Turbulence at the periphery of Sri Lanka dome

Lozovatsky, Iossif; Pirro, Annunziata; Jarosz, Ewa; Wijesekera, H. W.; Jinadasa, S.U.P.; Fernando, Harindra J. S.

doi:10.1016/j.dsr2.2019.07.002

Cited by 10 publications

(6 citation statements)

References 28 publications

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“…follows the formula for K N (Ri) given in Lozovatsky et al (2019b), with Ri cr 0.25 and a similar value of K 0 1.21 × 10 −4 m 2 s −1 , but an increased value of K b 7 × 10 −6 m 2 s −1 .…”

Section: Pycnocline Mixingmentioning

confidence: 53%

“…Even the median values of the dissipation rate ε ∼ 10 −8 W kg −1 are high compared to data collected in open-ocean regions, where turbulence generation is not directly affected by bathymetry unlike in the region close to the Nova Scotia shelf break. A comparison between the Nova Scotia measurements and data obtained recently in the deep waters of the Southern California Bight (SCB, Lozovatsky et al 2019a) and in the Sri Lanka dome region in the Bay of Bengal (SLD, Lozovatsky et al 2019b) is given in Fig. 8.…”

Section: Statistics Of the Richardson Number And The Dissipation Rate In The Pycnoclinementioning

confidence: 97%

“…Note that K b is thought to represent background diffusivity at Ri 1 when shear-induced turbulence is damped by stratification (Lozovatsky and Fernando 2013) and it is usually taken as K b 10 −6 m 2 s −1 (e.g., Peters et al 1988;Lozovatsky et al 2019b). A possible explanation for higher K b required to obtain the best fit of (1) to the data shown in Fig.…”

Section: Pycnocline Mixingmentioning

confidence: 99%

“…This, in combination with weak stratification in the pycnocline, led to frequent development of shear-induced turbulence perhaps associated with layers where the Richardson number Ri < Ri cr . Near the shelf break, 75% of data recorded showed Ri < 0.25 and 90% had Ri < 0.9, while in the pycnocline unaffected by dynamic processes at the shelf break (e.g., observations in the Bay of Bengal by Lozovatsky et al 2019b), only 5% of data showed Ri < 0.25 and less than 25% had Ri < 1. The frequency of occurrence of high dissipation events (ε > 10 −7 W kg −1 ) in the pycnocline exceeds ≈ 20% as compared to typical open-ocean values of 5-10%.…”

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confidence: 99%

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Ocean Turbulence and Mixing Near the Shelf Break South-East of Nova Scotia

Lozovatsky

Wainwright

Creegan

et al. 2020

Boundary-Layer Meteorol

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Formation of coastal fog was observed near the southern tip of Nova Scotia when warm, humid air was advected towards the shore over an area of colder water. The sea-surface temperature in the colder and higher salinity patch near the coast was below 14°C compared to that of the surrounding sea of ≈ 17-18°C. Measurements of stratification, currents, and the dissipation rate of turbulence kinetic energy (ε) on the Nova Scotia shelf, shelf break, and continental slope revealed the frequent occurrence of shear instability in the pycnocline. The probability of the gradient Richardson number (Ri) being less than a critical value of Ri cr 0.25 in the depth range 30-90 m exceeded 50% on the shelf and over the slope, and it was above 75% along the shelf break, while in the open ocean pycnocline the probability of Ri < 0.25 is below 5%. The cumulative distribution functions of the dissipation rate in the pycnocline south-east of Nova Scotia followed the Burr probability model with median values from 7.9 × 10 −9 W kg −1 on the slope to 1.9 × 10 −8 W kg −1 at the shelf break. The eddy diffusivity (K N ) estimates follow a generalized extreme value distribution with a high median value of K N 5.8 × 10 −5 m 2 s −1 at the shelf break. The diffusivity K N depended on Ri in general agreement with the parametrization previously suggested by Lozovatsky and Fernando (Philos Trans R Soc A 371:20120213, 2013) but with a higher level of mixing at Ri > 1. This could be relevant to the nature of turbulence generation near the shelf break by random wave instabilities in the pycnocline at high Richardson and high Reynolds numbers.

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Section: Pycnocline Mixingmentioning

confidence: 53%

Section: Statistics Of the Richardson Number And The Dissipation Rate In The Pycnoclinementioning

confidence: 97%

Section: Pycnocline Mixingmentioning

confidence: 99%

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confidence: 99%

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Ocean Turbulence and Mixing Near the Shelf Break South-East of Nova Scotia

Lozovatsky

Wainwright

Creegan

et al. 2020

Boundary-Layer Meteorol

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“…Until recently, only a few direct measurements of small-scale turbulence and related mixing in BoB have been conducted [11,15]. As a continuation of this works, in April and September of 2014, Sri Lankan oceanographers launched first ever measurements of microstructure and associated hydrodynamic variables (temperature, salinity, stratification, currents) to the south and to the east from the Sri Lanka coast (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Turbulence and Mixing in Energetic Environment of the Coastal Waters of Sri Lanka

Jinadasa

2021

OFOAJ

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In order to obtain first insights on the ocean turbulence and mixing in the waters around Sri Lanka, the microstructure measurements in the South Monsoon Current to the south of Weligama (along 80.5°E and near the shelf break) and in the East Indian Coastal Current in the Bay of Bengal to the east of Trincomalee (along 8°N) was conducted by National Aquatic Resources Research and Development Agency (NARA) of Sri Lanka aboard the research vessel Samuddrika. It is shown that in strongly startified pycnocline, which is dynamically detached from the low-saline surface mixed layer, the probability distributions of the logarithm of the kinetic energy dissipation rate 10 log ε follow generalized extreme value (GEV) model. This could be associated with the occurrence of rare highly-energetic turbulent patches in the pycnocline due to intermittent breaking of internal-wave and sporadic shear-induced instabilities. The mixing Reynolds number (a nomalized eddy diffusivity) was found to be a function of the gradient Richardson number, and followed the parameterization proposed by [1].

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