scholarly journals Observation of the Dynamics and Horizontal Dispersion in a Shallow Intermittently Closed and Open Lake and Lagoon (ICOLL)

Water ◽  
2018 ◽  
Vol 10 (6) ◽  
pp. 776 ◽  
Author(s):  
Kabir Suara ◽  
Neda Mardani ◽  
Helen Fairweather ◽  
Adrian McCallum ◽  
Chris Allan ◽  
...  
Keyword(s):  
Horizontal Dispersion

Numerical Investigation of Wind Driven Circulation and Horizontal Dispersion in the Surface Layer of a Re-flooded Shallow Lake

2016 ◽  
Vol 3 (3) ◽  
pp. 693-710 ◽  
Author(s):  
Kyriakos Kopasakis ◽  
Chrysi Laspidou ◽  
Marios Spiliotopoulos ◽  
Dimitrios Kofinas ◽  
Nikolaos Mellios
Keyword(s):  
Surface Layer ◽  
Numerical Investigation ◽  
Shallow Lake ◽  
Horizontal Dispersion ◽  
Wind Driven Circulation

Horizontal dispersion within an anticyclonic mesoscale eddy

2001 ◽  
Vol 48 (4-5) ◽  
pp. 739-755 ◽  
Author(s):  
Adrian P Martin ◽  
Kelvin J Richards ◽  
Cliff S Law ◽  
Malcolm Liddicoat
Keyword(s):  
Mesoscale Eddy ◽  
Horizontal Dispersion

Impacts of meso and submesoscale dynamics on the horizontal dispersion of sinking particles from the surface to the deep ocean

2020 ◽  
Author(s):  
Lu Wang ◽  
Jonathan Gula ◽  
Jeremy Collin ◽  
Laurent Memery
Keyword(s):  
General Structure ◽  
Finite Size ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Horizontal Distribution ◽  
Particle Dispersion ◽  
Small Scale ◽  
Transport Pathways ◽  
Horizontal Dispersion ◽  
Sinking Particles

<p>Energetic eddy fields generated by meso and submesoscale dynamics induce tridimensional particle transport pathways, which complicate the interpretation of observed Particulate Organic Carbon (POC) fluxes using sediment traps. It is therefore of importance to understand how horizontal dispersion of particles is structured by these dynamics from surface to depth. In this modelling study, we use a Lagrangian method to backtrack sinking particles collected at various depths ranging from 500 m to 4700 m at the PAP (Porcupine Abyssal Plain) site. Particle trajectories are computed using high-resolution simulations of the Regional Ocean Modelling System (ROMS). Our results show that the horizontal distribution of particles with sinking velocities below 100 m d<sup>-1</sup> presents a large small-scale heterogeneity. Mesoscale eddies act to define the general structure of particle patches while submesoscale features shape particle distributions through convergence/divergence processes. Distribution patterns of particles tracked from different depths suggest regime shifts of particle dispersion between subsurface layers. To identify and quantify these regimes, we perform 2d experiments at specific depths from 100 m to 4000 m and relate the Lagrangian statistics to the characteristics of the different dynamical regimes identified using vertical profiles of eddy energy and Finite Size Lyapunov Exponents (FSLE) approach.                                                                                                                                                               </p>

Small- and medium-scale effects of high-flying aircraft exhausts on the atmospheric composition

1994 ◽  
Vol 12 (10/11) ◽  
pp. 979-985 ◽  
Author(s):  
I. L. Karol ◽  
Y. E. Ozolin
Keyword(s):  
Scale Effects ◽  
Aircraft Engine ◽  
Heterogeneous Reactions ◽  
Atmospheric Composition ◽  
Model Studies ◽  
Supersonic Aircraft ◽  
Horizontal Dispersion ◽  
Small Influence ◽  
Initial Evolution ◽  
Global Impacts

Abstract. Following numerous model studies of the global impacts of sub- and supersonic aircraft on the atmosphere, this paper assesses the separate aircraft engine exhaust effects of the 45°N cruise flight and at the 10- and 18-km levels of the July atmosphere. A box diffusion photochemical model in the cross-section plane of the flight trajectory is used to compute the effects of gas-phase and heterogeneous reactions on the condensation trail particles in the troposphere, and on the sulphate aerosols in the stratosphere. The enhanced horizontal dispersion of the exhaust plume is considered in the model. A significant but short term depletion of ozone is predicted, which is 99% restored in about 1 h in the wide plume with enhanced horizontal dispersion, but requires more than 24 h in the narrow plume without it. The oxidation rate of NO and NO2 into the HNO3 depends on the OH content in the exhausts and varies in all the cases. The heterogeneous photochemistry has only a small influence on the initial evolution of N2O5 and HO2 in the plume.

scholarly journals Horizontal Dispersion of Buoyant Materials in the Ocean Surface Boundary Layer

2018 ◽  
Vol 48 (9) ◽  
pp. 2103-2125 ◽  
Author(s):  
Jun-Hong Liang ◽  
Xiaoliang Wan ◽  
Kenneth A. Rose ◽  
Peter P. Sullivan ◽  
James C. McWilliams
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Ocean Surface ◽  
Turbulent Dispersion ◽  
Surface Boundary ◽  
Particle Trajectories ◽  
Stokes Flows ◽  
Surface Boundary Layer ◽  
Horizontal Dispersion ◽  
Shear Dispersion

ABSTRACTThe horizontal dispersion of materials with a constant rising speed under the exclusive influence of ocean surface boundary layer (OSBL) flows is investigated using both three-dimensional turbulence-resolving Lagrangian particle trajectories and the classical theory of dispersion in bounded shear currents generalized for buoyant materials. Dispersion in the OSBL is caused by the vertical shear of mean horizontal currents and by the turbulent velocity fluctuations. It reaches a diffusive regime when the equilibrium vertical material distribution is established. Diffusivity from the classical shear dispersion theory agrees reasonably well with that diagnosed using three-dimensional particle trajectories. For weakly buoyant materials that can be mixed into the boundary layer, shear dispersion dominates turbulent dispersion. For strongly buoyant materials that stay at the ocean surface, shear dispersion is negligible compared to turbulent dispersion. The effective horizontal diffusivity due to shear dispersion is controlled by multiple factors, including wind speed, wave conditions, vertical diffusivity, mixed layer depth, latitude, and buoyant rising speed. With all other meteorological and hydrographic conditions being equal, the effective horizontal diffusivity is larger in wind-driven Ekman flows than in wave-driven Ekman–Stokes flows for weakly buoyant materials and is smaller in Ekman flows than in Ekman–Stokes flows for strongly buoyant materials. The effective horizontal diffusivity is further reduced when enhanced mixing by breaking waves is included. Dispersion by OSBL flows is weaker than that by submesoscale currents at a scale larger than 100 m. The analytic framework will improve subgrid-scale modeling in realistic particle trajectory models using currents from operational ocean models.

scholarly journals Effects of vertical shear in modelling horizontal oceanic dispersion

Ocean Science ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 207-216 ◽  
Author(s):  
A. S. Lanotte ◽  
R. Corrado ◽  
L. Palatella ◽  
C. Pizzigalli ◽  
I. Schipa ◽  
...  
Keyword(s):  
Marine Biology ◽  
Mixing Layer ◽  
Pollutant Dispersion ◽  
Ocean Model ◽  
Three Dimensions ◽  
Vertical Shear ◽  
Time Variability ◽  
Horizontal Dispersion ◽  
Forecasting System ◽  
The Mediterranean

Abstract. The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

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