scholarly journals Indirect estimation of turbulent mixing in western route of Indonesian throughflow

2021 ◽  
Vol 944 (1) ◽  
pp. 012059
Author(s):  
M Firdaus ◽  
H Rahmawitri ◽  
S Haryoadji ◽  
A S Atmadipoera ◽  
Y Suteja ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Intermediate Water ◽  
Indonesian Throughflow ◽  
Pacific Water ◽  
Dissipation Energy ◽  
Tidal Waves ◽  
Water Characteristics ◽  
Vertical Diffusivity ◽  
Water Origin ◽  
Waves Interaction

Abstract The Indonesian Throughflow (ITF) via its western path conveys mainly North Pacific water origin with Smax thermocline water and Smin intermediate water from its entry portal in Sangihe-Talaud arcs to the main outflow straits in Lombok, Ombai and Timor passage. Along its route, the throughflow water characteristics transforms significantly due to strong diapycnal mixing forced by internal tidal waves interaction along complex topography such as passages, sill, straits, and shallow islands chains. This paper reports a brief estimate of turbulent mixing profiles in Sangihe chains, and Makassar Strait. The CTD dataset are obtained from the year of maritime continent (YMC) Cruise in August 2019 on board the R.V. Baruna Jaya I. The Thorpe method is used to analysis dissipation energy ( ε ) and vertical diffusivity (Kz ) from CTD dataset. It is shown that the highest ε epsilon 5.87 × 10−7 Wkg −1 and Kz 4.42 × 10−3 m2s 1 are found in the Sangihe area. In Labani Channel and Dewakang Sill the averaged vertical diffusivity is much weaker at the order of 10−4 m 2s1. Thus, Sangihe Chains station have the highest values compared to other stations at depth 950-1000 meters.

scholarly journals Transformation and mixing of North Pacific Water Mass in Sangihe-Talaud in August 2019

2021 ◽  
Vol 944 (1) ◽  
pp. 012053
Author(s):  
I Y Sani ◽  
A S Atmadipoera ◽  
A Purwandana ◽  
F Syamsudin
Keyword(s):  
Turbulent Mixing ◽  
North Pacific ◽  
Water Mass ◽  
Bottom Topography ◽  
Mass Composition ◽  
Intermediate Water ◽  
Interior Layer ◽  
Maritime Continent ◽  
Pacific Water ◽  
O 10

Abstract Along the pathway, ITF water is considered to be transformed due to strong diapycnal mixing. This study aims to describe the structure of ITF water and to estimate turbulent mixing. The number of 6 CTD casts and 9 repeated CTD “yoyo” measurements were obtained from the “Years of Maritime Continent” YMC cruise (a joint cruise between BPPT/IPB/UNUD-Univ. Tokyo/JAMSTEC) and onboard R.V. Baruna Jaya IV in August 2019. The CTD datasets are processed with SBE Data Processing and analyzed for water mass composition, as well as turbulent mixing with Thorpe method. The results showed that thermocline water of NPSW with S-max, and intermediate water of NPIW with S-min from North Pacific origin are dominant. Transformation of NPSW and NPIW along their pathway can be identified from decreasing S-max of NPSW and increasing S-min of NPIW. Estimates of ϵ and Kρ are O(10−5) m2s−2 and 10−2 m2 s−1, respectively. High mixing occur also in the interior layer with the e and the Kp O(10−6) m2s−2 and O(10−1) m2 s−1, respectively. This is related to barotropic tidal activity that interacts with the bottom topography where there are many sills, causing the formation of strong baroclinic tides.

scholarly journals Distribusi Percampuran Turbulen di Perairan Selat Alor (Distribution of Turbulence Mixing in Alor Strait)

2014 ◽  
Vol 19 (1) ◽  
pp. 43 ◽  
Author(s):  
Adi Purwandana ◽  
Mulia Purba ◽  
Agus S Atmadipoera
Keyword(s):  
Turbulent Mixing ◽  
Water Mass ◽  
Deep Layer ◽  
Bottom Topography ◽  
Eddy Diffusivity ◽  
Strong Mixing ◽  
Intermediate Water ◽  
Indonesian Throughflow ◽  
Average Value ◽  
Vertical Eddy

Selat Alor merupakan kanal terdalam setelah Selat Ombai di kepulauan Alor. Kontribusinya sebagai salah satu celah keluar Arus Lintas Indonesia (Arlindo) belum banyak dikaji hingga saat ini. Selat Alor memisahkan Laut Flores dan Laut Sawu, dan memiliki sill yang tinggi di dalamnya, diduga turbulensi akibat interaksi antara aliran selat dengan topografi dasar dapat memicu percampuran dan memodifikasi properti massa air yang melaluinya. Tujuan dari penelitian ini adalah untuk mengkuantifikasi transformasi massa air yang melalui Selat Alor dan mengkaji kemungkinan percampuran di dalam selat berdasarkan estimasi sesaat properti percampuran, yakni percampuran turbulen menggunakan metode skala Thorpe. Penurunan CTD dilakukan di 15 stasiun di perairan Selat Alor. Diperoleh hasil bahwa kontur kedalaman yang menghubungkan Laut Flores dengan Laut Sawu adalah ~300 m pada kanal utama. Salinitas maksimum massa air Subtropis Pasifik Utara (NPSW) dar i Laut Flores di Selat Alor banyak mengalami reduksi akibat intensifnya percampuran yang diduga dipicu oleh topografi dasar dan aliran selat yang menghasilkan turbulensi. Lapisan salinitas maksimum Massa Air Subtropis Samudera Hindia Utara (NISW) pada σθ = 23,5-24,5 terdeteksi di bagian selatan selat (Laut sawu). Jejak massa air NISW menurun dan banyak tereduksi mendekati pintu selatan selat. Intrusi Massa Air Lapisan Menengah Samudera Hindia Utara (NIIW) juga dijumpai di lapisan bawah Laut Sawu, konsisten dengan profil arus pada lapisan bawah. Rata-rata nilai difusivitas vertikal eddy (Kρ)  di Selat Alor bagian utara memiliki orde of 10-3 m2 s-1, dan di bagian selatan memiliki orde bervariasi, 10-6-10-4 m2 s-1. Penyempitan celah Selat Alor diduga merupakan pemicu turbulensi tinggi aliran yang berkontribusi pada tingginya nilai difusivitas vertikal. Kata kunci: Arlindo, percampuran turbulen, difusivitas vertikal, Selat Alor Alor Strait is the deepest channel in Alor islands after Ombai Strait. Contribution of the strait as one of the secondary exit passages of Indonesian Throughflow (ITF) has not been studied yet. The strait separates Flores Sea and Sawu Sea, and is featured by the existence of high sill within the strait, suggested that turbulence due to interaction between strait flow and bottom topography could drive mixing and then modify the water mass properties. The purpose of this study is to investigate transformation of ITF water mass and turbulent mixing process with Thorpe scale method. A hydrographic survey has been carried out in July 2011, in which 15 CTD casts were lowered in the strait. The results show that Alor sill depth is about 300 ms in the main gate. Maximum salinity of NPSW from Flores Sea within Alor Strait is significantly reduced due to strong mixing, perhaps driven by bottom topography and strait flow which creates turbulence. NISW (Northern Indian Subtropical Water) with maximum salinity layer at σθ = 23,5-24,5 is dominant in the southern part of Alor Strait (i.e. Sawu Sea). The existence of NIIW (North Indian Intermediate Water) is also found in the deeper layer of Sawu Sea. The average value of vertical eddy diffussivity (Kρ) estimate in the thermocline layer and deep layer in northern part and central part of strait channel is within the order of 10-3 m2 s-1. Lower order of Kρ in the thermocline layer and deep layer were found in southern part of the Strait (Sawu Sea), ranging from 10-6 to 10-4 m2 s-1. These indicate that the existence of sills in the northern part and central part of Alor Strait could drive mixing significantly. Narrowing passage of Alor Strait probably contribute to the high value of vertical eddy diffusivity due to highly turbulence flow. Keywords: Indonesian Throughflow (ITF), turbulent mixing, vertical diffussivity, Alor Strait

Turbulent Mixing in Raja Ampat Sea

2017 ◽  
Vol 862 ◽  
pp. 9-15 ◽  
Author(s):  
Aditya Pamungkas ◽  
Ivonne M. Radjawane ◽  
Hadikusumah
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Turbulent Mixing ◽  
Richardson Number ◽  
Complex Geometry ◽  
Energy Dissipation Rate ◽  
Diffusivity Coefficient ◽  
Indonesian Throughflow ◽  
Average Value ◽  
Vertical Diffusivity

Raja Ampat Sea has a complex geometry and passed by Indonesian Throughflow (ITF) causing a very dynamic water condition, that condition also amplified by turbulent mixing. To gain better understanding of process and extent of turbulent mixing in Raja Ampat Sea, this research calculate Brunt-Vaisala frequency, Richardson number, turbulent kinetic energy dissipation rate and vertical diffusivity coefficient. The data obtained from Expedition Widya Nusantara (EWIN) by P2O-LIPI in the territorial of Raja Ampat Sea on 14-24 November 2007, by using 12 out of 33 observation stations. From this research, it is known that in 0-40 m (mixed layer) and 250-400 m (deep layer) have Richardson number (Ri) less than 0.25 and high vertical diffusivity coefficient (Kv), It proves a strong turbulent mixing occurs at those depth. Furthermore, Raja Ampat Sea has strong turbulent mixing with average value of turbulent kinetic energy is 2.64 WKg-1and vertical diffusivity coefficient is 1.65x10-3 m2s.

scholarly journals WATER MASSES CHARACTERISTICS AT THE SANGHIE TALAUD ENTRY PASSAGE OF INDONESIAN THROUGHFLOW USING INDEX SATAL DATA 2010

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Ivonne M Radjawane ◽  
Paundra P Hadipoetranto
Keyword(s):  
North Pacific ◽  
Water Mass ◽  
Sea Water ◽  
Core Layer ◽  
South Pacific ◽  
New Guinea ◽  
Water Masses ◽  
Coastal Current ◽  
Indonesian Throughflow ◽  
Pacific Water

<p><strong><em>ABSTRACT</em></strong></p> <p><em>Measurement of ocean physical param</em><em>eter</em><em>s using the CTD was conducted by </em><em>deep water expedition </em><em>INDEX-SATAL 2010 (Indonesian Expedition Sangihe-Talaud) in July-August 2010. Th</em><em>e</em><em> </em><em>aim of this </em><em>study wa</em><em>s to</em><em> determine the characteristics of water masses around the Sangihe Talaud Water where the</em><em>re </em><em>wa</em><em>s an entry passage of </em><em> Indonesian throughflow (ITF) </em><em>at</em><em> </em><em>the </em><em>west </em><em>path</em><em>way that passed through the </em><em>primary</em><em> pathway i.e., </em><em>the Sulawesi</em><em> Sea and Makassar Strait and the secondary pathway (east pathway) that passed through the Halmahera Sea. The analyses were performed by the method of the core layer and was  processed with software Ocean Data View (ODV). The results showed that in the Sangihe Talaud waters there was a meeting water masses from the North Pacific and the South Pacific. The water mass characteristics in main pathway through the Sulawesi Sea was dominated by surface and intermediate North Pacific water masses and carried by the Mindanao Currents. While the Halmahera Sea water mass was dominated by surface and intermediate South Pacific water masses carried by the New Guinea Coastal Current that moved along the Papua New Guinea and Papua coast enters to the Halmahera Sea. </em></p> <p><em> </em></p> <p><strong><em>Keywords</em></strong><em>: Index-Satal 2010, Northern Pacific Water Mass</em><em>es</em><em>, Southern Pacific Water </em></p> <em> Masses, Sangihe Talaud</em>

scholarly journals Analysis of turbulent mixing in the Eastern Path of Indonesian Throughflow

2019 ◽  
Vol 278 ◽  
pp. 012003 ◽  
Author(s):  
D Adhyatma ◽  
A S Atmadipoera ◽  
Y Naulita ◽  
D Nugroho ◽  
Herlisman
Keyword(s):  
Turbulent Mixing ◽  
Indonesian Throughflow

Turbulent mixing limits mussel feeding: direct estimates of feeding rate and vertical diffusivity

2013 ◽  
Vol 485 ◽  
pp. 105-121 ◽  
Author(s):  
C Saurel ◽  
JK Petersen ◽  
PJ Wiles ◽  
MJ Kaiser
Keyword(s):  
Turbulent Mixing ◽  
Feeding Rate ◽  
Vertical Diffusivity

scholarly journals Percampuran Turbulen Di Laut Sulawesi Menggunakan Estimasi Thorpe Analisis

2021 ◽  
Vol 24 (2) ◽  
pp. 211-222
Author(s):  
Hadi Hermansyah ◽  
Agus Saleh Atmadipoera ◽  
Tri Prartono ◽  
Indra Jaya ◽  
Fadli Syamsudin
Keyword(s):  
Turbulent Mixing ◽  
Large Scale ◽  
Near Field ◽  
Tidal Energy ◽  
Eddy Diffusivity ◽  
Internal Tides ◽  
Strong Mixing ◽  
Ocean Energy ◽  
Average Value ◽  
Vertical Diffusivity

Dissipation of internal tides will cause mixing, The mixing process at sea plays a key role in controlling large-scale circulation and ocean energy distribution. The purpose of this research was to estimate the turbulent mixing values  (vertical eddy diffusivity) of water mass using Thorpe analysis. The results showed that the  location where strong mixing occurred in the “near-field” area around Sangihe Island with vertical diffusivity value . Even in areas far-field(far from the generating site) are found vertical diffusivity , the result of internal propagation tides dissipation. Based on the result of the observation, it shows that the level of kinetic energy of eddy turbulen dissipation (ε) in the Sulawesi Sea on all layers has an average value of . The value of ε in the thermocline layer is greatest  compared to the mixed surface layer and the almost homogeneous deep layer, the increase in mixing in the area near the ridge due to the closer water column to the base topography. The average turbulent rate of , the strongest fluctuation of value occurs in the thermocline layer, ranging from  to  with an average of about . The value of this turbulent mixing is higher than the previous measurements in some Indonesian ocean. This is allegedly due to the existence of a strong internal tidal energy and its interaction with topography in the Sulawesi Sea.Disipasi dari pasang surut internal akan menyebabkan terjadinya percampuran, proses percampuran di laut memainkan peran kunci dalam mengendalikan sirkulasi skala besar dan distribusi energi lautan. Tujuan dari penelitian ini adalah untuk mengestimasi nilai percampuran turbulen (difusivitas eddy vertikal) massa air dengan analisis Thorpe. Hasil penelitian ini menunjukkan bahwa percampuran yang kuat terjadi di area sekitar Pulau Sangihe-Talaud dengan nilai difusivitas vertikal . Bahkan pada area yang jauh dari pusat pembangkitan ditemukan difusivitas vertikal , hasil disipasi propagasi pasang surut internal. Berdasarkan hasil pengamatan menunjukan bahwa rata-rata tingkat energi kinetik disipasi turbulen eddy  Laut Sulawesi pada semua lapisan adalah . Nilai  di lapisan termoklin paling besar  dibandingkan dengan lapisan permukaan tercampur dan lapisan dalam yang hampir homogen, peningkatan percampuran di daerah dekat ridge disebabkan makin mendekatnya kolom air dengan topografi dasar. Rata-rata nilai percampuran turbulen sebesar , fluktuasi nilai yang paling kuat terjadi di lapisan termoklin, yang berkisar yaitu antara  sampai  dengan rerata sekitar . Nilai percampuran turbulen ini lebih tinggi dibandingkan dengan pengukuran sebelumnya di beberapa perairan Indonesia. Hal ini diduga karena adanya energi pasang surut internal yang kuat serta interaksinya dengan topografi yang ada di Laut Sulawesi.

scholarly journals Observational estimates of turbulent mixing in the southeast Indian Ocean

2021 ◽  
Author(s):  
Ajitha Cyriac ◽  
Helen E. Phillips ◽  
Nathaniel L. Bindoff ◽  
Huabin Mao ◽  
Ming Feng
Keyword(s):  
Indian Ocean ◽  
Turbulent Mixing ◽  
Large Scale ◽  
Bottom Topography ◽  
Intermediate Water ◽  
Depth Range ◽  
Mean Flow ◽  
Mode Water ◽  
South Indian ◽  
Spatio Temporal

AbstractThis study investigates the spatio-temporal variability of turbulent mixing in the eastern South Indian Ocean using a collection of data from EM-APEX profiling floats, shipboard CTD and microstructure profilers. The floats collected 1566 profiles of temperature, salinity and horizontal velocity data down to 1200 m over a period of about four months. A fine-scale parameterization is applied to the float and CTD data to estimate turbulent mixing. Elevated mixing is observed in the upper ocean, over bottom topography and in mesoscale eddies. Mixing is enhanced in the anticyclonic eddies due to trapped near-inertial waves within the eddy. We found that cyclonic eddies contribute to turbulent mixing in the depth range of 500 – 1000 m, which is associated with downward propagating internal waves. The mean diapycnal diffusivity over 250 – 500 m depth is O(10−6) m2 s−1 and it increases to O(10−5) m2 s−1 in 500 – 1000 m in cyclonic eddies. The turbulent mixing in this region has implications for watermass transformation and large-scale circulation. Higher diffusivity (O(10−5) m2 s−1) is observed in the Antarctic Intermediate Water (AAIW) layer in cyclonic eddies whereas weak diffusivity is observed in the Subantarctic Mode Water (SAMW) layer (O(10−6) m2 s−1). Counter-intuitively, then, the SAMW watermass properties are strongly affected in cyclonic eddies whereas the AAIW layer is less affected. Comparatively high diffusivity at the location of the South Indian Countercurrent (SICC) jets suggests there are wave-mean flow interactions in addition to the wave-eddy interactions that warrant further investigation.

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