Tidal Straining, Density Currents, and Stirring in the Control of Estuarine Stratification

Simpson, John H.; Brown, Justin; Matthews, Janice R.; Allen, G.

doi:10.2307/1351581

Cited by 799 publications

(677 citation statements)

References 12 publications

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“…The surface layer mixing may break through the stratification layer and bring the surface nutrients up to the surface layer caused by wind stirring [1,28]. The wind stirring-caused mixing is proportional to the wind power input, given by [29].…”

Section: Methodsmentioning

confidence: 99%

Quantification of Typhoon-Induced Phytoplankton Blooms Using Satellite Multi-Sensor Data

et al. 2018

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Using satellite-based multi-sensor observations, this study investigates Chl-a blooms induced by typhoons in the Northwest Pacific (NWP) and the South China Sea (SCS), and quantifies the blooms via wind-induced mixing and Ekman pumping parameters, as well as pre-typhoon mixed-layer depth (MLD). In the NWP, the Chl-a bloom is more correlated with the Ekman pumping than with the other two parameters, with an R 2 value of 0.56. In the SCS, the wind-induced mixing and Ekman pumping have comparable correlations with the Chl-a increase, showing R 2 values of 0.4~0.6. However, the MLD exhibits a negative correlation with the Chl-a increase. A multi-parameter quantification model of the Chl-a bloom strength achieves better results than the single-parameter regressions, yielding a more significant R 2 value of 0.80, and a lower regression rms of 0.18 mg·m −3 in the SCS, and the R 2 value in the NWP is also improved compared with the single-parameter regressions. The multi-parameter quantification model of Chl-a blooms is more accurate in the SCS than in the NWP, due to the fact that nutrient profiles in the NWP are uniform from surface to a deep depth (300 m). Thus, the Chl-a blooms are more correlated with the upper ocean dynamical processes in the SCS where a shallower nutricline is found.

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Section: Methodsmentioning

confidence: 99%

Quantification of Typhoon-Induced Phytoplankton Blooms Using Satellite Multi-Sensor Data

et al. 2018

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“…As a result, the Rhine ROFI switches between a well-mixed and a stratified state at multiple timescales. The competition between stratifying and destratifying processes determines the state of the ROFI in time and space (Simpson 1997;Simpson et al 1990;Souza and Simpson 1997;. The processes causing stratification and mixing can be classified into reversible and irreversible processes (see Table 1).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous measurements of tidal straining and advection at two parallel transects far downstream in the Rhine ROFI

Rijnsburger

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Tongeren³

et al. 2016

Ocean Dynamics

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This study identifies and unravels the processes that lead to stratification and destratification in the far field of a Region of Freshwater Influence (ROFI). We present measurements that are novel for two reasons: (1) measurements were carried out with two vessels that sailed simultaneously over two cross-shore transects; (2) the measurements were carried out in the far field of the Rhine ROFI, 80 km downstream from the river mouth. This unique four dimensional dataset allows the application of the 3D potential energy anomaly equation for one of the first times on field data. With this equation, the relative importance of the depth mean advection, straining and nonlinear processes over one tidal cycle is assessed. The data shows that the Rhine ROFI extends 80 km downstream and periodic stratification is observed. The analysis not only shows the Van Oord, Rotterdam, The Netherlands important role of cross-shore tidal straining but also the significance of along-shore straining and depth mean advection. In addition, the nonlinear terms seem to be small. The presence of all the terms influences the timing of maximum stratification. The analysis also shows that the importance of each term varies in the cross-shore direction. One of the most interesting findings is that the data are not inline with several hypotheses on the functioning of straining and advection in ROFIs. This highlights the dynamic behaviour of the Rhine ROFI, which is valuable for understanding the distribution of fine sediments, contaminants and the protection of coasts.

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“…1). The large tidal range (in excess of 10 m on spring tides) generates fast tidal currents (> 1 m/s) that interact with the freshwater inflow complicating the dynamics of the region (Simpson et al, 1990). Stratification is promoted through surface heating and buoyancy input from river discharge and rainfall, while mixing is induced by tidal and wind stirring (Simpson and Bowers, 1981).…”

Section: Introductionmentioning

confidence: 99%

“…Tidal flow asymmetry, due to the shoaling depths causing the flood flow to be on average a factor of 1.2 faster than the ebb flow, leads to asymmetric tidal mixing addition to the typical strain induced periodic stratification (SIPS) (Simpson et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

Impact of operational model nesting approaches and inherent errors for coastal simulations

et al. 2016

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A region of freshwater influence (ROFI) under hypertidal conditions is used to demonstrate inherent problems for nested operational modelling systems. Such problems can impact the accurate simulation of freshwater export within shelf seas, so must be considered in coastal ocean modelling studies. In Liverpool Bay (our UK study site), freshwater inflow from 3 large estuaries forms a coastal front that moves in response to tides and winds. The cyclic occurrence of stratification and remixing is important for the biogeochemical cycles, as nutrient and pollutant loaded freshwater is introduced into the coastal system. Validation methods, using coastal observations from fixed moorings and cruise transects, are used to assess the simulation of the ROFI, through improved spatial structure and temporal variability of the front, as guidance for best practise model setup. A structured modelling system using a 180 m grid nested within a 1.8 km grid demonstrates how compensation for error at the coarser resolution can have an adverse impact on the nested, high resolution application. Using 2008, a year of typical calm and stormy periods with variable river influence, the sensitivities of the ROFI dynamics to initial and boundary conditions are investigated. It is shown that accurate representation of the initial water column structure is important at the regional scale and that the boundary conditions are most important at the coastal scale. Although increased grid resolution captures the frontal structure, the accuracy in frontal position is determined by the offshore boundary conditions and therefore the accuracy of the coarser regional model.

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Tidal Straining, Density Currents, and Stirring in the Control of Estuarine Stratification

Cited by 799 publications

References 12 publications

Quantification of Typhoon-Induced Phytoplankton Blooms Using Satellite Multi-Sensor Data

Quantification of Typhoon-Induced Phytoplankton Blooms Using Satellite Multi-Sensor Data

Simultaneous measurements of tidal straining and advection at two parallel transects far downstream in the Rhine ROFI

Impact of operational model nesting approaches and inherent errors for coastal simulations

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