scholarly journals Turbulent mixing process in the Lombok Strait

2021 ◽  
Vol 944 (1) ◽  
pp. 012067
Author(s):  
Y Naulita ◽  
N M N Natih ◽  
Nabil
Keyword(s):  
Turbulent Mixing ◽  
Eddy Diffusivity ◽  
Energy Dissipation Rate ◽  
Shear Instability ◽  
Mixing Process ◽  
Strong Shear ◽  
Ozmidov Scale ◽  
Thorpe Scale ◽  
The Indian Ocean

Abstract Turbulent mixing process in the Lombok Strait was evaluated from density inversions in CTD (Conductivity Temperature Depth) profiles obtained from the INSTANT (International Nusantara Stratification and Transport) recovery cruise, June 14-19th 2005. The quality of the detected-overturn regions has been improved by applying wavelet denoising to CTD signals. The Thorpe analysis shows that many overturn regions less than 7 m were detected in throughout the water column of the Lombok Strait. Based on linear relationship between Thorpe Scale and Ozmidov Scale, the turbulent kinetic energy dissipation rate ε was estimated about 10−12−10−6 W kg−1 and density of eddy diffusivity Kρ (10−6−10−2 m2s −1). A relatively high of Kρ Ø (10−2 m2s −1) was found at the southern part of the strait, near the sill which obstruct the Indonesian Thoughflow into the Indian Ocean. The dipped and rebounded isopycnal surfaces of σθ= 25.5–26.5 near the sill and the presence of strong shear at the same depth of the interval solitary wave (150 to 250 m) indicate that strong turbulence in this layer was driven by shear instability associated with breaking internal waves.

scholarly journals TURBULENT MIXING PROCESSES IN LABANI CHANNEL, THE MAKASSAR STRAIT

2016 ◽  
Vol 8 (1) ◽  
Author(s):  
Yuli Naulita
Keyword(s):  
Turbulent Mixing ◽  
Eddy Diffusivity ◽  
Turbulent Energy ◽  
Wavelet Denoising ◽  
Mixing Processes ◽  
Ozmidov Scale ◽  
Thorpe Scale ◽  
Order Of Magnitude ◽  
O 10 ◽  
Temperature Depth

<p><em>Study on turbulent mixing processes in Labani Channel, the Makassar Strait, was conducted by using the INSTANT (International Nusantara Stratification And Transport) program dataset, in Juli 2005. The turbulent mixing process was evaluated using Thorpe method, where the overturning eddies were revealed by density inversions in CTD (Conductivity Temperature Depth) profiles. All individual identified-overturn regions was validated by the GK’s test (Galbraith and Kelly test) where at first noise on CTD signals had been removed  by applying wavelet denoising.   A large number of overturn regions with Thorpe scale (L<sub>T</sub>) less than 0.5 m were detected in the thermocline layer of Makassar Strait. Based on linear relationship between Thorpe and Ozmidov scale, order of magnitude of the turbulent energy kinetic dissipation rate in Labani Channel was estimated about </em><em>10<sup>-11</sup>- 10<sup>-5</sup>Wkg<sup>-1</sup> and </em><em>density eddy diffusivity K<sub>ρ</sub></em><em>(10<sup>-6  </sup>– 10<sup>-2</sup>) m<sup>2</sup>/s . The strong of turbulen mixing was found at the layer of  NPSW at 150 m depth and NPIW at 300 m depth, indicated by high values of K<sub>ρ </sub> (O = 10<sup>-3</sup> – 10<sup>-2</sup> m<sup>2</sup>s<sup>-1</sup>).  It reveals that turbulent mixing has an important role on determining ITF water mass character.  </em></p><p><strong><em>Keywoods</em></strong><em>: turbulent mixing, wavelet denoising, overturn region, Thorpe method, Labani Channel, Makassar Srait.</em></p>

scholarly journals TURBULENT MIXING PROCESSES IN LABANI CHANNEL, THE MAKASSAR STRAIT

2016 ◽  
Vol 8 (1) ◽  
pp. 345-355 ◽  
Author(s):  
Yuli Naulita
Keyword(s):  
Turbulent Mixing ◽  
Eddy Diffusivity ◽  
Turbulent Energy ◽  
Wavelet Denoising ◽  
Mixing Processes ◽  
Ozmidov Scale ◽  
Thorpe Scale ◽  
Order Of Magnitude ◽  
O 10 ◽  
Temperature Depth

Study on turbulent mixing processes in Labani Channel, the Makassar Strait, was conducted by using the INSTANT (International Nusantara Stratification And Transport) program dataset, in Juli 2005. The turbulent mixing process was evaluated using Thorpe method, where the overturning eddies were revealed by density inversions in CTD (Conductivity Temperature Depth) profiles. All individual identified-overturn regions was validated by the GK’s test (Galbraith and Kelly test) where at first noise on CTD signals had been removed  by applying wavelet denoising.   A large number of overturn regions with Thorpe scale (LT) less than 0.5 m were detected in the thermocline layer of Makassar Strait. Based on linear relationship between Thorpe and Ozmidov scale, order of magnitude of the turbulent energy kinetic dissipation rate in Labani Channel was estimated about 10-11- 10-5Wkg-1 and density eddy diffusivity Kρ(10-6  – 10-2) m2/s . The strong of turbulen mixing was found at the layer of  NPSW at 150 m depth and NPIW at 300 m depth, indicated by high values of Kρ  (O = 10-3 – 10-2 m2s-1).  It reveals that turbulent mixing has an important role on determining ITF water mass character.  Keywoods: turbulent mixing, wavelet denoising, overturn region, Thorpe method, Labani Channel, Makassar Srait.

scholarly journals Improving lake mixing process simulations in the Community Land Model by using <i>K</i> profile parameterization

2019 ◽  
Vol 23 (12) ◽  
pp. 4969-4982 ◽  
Author(s):  
Qunhui Zhang ◽  
Jiming Jin ◽  
Xiaochun Wang ◽  
Phaedra Budy ◽  
Nick Barrett ◽  
...  
Keyword(s):  
Vertical Mixing ◽  
Eddy Diffusivity ◽  
Shear Instability ◽  
The Tibetan Plateau ◽  
Mixing Process ◽  
Water Mixing ◽  
Community Land Model ◽  
Lake Mixing ◽  
Lake Model ◽  
Process Simulations

Abstract. We improved lake mixing process simulations by applying a vertical mixing scheme, K profile parameterization (KPP), in the Community Land Model (CLM) version 4.5, developed by the National Center for Atmospheric Research. Vertical mixing of the lake water column can significantly affect heat transfer and vertical temperature profiles. However, the current vertical mixing scheme in CLM requires an arbitrarily enlarged eddy diffusivity to enhance water mixing. The coupled CLM-KPP considers a boundary layer for eddy development, and in the lake interior water mixing is associated with internal wave activity and shear instability. We chose a lake in Arctic Alaska and a lake on the Tibetan Plateau to evaluate this improved lake model. Results demonstrated that CLM-KPP reproduced the observed lake mixing and significantly improved lake temperature simulations when compared to the original CLM. Our newly improved model better represents the transition between stratification and turnover. This improved lake model has great potential for reliable physical lake process predictions and better ecosystem services.

scholarly journals WAVELET DENOISING APPLICATION ON CTD (CONDUCTIVITY TEMPERATURE DEPTH) SIGNALS TO IMPROVE THE QUALITY OF IDENTIFIED OVERTURN REGION

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
Yuli Naulita
Keyword(s):  
Small Perturbation ◽  
Turbulent Mixing ◽  
Wavelet Denoising ◽  
Density Gradients ◽  
Mixing Process ◽  
Processing Data ◽  
Small Density ◽  
Temperature Depth

<p>Turbulent mixing process can be evaluated from density inversions in CTD profiles, that may reveal the overturning eddies. The quality of overturn regions are then determined by the quality of CTD signals. The study removed noise on CTD signals without losing small perturbation which commonly occurred by traditional filter.   By applying wavelet denoising in pre-processing data of Thorpe method, more Thorpe displacements indicated overturn regions, were able to detect especially in small density gradients. Therefore, the identified overturn region using the Thorpe method can be applied to a larger region of density gradients.</p> <p>Keywoods: turbulent mixing, overturn, Thorpe method, Thorpe displacement, wavelet denoising.</p>

scholarly journals WAVELET DENOISING APPLICATION ON CTD (CONDUCTIVITY TEMPERATURE DEPTH) SIGNALS TO IMPROVE THE QUALITY OF IDENTIFIED OVERTURN REGION

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
Yuli Naulita
Keyword(s):  
Small Perturbation ◽  
Turbulent Mixing ◽  
Wavelet Denoising ◽  
Density Gradients ◽  
Mixing Process ◽  
Processing Data ◽  
Small Density ◽  
Temperature Depth

Turbulent mixing process can be evaluated from density inversions in CTD profiles, that may reveal the overturning eddies. The quality of overturn regions are then determined by the quality of CTD signals. The study removed noise on CTD signals without losing small perturbation which commonly occurred by traditional filter.   By applying wavelet denoising in pre-processing data of Thorpe method, more Thorpe displacements indicated overturn regions, were able to detect especially in small density gradients. Therefore, the identified overturn region using the Thorpe method can be applied to a larger region of density gradients. Keywoods: turbulent mixing, overturn, Thorpe method, Thorpe displacement, wavelet denoising.

scholarly journals Vertical fluxes of nutrients enhanced by strong turbulence and phytoplankton bloom around the ocean ridge in the Luzon Strait

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Eisuke Tsutsumi ◽  
Takeshi Matsuno ◽  
Sachihiko Itoh ◽  
Jing Zhang ◽  
Tomoharu Senjyu ◽  
...  
Keyword(s):  
Surface Layer ◽  
Turbulent Mixing ◽  
Phytoplankton Bloom ◽  
Marine Ecosystem ◽  
Euphotic Zone ◽  
Eddy Diffusivity ◽  
Energy Dissipation Rate ◽  
Luzon Strait ◽  
New Production ◽  
Ocean Ridge

Abstract Steep oceanic ridges and tidal currents in the Luzon Strait generate some of the world’s strongest turbulent mixing. To evaluate the impacts of the turbulence intensity on the marine ecosystem, we carried out measurements of microstructure turbulence and biogeochemical hydrography along 21°N in the Luzon Strait during the R/V Hakuho Maru cruise, KH-17-5-2, in November 2017. We found a turbulent kinetic energy dissipation rate exceeding O(10−7) W kg−1 and vertical eddy diffusivity exceeding O(10−3) m2 s−1, two orders of magnitude larger than those in the open ocean, above a shallow sub-ridge on the eastern ridge of the Luzon Strait. In addition, a clear chlorophyll a bloom was identified in the surface layer above the sub-ridge from in situ measurements and satellite observations. High values of nitrate (4.7 mmol N m−2 d−1) and phosphate (0.33 mmol P m−2 d−1) fluxes estimated near the base of the surface chlorophyll a bloom strongly suggest that enhanced turbulent mixing promotes nutrient supply to the euphotic zone and generates new production within the surface layer, contributing to the formation of a quasi-permanent local chlorophyll a bloom north of Itbayat Island on the eastern ridge.

Model Pemberdayaan Usaha Mikro Dan Pengaruhnya Terhadap Kemandirian Usaha

2015 ◽  
Vol 2 (1) ◽  
pp. 75-93
Author(s):  
Mudasetia Hamid ◽  
Evy Rosalina Widyayanti
Keyword(s):  
Human Resources ◽  
Small And Medium Enterprises ◽  
Poverty Rate ◽  
Cultural Centers ◽  
Central Java ◽  
Tourism Education ◽  
The Indian Ocean ◽  
Medium Enterprises ◽  
The City

Yogyakarta is a city and the capital of Yogyakarta Special Region in Java, Indonesia. It is renowned as a center of tourism, education and culture. Yogyakarta is one of the foremost cultural centers of Java. This region is located at the foot of the active merapi vulcano. Yogyakarta is often called the main gateway to the Central Java as where it is geographically located. It stretches from Mount Merapi to the Indian Ocean. This province is one of the most densely populated areas of Indonesia. Yogyakarta is popular tourist destination in indonesia after Bali. These have attracted large number of visitors from across Indonesia and abroad to the city. This status makes Yogyakarta is one of the most heterogeneus cities in Indonesia. In edition, Yogyakarta has attracted large number of people to reside in this city for business. One of these comers is small entrepreneurs with their market munchies enterprise (specially a traditional snack trader). This business is one of famous business in Yogyakarta, we will find rows of pavement vendors selling market munchies. The students and tourists are their main target customers. Market munchies enterprise is part of small and medium enterprises SMEs as livelihood activities. SMEs has an important role in economic growth of Indonesia. Therefore, it is very important to develop and strengthen the micro enterprise empowerment. Micro enterprise empowerment is one of strategy to reduce the poverty rate in Indonesia. Major challenger in implement this program are that micro entrepreneurs are conventional and have satisfied with their revenue. It is very important to develop a comprehensive and sustainable micro enterprise empowerment which consist of strengthen the quality of human resources, maximize the government’s roles, empower the enterprise capital and strengthen the partnership and autonomous. Micro enterprise autonomy will contribute to the economic and investment climate. This will lead to establish an accountable enterprise both for the micro enterprise and customers which at the end will strengthen the development of the micro enterprise in Yogyakarta.Keyword: micro entreprise, human resources, government roles, capital, partnership and autonomous.

Frontogenesis and frontal arrest of a dense filament in the oceanic surface boundary layer

2017 ◽  
Vol 837 ◽  
pp. 341-380 ◽  
Author(s):  
Peter P. Sullivan ◽  
James C. McWilliams
Keyword(s):  
Boundary Layer ◽  
Turbulent Mixing ◽  
Shear Instability ◽  
Upper Ocean ◽  
Surface Boundary ◽  
Horizontal Shear ◽  
Boundary Layer Turbulence ◽  
Filament Axis ◽  
Small Width ◽  
The Cross

The evolution of upper ocean currents involves a set of complex, poorly understood interactions between submesoscale turbulence (e.g. density fronts and filaments and coherent vortices) and smaller-scale boundary-layer turbulence. Here we simulate the lifecycle of a cold (dense) filament undergoing frontogenesis in the presence of turbulence generated by surface stress and/or buoyancy loss. This phenomenon is examined in large-eddy simulations with resolved turbulent motions in large horizontal domains using${\sim}10^{10}$grid points. Steady winds are oriented in directions perpendicular or parallel to the filament axis. Due to turbulent vertical momentum mixing, cold filaments generate a potent two-celled secondary circulation in the cross-filament plane that is frontogenetic, sharpens the cross-filament buoyancy and horizontal velocity gradients and blocks Ekman buoyancy flux across the cold filament core towards the warm filament edge. Within less than a day, the frontogenesis is arrested at a small width,${\approx}100~\text{m}$, primarily by an enhancement of the turbulence through a small submesoscale, horizontal shear instability of the sharpened filament, followed by a subsequent slow decay of the filament by further turbulent mixing. The boundary-layer turbulence is inhomogeneous and non-stationary in relation to the evolving submesoscale currents and density stratification. The occurrence of frontogenesis and arrest are qualitatively similar with varying stress direction or with convective cooling, but the detailed evolution and flow structure differ among the cases. Thus submesoscale filament frontogenesis caused by boundary-layer turbulence, frontal arrest by frontal instability and frontal decay by forward energy cascade, and turbulent mixing are generic processes in the upper ocean.

scholarly journals Evaluation of Forecasts of a Convectively Generated Bore Using an Intensively Observed Case Study from PECAN

2018 ◽  
Vol 146 (9) ◽  
pp. 3097-3122 ◽  
Author(s):  
Aaron Johnson ◽  
Xuguang Wang ◽  
Kevin R. Haghi ◽  
David B. Parsons
Keyword(s):  
Cross Sections ◽  
Turbulent Mixing ◽  
Weather Research And Forecasting ◽  
Cold Pool ◽  
Model Errors ◽  
Near Surface ◽  
Cold Pools ◽  
Convection Model

Abstract This paper presents a case study from an intensive observing period (IOP) during the Plains Elevated Convection at Night (PECAN) field experiment that was focused on a bore generated by nocturnal convection. Observations from PECAN IOP 25 on 11 July 2015 are used to evaluate the performance of high-resolution Weather Research and Forecasting Model forecasts, initialized using the Gridpoint Statistical Interpolation (GSI)-based ensemble Kalman filter. The focus is on understanding model errors and sensitivities in order to guide forecast improvements for bores associated with nocturnal convection. Model simulations of the bore amplitude are compared against eight retrieved vertical cross sections through the bore during the IOP. Sensitivities of forecasts to microphysics and planetary boundary layer (PBL) parameterizations are also investigated. Forecasts initialized before the bore pulls away from the convection show a more realistic bore than forecasts initialized later from analyses of the bore itself, in part due to the smoothing of the existing bore in the ensemble mean. Experiments show that the different microphysics schemes impact the quality of the simulations with unrealistically weak cold pools and bores with the Thompson and Morrison microphysics schemes, cold pools too strong with the WDM6 and more accurate with the WSM6 schemes. Most PBL schemes produced a realistic bore response to the cold pool, with the exception of the Mellor–Yamada–Nakanishi–Niino (MYNN) scheme, which creates too much turbulent mixing atop the bore. A new method of objectively estimating the depth of the near-surface stable layer corresponding to a simple two-layer model is also introduced, and the impacts of turbulent mixing on this estimate are discussed.

scholarly journals Observations of Turbulence in Free Atmosphere by Balloon-Borne Sensors

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3273
Author(s):  
Lesong Zhou ◽  
Zheng Sheng ◽  
Qixiang Liao
Keyword(s):  
Large Scale ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Sensor Data ◽  
Free Atmosphere ◽  
Height Range ◽  
High Latitude Region ◽  
Thorpe Scale ◽  
Scale Turbulence ◽  
Turbulence Parameters

In recent years, Thorpe analysis has been used to retrieve the characteristics of turbulence in free atmosphere from balloon-borne sensor data. However, previous studies have mainly focused on the mid-high latitude region, and this method is still rarely applied at heights above 30 km, especially above 35 km. Therefore, seven sets of upper air (>35 km) sounding data from the Changsha Sounding Station (28°12′ N, 113°05′ E), China are analyzed with Thorpe analysis in this article. It is noted that, in the troposphere, Thorpe analysis can better retrieve the turbulence distribution and the corresponding turbulence parameters. Also, because of the thicker troposphere at low latitudes, the values of the Thorpe scale L T and turbulent energy dissipation rate ε remain greater in a larger height range. In the stratosphere below the height of 35 km, the obtained ε is higher, and Thorpe analysis can only be used to analyze the characteristics of large-scale turbulence. In the stratosphere at a height of 35–40 km, because of the interference of sensor noise, Thorpe analysis can only help to retrieve the rough distribution position of large-scale turbulence, while it can hardly help with the calculation of the turbulence parameters.

Sign in / Sign up

Export Citation Format

Share Document