Foundation of China[41906016,41576003] ; Science, Technology and Innovation Commission of Shenzhen Municipality[JCYJ20190809144411368]

Oceanography

Oceanography

WOS:000596202300002

PERGAMON-ELSEVIER SCIENCE LTD

20204509466669

Vorticity ; Pressure gradient ; Topography

Waterways:407.2 ; Fluid Flow, General:631.1 ; Pressure Measurements:944.4 ; Materials Science:951

GEOSCIENCES

2-s2.0-85095407151

Scopus

1.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shen Zhen,China
2.Department of Ocean Science & Department of Mathematics,Hong Kong University of Science and Technology,Hong Kong,Hong Kong
3.State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou,China
4.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou),Guangzhou,China

Liu，Zhiqiang,Zu，Tingting,Gan，Jianping. Dynamics of cross-shelf water exchanges off Pearl River Estuary in summer[J]. PROGRESS IN OCEANOGRAPHY,2020,189.

Liu，Zhiqiang,Zu，Tingting,&Gan，Jianping.(2020).Dynamics of cross-shelf water exchanges off Pearl River Estuary in summer.PROGRESS IN OCEANOGRAPHY,189.

Liu，Zhiqiang,et al."Dynamics of cross-shelf water exchanges off Pearl River Estuary in summer".PROGRESS IN OCEANOGRAPHY 189(2020).