Quantifying dispersion in an estuary: A Lagrangian drifter approach

Spencer, David M.; Lemckert, Charles James; Yu, Yingying; Gustafson, Johann; Lee, Joe; Zhang, Hong

doi:10.2112/si70-006.1

Cited by 13 publications

(11 citation statements)

References 17 publications

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“…The dynamical relation between the Lagrangian particle population forming the convex hull and the bulk ensemble of tracer particles enclosed by it represents another aspect of this diagnostic that could be exploited in investigations of turbulent structure formation. In recent years, convex hull calculations have been used to study diverse topics such as the size of spreading GPS-enabled drifters moving on the surfaces of lakes and rivers [21,22], star-forming clusters [23], forest fires [24], proteins [25,26], or clusters of contaminant particles [27]. Studies of the relationships between random walks, anomalous diffusion, extreme statistics and convex hulls have been motivated by animal home ranges [28][29][30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Extreme-value statistics from Lagrangian convex hull analysis for homogeneous turbulent Boussinesq convection and MHD convection

et al. 2017

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We investigate the utility of the convex hull of many Lagrangian tracers to analyze transport properties of turbulent flows with different anisotropy. In direct numerical simulations of statistically homogeneous and stationary Navier-Stokes turbulence, neutral fluid Boussinesq convection, and MHD Boussinesq convection a comparison with Lagrangian pair dispersion shows that convex hull statistics capture the asymptotic dispersive behavior of a large group of passive tracer particles. Moreover, convex hull analysis provides additional information on the sub-ensemble of tracers that on average disperse most efficiently in the form of extreme value statistics and flow anisotropy via the geometric properties of the convex hulls. We use the convex hull surface geometry to examine the anisotropy that occurs in turbulent convection. Applying extreme value theory, we show that the maximal square extensions of convex hull vertices are well described by a classic extreme value distribution, the Gumbel distribution. During turbulent convection, intermittent convective plumes grow and accelerate the dispersion of Lagrangian tracers. Convex hull analysis yields information that supplements standard Lagrangian analysis of coherent turbulent structures and their influence on the global statistics of the flow.

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Section: Introductionmentioning

confidence: 99%

Extreme-value statistics from Lagrangian convex hull analysis for homogeneous turbulent Boussinesq convection and MHD convection

et al. 2017

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“…4) to inform the circulation by measuring surface current and were used as indicator for calibrating the model. The design of the drifters was inspired by the small drifter from Spencer et al (2014) using AMOD AGL3080 GPS Data Loggers stored in a PVC container bolted to the top of the frame (Fig. 4).…”

Section: Measurements Of Physical Parameters (Waves Currents and Salinity)mentioning

confidence: 99%

Water circulation and impact on water quality in the southwest of Efate Island, Vanuatu

Faivre

Sami

Mackey

et al. 2021

Marine Pollution Bulletin

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In Small Island Developing States (SIDS), water pollution is not monitored or assessed frequently enough to fully understand the processes, impacts of water quality issues and what solutions are available This study investigated flushing time in Erakor lagoon and Port Vila Bay, Vanuatu using a numerical model developed in Delft3D. Microbial contamination by Escherichia coli was detected in multiple locations in the lagoon system with counts exceeding thresholds related to human health concerns. Modelling demonstrated a poor flushing time overall with a further decrease as the influence of waves and wind increased, especially in Vila Bay. Sea level rise resulted in an increase in flushing time downstream of the lagoon near the open sea, while with a decrease upstream and in Vila Bay. Based on these results, we recommend long-term continuous monitoring and identification of higher risks areas to prioritise decisions around wastewater management.

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“…Flow path measurements are being conducted by using manned vessels to track water moving at an average surfaceflow velocity and to measure concentration changes (Table 1; Hitchcock et al 2004, Dagg et al 2005, Gruberts et al 2012, Gruberts and Paidere 2014. Floating instrument platforms also are being used to mount sensors and enable deployment to capture flow path variability in process rates in lakes (Stocker and Imberger 2003), rivers (Spencer et al 2014), Table 2. Comparison of the information gained and limitations of fixed-site, snapshot, and flow path measurement approaches.…”

Section: Flow Path Approach (Lagrangian Reference Frame)mentioning

confidence: 99%

New strategies for measuring rates of environmental processes in rivers, lakes, and estuaries

Ensign¹,

Doyle²,

Gardner³

2017

Freshwater Science

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A central goal in limnology is measurement of physical, biogeochemical, and biological process rates. We can measure process rates from the temporal and spatial patterns they create in a measured variable, and we use 3 approaches for making those measurements: the fixed-site approach for detecting temporal pattern at a location, the snapshot approach for detecting spatial pattern at an instant in time, and the flow path approach for detecting temporal pattern as it changes through space. To compare and contrast these approaches, we present patterns in temperature collected simultaneously based on all 3 approaches. Translating these patterns into process rates requires different assumptions for each approach, and these assumptions lead to uncertainty in process rates. We propose that these assumptions and related uncertainty can be reduced by making simultaneous measurements based on all 3 approaches. Each approach fills gaps in the spatial and temporal patterns measured by the others, and these patterns can be combined to derive a process rate. We develop a conceptual theory to support this strategy for measuring process rate based on 2 criteria: the mixing time of a water body and the analytical limitations of the measurement. This new strategy for measuring process rates in aquatic environments has the potential to increase the resolution of rate measurements, reduce their uncertainty, and enhance limnologists' ability to resolve process rates from an increasing flow of environmental data.

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Quantifying dispersion in an estuary: A Lagrangian drifter approach

Cited by 13 publications

References 17 publications

Extreme-value statistics from Lagrangian convex hull analysis for homogeneous turbulent Boussinesq convection and MHD convection

Extreme-value statistics from Lagrangian convex hull analysis for homogeneous turbulent Boussinesq convection and MHD convection

Water circulation and impact on water quality in the southwest of Efate Island, Vanuatu

New strategies for measuring rates of environmental processes in rivers, lakes, and estuaries

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