07 Sep 2023
 | 07 Sep 2023
Status: this preprint is open for discussion.

Influence of Stratification and Wind Forcing on the Dynamics of Lagrangian Residual Velocity in a Periodically Stratified Estuary

Fangjing Deng, Feiyu Jia, Rui Shi, Shuwen Zhang, Qiang Lian, Xiaolong Zong, and Zhaoyun Chen

Abstract. Wind and stratification play pivotal roles in shaping the structure of the Lagrangian residual velocity (LRV). However, the intricate dynamics by which wind and stratification modify the LRV remain poorly studied. This study derives numerical solutions of LRV components and eddy viscosity subcomponents to elucidate the dynamics within the periodically stratified Pearl River estuary. The vertical shear cross-estuary LRV (uL) is principally governed by the interplay among the eddy viscosity component (uLtu), the barotropic component (uLba), and the baroclinic component (uLgr) under stratified conditions. During neap tides, southwesterly winds notably impact uL by escalating uLtu by an order of magnitude within the upper layer. This transforms the eastward flow dominated by uLtu under wind influence into a westward flow dominated by uLba in upper shoal regions without wind forcing. The along-estuary LRV exhibits a gravitational circulation characterized by upper-layer outflow engendered by barotropic component (vLba) and lower-layer inflow predominantly driven by baroclinic component (vLgr). The presence of southwesterly winds suppresses along-estuary gravitational circulation by diminishing the magnitude of vLba and vLgr. The contributions of vLba and vLgr are approximately equal, while the ratio between uLba and uLgr (uLtu) fluctuates within the range of 1 to 2 in stratified waters. Under unstratified conditions, LRV exhibits a lateral shear structure due to differing dominant components compared to stratified conditions. In stratified scenarios, the eddy viscosity component of LRV is predominantly governed by the turbulent mean component, while it succumbs to the influence of the tidal straining component in unstratified waters.

Fangjing Deng et al.

Status: open (until 09 Nov 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Fangjing Deng et al.

Fangjing Deng et al.


Total article views: 102 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
74 22 6 102 3 3
  • HTML: 74
  • PDF: 22
  • XML: 6
  • Total: 102
  • BibTeX: 3
  • EndNote: 3
Views and downloads (calculated since 07 Sep 2023)
Cumulative views and downloads (calculated since 07 Sep 2023)

Viewed (geographical distribution)

Total article views: 101 (including HTML, PDF, and XML) Thereof 101 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 03 Oct 2023
Short summary
Southwesterly winds impact cross-estuary flows by amplifying the eddy viscosity component during smaller tides. Moreover, they modify along-estuary gravitational circulation by diminishing both the barotropic and baroclinic components. Stratification results in contrasting sheared flows, distinguished by different dominant components compared to destratified conditions. Additionally, the eddy viscosity component is governed by various subcomponents in diverse stratified waters.