Effect of tropical cyclones on residual circulation and momentum balance in a subtropical estuary and inlet: Observation and simulation

Abstract

[1] A three-dimensional (3-D) hydrodynamic model, Curvilinear-Grid Hydrodynamics in 3-D (CH3D), and observation data are used to investigate the effects of Tropical Storms Fay and Hanna in 2008 on the spatial structure of residual circulation and momentum balance inside the subtropical estuarine system of the Northern Coastal Basin and St. Augustine Inlet. During a typical tidal cycle, four residual eddies are formed: two strong eddies inside of the inlet and two weaker eddies outside of the inlet. During Tropical Storms Fay and Hanna the alongshore component of the northeasterly winds disrupted the ocean-side eddies first and forced the alongshore southeasterly current. Owing to not-so-strong local winds, residual flow at the mouth of the inlet never became complete inflow. However, following Tropical Storm Fay's landfall, flow inside the inlet became complete outflow owing to relaxing wind and the remote wind effect created by the alongshore component of the southeasterly wind. The residual circulation returned to its prestorm condition in 4 days owing to relatively short storm duration. Model results revealed that the cross-sectional residual flow pattern observed at the inlet mouth is highly variable with time and location of the cross section. Comparison of various terms in the horizontal momentum equations shows that the balance is primarily between the barotropic pressure gradient and nonlinear advection. Although the wind stress and bottom friction briefly become significant in the balance, they are still at least an order of magnitude smaller. Baroclinic pressure gradient is weak despite the increase in precipitation and river discharge.Citation: Tutak, B., and Y. P. Sheng (2011), Effect of tropical cyclones on residual circulation and momentum balance in a subtropical estuary and inlet: Observation and simulation,

Wave-driven along-channel subtidal flows in a well-mixed ocean inlet

“…Accelerations of the inlet flows between the offshore and inlet sites (Figure ) could affect the subtidal momentum balance via the advective acceleration terms [ Hench et al ., ; Cáceres et al ., ; Hench and Luettich , ; Li and O'Donnell , ; Winant , ; Waterhouse and Valle‐Levinson , ; Tutak and Sheng , ]. However, consistent with prior modeling studies in well‐mixed, shallow, tidal estuaries, rough estimates suggest the two horizontal advection terms in the channel partially cancel (see Appendix ), and their sum (black dashed curve, Figures and ) appears to be small ( O (10 −5 to 10 −4 ) m 2 /s 2 ) compared with the dominant ( O (10 −3 ) m 2 /s 2 ) momentum balance terms [ Jay , ; Olabarrieta et al ., ].…”

“…Subtidal fluctuations also can have a significant effect on the fluxes through inlets and on the momentum balances [Swenson and Chuang, 1983]. For example, strong winds can cause pressure gradients that change the direction or strength of the inlet flows [Smith, 1993;Geyer, 1997;Wong and Moses-Hall, 1998;Chant, 2001;Wong and Valle-Levinson, 2002;C aceres et al, 2003;Waterhouse and Valle-Levinson, 2010;Tutak and Sheng, 2011;Li, 2013]. Numerical simulations also suggest that wave forcing may be important along ocean coasts [Piedracoba et al, 2005;Bertin et al, 2009;Malhadas et al, 2009;Olabarrieta et al, 2011;Dodet et al, 2013].…”

Simulating complex storm surge dynamics: Three‐dimensionality, vegetation effect, and onshore sediment transport

“…Storm surge dynamics are dominated by the interaction of surface winds and bottom friction, though other factors such as wave [ Sheng and Liu , ], Coriolis [ Kennedy et al ., 2011], and baroclinic effects [ Tutak and Sheng , ] can be quite important. Recent efforts to simulate Hurricane Ike have been effective at simulating accurate water levels in 2‐D using large, high‐resolution computational domains [ Kerr et al ., , ; Hope et al ., ].…”

Simulating Storm Surge and Inundation Along the Taiwan Coast During Typhoons Fanapi in 2010 and Soulik in 2013

“…2) which is an integrated storm surge modeling system (Sheng et al 2006(Sheng et al , 2008(Sheng et al , 2010aTutak and Sheng 2011) built upon the CH3D (Curvilinear-grid Hydrodynamics in 3D) circulation model (Sheng 1987(Sheng , 1990). The CH3D model solves the continuity equation and the horizontal momentum equations in nonorthogonal boundary-fitted horizontal coordinates and a sigma coordinate system in the vertical dimension, making it suitable for complex coastal zone applications.…”