Mixing efficiency from microstructure measurements in the Sicily Channel

Vladoiu, Anda; Bouruet‐Aubertot, Pascale; Cuypers, Yannis; Ferron, Bruno; Schröeder, Katrin; Borghini, Mireno; Leizour, Stéphane; Ismail, Sana Ben

doi:10.1007/s10236-019-01274-2

Cited by 11 publications

(6 citation statements)

References 78 publications

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“…They found that the variation of mixing efficiency with the Richardson number strongly depended on the background buoyancy profile, and that the mixing efficient has a maximum value of 0.25, which agreed well with predictions based on the more usual kinematics-based approach. This is consistent with measurements from the field [29] and laboratory [30].…”

Section: Introductionsupporting

confidence: 90%

The Multi-Scale Layering-Structure of Thermal Microscale Profiles

Folkard¹

2021

Water

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Thermal microstructure profiling is an established technique for investigating turbulent mixing and stratification in lakes and oceans. However, it provides only quasi-instantaneous, 1-D snapshots. Other approaches to measuring these phenomena exist, but each has logistic and/or quality weaknesses. Hence, turbulent mixing and stratification processes remain greatly under-sampled. This paper contributes to addressing this problem by presenting a novel analysis of thermal microstructure profiles, focusing on their multi-scale stratification structure. Profiles taken in two small lakes using a Self-Contained Automated Micro-Profiler (SCAMP) were analysed. For each profile, buoyancy frequency (N), Thorpe scales (LT), and the coefficient of vertical turbulent diffusivity (KZ) were determined. To characterize the multi-scale stratification, profiles of d2T/dz2 at a spectrum of scales were calculated and the number of turning points in them counted. Plotting these counts against the scale gave pseudo-spectra, which were characterized by the index D of their power law regression lines. Scale-dependent correlations of D with N, LT and KZ were found, and suggest that this approach may be useful for providing alternative estimates of the efficiency of turbulent mixing and measures of longer-term averages of KZ than current methods provide. Testing these potential uses will require comparison of field measurements of D with time-integrated KZ values and numerical simulations.

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Section: Introductionsupporting

confidence: 90%

The Multi-Scale Layering-Structure of Thermal Microscale Profiles

Folkard¹

2021

Water

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“…Under such a condition, two estimates of e were averaged. Otherwise, we used the estimate of e with a smaller value (Vladoiu et al, 2019). The estimated e values over 0-5 m were excluded due to the contamination of the ship's wake.…”

Section: Methodsmentioning

confidence: 99%

Mixing in the upper western equatorial Pacific driven by westerly wind event

et al. 2023

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Diapycnal mixing in the upper western equatorial Pacific (WEP) plays an important role in the tropical air–sea interactions and in the formation of the global climate system. Yet, the WEP is uniquely rich in water masses originating from the two hemispheres and in multiscale processes of different dynamical nature, thus creating a complex regime of mixing remains to be fully characterized by elaborate observations. Here, on the basis of microstructure measurements in the WEP, we report the observations on a strong deep cycle turbulence extending well into the upper thermocline by westerly wind event, with the turbulent kinetic energy dissipation rate ε~O(10−8–10−7) W kg−1 and diapycnal diffusivity Kρ∼O(10−4) m2 s−1. Below the deep cycle turbulence layer, turbulence and mixing are generally weak with ε~O(10−10–10−9) W kg−1 and Kρ∼O(10−7–10−6) m2 s−1, a prototype of the weak mixing nature of the low-latitude western Pacific. The observed turbulence below the deep cycle turbulence layer can be satisfactorily scaled by either the MacKinnon–Gregg model or the Richardson number–based model with tuned model parameters.

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“…These sensors are designed to be distributed as dense arrays over the surface of a body travelling underwater, thus enabling a better spatial description of the parameters of interest, as well as accurate prognostic of the state of the robots, for the purpose of control and localization. Given the importance that turbulence measurements of microstructure hold in the understanding of the nature of energy dissipation in the ocean, 118 these new breed of sensors may unveil an unprecedented degree of information.…”

Section: Applicationsmentioning

confidence: 99%

Soft Robots for Ocean Exploration and Offshore Operations: A Perspective

et al. 2021

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The ocean and human activities related to the sea are under increasing pressure due to climate change, widespread pollution, and growth of the offshore energy sector. Data, in under-sampled regions of the ocean and in the offshore patches where the industrial expansion is taking place, are fundamental to manage successfully a sustainable development and to mitigate climate change. Existing technology cannot cope with the vast and harsh environments that need monitoring and sampling the most. The limiting factors are, among others, the spatial scales of the physical domain, the high pressure, and the strong hydrodynamic perturbations, which require vehicles with a combination of persistent autonomy, augmented efficiency, extreme robustness, and advanced control. In light of the most recent developments in soft robotics technologies, we propose that the use of soft robots may aid in addressing the challenges posed by abyssal and wave-dominated environments. Nevertheless, soft robots also allow for fast and low-cost manufacturing, presenting a new potential problem: marine pollution from ubiquitous soft sampling devices. In this study, the technological and scientific gaps are widely discussed, as they represent the driving factors for the development of soft robotics. Offshore industry supports increasing energy demand and the employment of robots on marine assets is growing. Such expansion needs to be sustained by the knowledge of the oceanic environment, where large remote areas are yet to be explored and adequately sampled. We offer our perspective on the development of sustainable soft systems, indicating the characteristics of the existing soft robots that promote underwater maneuverability, locomotion, and sampling. This perspective encourages an interdisciplinary approach to the design of aquatic soft robots and invites a discussion about the industrial and oceanographic needs that call for their application.

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Mixing efficiency from microstructure measurements in the Sicily Channel

Cited by 11 publications

References 78 publications

The Multi-Scale Layering-Structure of Thermal Microscale Profiles

The Multi-Scale Layering-Structure of Thermal Microscale Profiles

Mixing in the upper western equatorial Pacific driven by westerly wind event

Soft Robots for Ocean Exploration and Offshore Operations: A Perspective

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