Turbulent Mixing in a Far‐Field Plume During the Transition to Upwelling Conditions: Microstructure Observations From an AUV

Fisher, Alexander W.; Nidzieko, Nicholas J.; Scully, Malcolm E.; Chant, Robert J.; Hunter, Elias; Mazzini, Piero L. F.

doi:10.1029/2018gl078543

Cited by 9 publications

(20 citation statements)

References 39 publications

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“…As already mentioned before, the Thorpe scale ( L T is an empirical measure of turbulent vertical overturns that can be obtained from a careful operation of regular CTD profilers or moored temperature measurements. For this reason, the length-scale method is popular across a wide range of ocean and lake studies 10 , 11 , 78 , 79 . However, it is increasingly recognized that a simple scaling between L T and L O may not be generally applicable, as the ratio between the two scales varies across the different stages of a turbulent event 80 .…”

Section: Usage Notesmentioning

confidence: 99%

A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

et al. 2021

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A multi-site, year-round dataset comprising a total of 606 high-resolution turbulence microstructure profiles of shear and temperature gradient in the upper 100 m depth is made available for Lake Garda (Italy). Concurrent meteorological data were measured from the fieldwork boat at the location of the turbulence measurements. During the fieldwork campaign (March 2017-June 2018), four different sites were sampled on a monthly basis, following a standardized protocol in terms of time-of-day and locations of the measurements. Additional monitoring activity included a 24-h campaign and sampling at other sites. Turbulence quantities were estimated, quality-checked, and merged with water quality and meteorological data to produce a unique turbulence atlas for a lake. The dataset is open to a wide range of possible applications, including research on the variability of turbulent mixing across seasons and sites (demersal vs pelagic zones) and driven by different factors (lake-valley breezes vs buoyancy-driven convection), validation of hydrodynamic lake models, as well as technical studies on the use of shear and temperature microstructure sensors.

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Section: Usage Notesmentioning

confidence: 99%

A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

et al. 2021

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“…Buoyant river plumes are typical coastal features transitioning the continental runoff into shelf waters. These surface-advected sub-mesoscale and mesoscale structures are generally characterized by, first, more intense motion in response to external forcing as compared to ambient coastal circulation and, second, stronger stratification that leads to reduced mixing between the surface layer and deeper waters (Garvine, 1984;Garvine, 1995;Cole and Hetland, 2015;Mazzini and Chant, 2016;Fisher et al, 2018;Mazzini et al, 2019). As a result, buoyant river plumes can effectively transport large volumes of freshwater, terrigenous sediments, nutrients, carbon, litter, and anthropogenic pollutants from tens to hundreds Lemos et al of kilometers away from the river mouths.…”

Section: Introductionmentioning

confidence: 99%

Spreading and accumulation of river-borne sediments in the coastal ocean after the environmental disaster at the Doce River in Brazil

et al. 2022

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This study is focused on the fate of a large volume of mine slurry discharged from the Doce River (DR) to the coastal ocean after the worst environmental disaster in Brazilian which occurred in November 2015. We used Eulerian (ROMS) and Lagrangian (STRiPE) numerical models, as well as satellite remote sensing data, to study the spreading and seafloor accumulation of fine river-borne sediments during the initial six months following the disaster. We show that the regions of intense sediment accumulation were determined by spreading patterns of the surface-advected DR plume. The river discharge rate governed the plume surface area, while its position depended on local wind forcing conditions. The spreading of sediments carried by the DR plume was dominated by southward transport caused by prevailing upwelling-favorable northeasterly winds during the study period. Under high discharge conditions, river-borne sediments were transported over 100 km southward from the DR mouth and reached the outer shelf. In contrast, sediments were arrested near the mouth during drought periods and remained on the inner shelf. As a result, fine river-borne sediments accumulated on the seafloor, mainly in the large shallow shelf area southward from the DR mouth. Conversely, only a small fraction of residue was deposited northward. Thus, the Environmental Protection Area (EPA) of Costa das Algas, located 40 km southward from the DR, potentially exhibited more susceptibility to sediment arrival. On the other hand, their influence on Abrolhos Marine National Park, located 200 km northeastward from the DR mouth, was presumably minimal.

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“…These include the Ocean Explorer, REMUS AUV, and Glider, etc. [8][9][10][11][12], whose dissipation rates are as low as 10 −10 W kg −1 . The AUV has flexible mission types, which can realize horizontal, vertical, as well as bottom and surface observation tasks.…”

Section: Introductionmentioning

confidence: 99%

Design and Motion Performance Analysis of Turbulent AUV Measuring Platform

Nie

Song

Wang

et al. 2022

Sensors

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The use of a multi-functional autonomous underwater vehicle (AUV) as a platform for making turbulence measurements in the ocean is developed. The layout optimization of the turbulence package and platform motion performance are limitation problems in turbulent AUV design. In this study, the computational fluid dynamics (CFD) method has been used to determine the optimized layout position and distance of the shear probe integrated into an AUV. When placed 0.8 D ahead of the AUV nose along the axis, the shear probe is not influenced by flow distortion and can contact the water body first. To analyze the motion of the turbulence AUV, the dynamic model of turbulence AUV for planar flight is obtained. Then, the mathematical equations of speed and angle of attack under steady-state motion have also been obtained. By calculating the hydrodynamic coefficients of the turbulence AUV and given system parameters, the simulation analysis has been conducted. The simulation results demonstrated that the speed of turbulent AUV is 0.5–1 m/s, and the maximum angle of attack is less than 6.5°, which meets the observation requirements of the shear probe. In addition, turbulence AUV conducted a series of sea-trials in the northern South China Sea to illustrate the validity of the design and measurement. Two continuous profiles (1000 m) with a horizontal distance of 10 km were completed, and numerous high-quality spatiotemporal turbulence data were obtained. These profiles demonstrate the superior flight performance of turbulence AUV. Analysis shows that the measured data are of high quality, with the shear spectra being in very good agreement with the Nasmyth spectrum. Dissipation rates are consistent with background shear. When shear velocity is weak, the measurement of dissipation rate is 10−10 W Kg−1. All indications are that the turbulence AUV is suitable for long-term, contiguous ocean microstructure measurements, which will provide data needed to understand the temporal and spatial variability of the turbulent processes in the oceans.

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Turbulent Mixing in a Far‐Field Plume During the Transition to Upwelling Conditions: Microstructure Observations From an AUV

Cited by 9 publications

References 39 publications

A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

Spreading and accumulation of river-borne sediments in the coastal ocean after the environmental disaster at the Doce River in Brazil

Design and Motion Performance Analysis of Turbulent AUV Measuring Platform

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