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

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.

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

ILMU KELAUTAN Indonesian Journal of Marine Sciences ◽

10.14710/ik.ijms.19.1.43-54 ◽

2014 ◽

Vol 19 (1) ◽

pp. 43 ◽

Cited By ~ 1

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

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

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v6i2.9027 ◽

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

ABSTRACT Measurement of ocean physical parameters using the CTD was conducted by deep water expedition INDEX-SATAL 2010 (Indonesian Expedition Sangihe-Talaud) in July-August 2010. The aim of this study was to determine the characteristics of water masses around the Sangihe Talaud Water where there was an entry passage of Indonesian throughflow (ITF) at the west pathway that passed through the primary pathway i.e., the Sulawesi 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. Keywords: Index-Satal 2010, Northern Pacific Water Masses, Southern Pacific Water Masses, Sangihe Talaud

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Spatial distribution of turbulent diapycnal mixing along the Mindanao current inferred from rapid-sampling Argo floats

Journal of Oceanography ◽

10.1007/s10872-021-00624-3 ◽

2022 ◽

Author(s):

Ying He ◽

Jianing Wang ◽

Fan Wang ◽

Toshiyuki Hibiya

Keyword(s):

Turbulent Mixing ◽

North Pacific ◽

Water Mass ◽

Strong Mixing ◽

Western Boundary ◽

Diapycnal Mixing ◽

The North ◽

Rapid Sampling ◽

Mindanao Current ◽

The North Pacific

AbstractThe Mindanao Current (MC) bridges the North Pacific low-latitude western boundary current system region and the Indonesian Seas by supplying the North Pacific waters to the Indonesian Throughflow. Although the previous study speculated that the diapycnal mixing along the MC might be strong on the basis of the water mass analysis of the gridded climatologic dataset, the real spatial distribution of diapycnal mixing along the MC has remained to be clarified. We tackle this question here by applying a finescale parameterization to temperature and salinity profiles obtained using two rapid-sampling profiling Argo floats that drifted along the MC. The western boundary (WB) region close to the Mindanao Islands and the Sangihe Strait are the two mixing hotspots along the MC, with energy dissipation rate ε and diapycnal diffusivity Kρ enhanced up to ~ 10–6 W kg−1 and ~ 10–3 m2 s−1, respectively. Except for the above two mixing hotspots, the turbulent mixing along the MC is mostly weak, with ε and Kρ to be 10–11–10–9 W kg−1 and 10–6–10–5 m2 s−1, respectively. Strong mixing in the Sangihe Strait can be basically attributed to the existence of internal tides, whereas strong mixing in the WB region suggests the existence of internal lee waves. We also find that water mass transformation along the MC mainly occurs in the Sangihe Strait where the water masses are subjected to strong turbulent mixing during a long residence time.

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The Bacterial Community in the Western Region of North Pacific Intermediate Water

Microbiology Resource Announcements ◽

10.1128/mra.00757-19 ◽

2019 ◽

Vol 8 (34) ◽

Author(s):

Maki Teramoto ◽

Ayumi Komatsu ◽

Kouhei Ohnishi

Keyword(s):

Bacterial Community ◽

North Pacific ◽

Water Mass ◽

Western Region ◽

Intermediate Water ◽

North Pacific Intermediate Water ◽

Bacterial Composition ◽

The Western Region

The bacterial composition in North Pacific Intermediate Water (NPIW) was investigated in three different years and compared with that in other seawaters around Japan. The results indicated that bacterial composition was surprisingly stable at the same point in a mesopelagic water mass throughout the years and supported previous physicochemical observations that NPIW is distributed to Kumejima, Japan.

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Stratifikasi Massa Air di Teluk Lasolo, Sulawesi Tenggara

Oseanologi dan Limnologi di Indonesia ◽

10.14203/oldi.2016.v1i2.54 ◽

2016 ◽

Vol 1 (2) ◽

pp. 17

Author(s):

Dewi Surinati ◽

Edi Kusmanto

Keyword(s):

North Pacific ◽

Water Mass ◽

Acoustic Doppler Current Profiler ◽

Current Data ◽

Water Masses ◽

Intermediate Water ◽

North Pacific Intermediate Water ◽

Conservation Area ◽

Current Profiler ◽

Salinity Data

Stratification of Water Mass in Lasolo Bay, Southeast Sulawesi. As a nature conservation area, Lasolo Bay should be supported by data and information of waters oceanographic. Research for stratification of water masses in Lasolo Bay was conducted. from 10 to 19 July 2011. Temperature and salinity data were obtained using CTD SBE 911 Plus preinstalled on Research Vessel Baruna Jaya VIII at intervals of 24 data per second. Current data were obtained using Vessel Mounted Acoustic Doppler Current Profiler (VMADCP) with an interval of two seconds. The results show that there are differences in the speed and direction of currents in the water column that lead to stratification of water masses. Currents that drove the water mass of Banda Sea into Lasolo Bay was caused by southeasterly winds with an average speed of 4.1 m/s. At depths of 0–50 m and 100–200 m the current dominance occurs to the northwest, while at depths of 50–100 m and 200–350 m it occurs to the south. The water mass with a salinity of 32.1–34.0 PSU and temperature 26–28°C occupied the surface layer (0–50 m). The water mass with a salinity of 34.4–34.5 PSU identified as the water mass of North Pacific Intermediate Water (NPIW) occupied two depths, i.e. 50–100 m and 200–350 m with different range of temperatures. The water mass with maximum salinity (34.5–34.6 PSU), identified as the water mass of North Pacific Subtropical Water (NPSW) also occupied two depths i.e. 100–200 m and 350 m until near the bottom with different range of temperatures

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Indirect estimation of turbulent mixing in western route of Indonesian throughflow

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/944/1/012059 ◽

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.

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Observational estimates of turbulent mixing in the southeast Indian Ocean

Journal of Physical Oceanography ◽

10.1175/jpo-d-20-0036.1 ◽

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

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v6i2.9027 ◽

2015 ◽

Vol 6 (2) ◽

Author(s):

Ivonne M Radjawane ◽

Paundra P Hadipoetranto

Keyword(s):

North Pacific ◽

Water Mass ◽

Sea Water ◽

South Pacific ◽

New Guinea ◽

Water Masses ◽

Physical Parameters ◽

Coastal Current ◽

Indonesian Throughflow ◽

Pacific Water

ABSTRACT Measurement of ocean physical parameters using the CTD was conducted by deep water expedition INDEX-SATAL 2010 (Indonesian Expedition Sangihe-Talaud) in July-August 2010. The aim of this study was to determine the characteristics of water masses around the Sangihe Talaud Water where there was an entry passage of Indonesian throughflow (ITF) at the west pathway that passed through the primary pathway i.e., the Sulawesi 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. Keywords: Index-Satal 2010, Northern Pacific Water Masses, Southern Pacific Water Masses, Sangihe Talaud

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Tracing Water Mass Mixing From the Equatorial to the North Pacific Ocean With Dissolved Neodymium Isotopes and Concentrations

Frontiers in Marine Science ◽

10.3389/fmars.2020.603761 ◽

2021 ◽

Vol 7 ◽

Author(s):

Michael Fuhr ◽

Georgi Laukert ◽

Yang Yu ◽

Dirk Nürnberg ◽

Martin Frank

Keyword(s):

Pacific Ocean ◽

Deep Water ◽

Surface Waters ◽

North Pacific ◽

Water Mass ◽

North Pacific Ocean ◽

Water Masses ◽

Intermediate Water ◽

Nd Isotope ◽

Geochemical Tracers

The sluggish water mass transport in the deeper North Pacific Ocean complicates the assessment of formation, spreading and mixing of surface, intermediate and deep-water masses based on standard hydrographic parameters alone. Geochemical tracers sensitive to water mass provenance and mixing allow to better characterize the origin and fate of the prevailing water masses. Here, we present dissolved neodymium (Nd) isotope compositions (εNd) and concentrations ([Nd]) obtained along a longitudinal transect at ∼180°E from ∼7°S to ∼50°N. The strongest contrast in Nd isotope signatures is observed in equatorial regions between surface waters (εNd ∼0 at 4.5°N) and Lower Circumpolar Deep Water (LCDW) prevailing at 4500 m depth (εNd = −6.7 at 7.2°N). The Nd isotope compositions of equatorial surface and subsurface waters are strongly influenced by regional inputs from the volcanic rocks surrounding the Pacific, which facilitates the identification of the source regions of these waters and seasonal changes in their advection along the equator. Highly radiogenic weathering inputs from Papua-New-Guinea control the εNd signature of the equatorial surface waters and strongly alter the εNd signal of Antarctic Intermediate Water (AAIW) by sea water-particle interactions leading to an εNd shift from −5.3 to −1.7 and an increase in [Nd] from 8.5 to 11.0 pmol/kg between 7°S and 15°N. Further north in the open North Pacific, mixing calculations based on εNd, [Nd] and salinity suggest that this modification of the AAIW composition has a strong impact on intermediate water εNd signatures of the entire region allowing for improved identification of the formation regions and pathways of North Pacific Intermediate Water (NPIW). The deep-water Nd isotope signatures indicate a southern Pacific origin and subsequent changes along its trajectory resulting from a combination of water mass mixing, vertical processes and Nd release from seafloor sediments, which precludes Nd isotopes as quantitative tracers of deep-water mass mixing. Moreover, comparison with previously reported data indicates that the Nd isotope signatures and concentrations below 100 m depth essentially remained stable over the past decades, which suggests constant impacts of water mass advection and mixing as well as of non-conservative vertical exchange and bottom release.

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SUBTROPICAL WATER MASSES IN HALMAHERA WATERS

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v2i2.7857 ◽

2010 ◽

Vol 2 (2) ◽

Cited By ~ 1

Author(s):

Hadikusumah Hadikusumah

Keyword(s):

North Pacific ◽

Water Mass ◽

South Pacific ◽

Water Masses ◽

Intermediate Water ◽

Average Depth ◽

North Pacific Intermediate Water ◽

Subtropical Water ◽

Salinity Water ◽

Temperature Depth

Research of water masses by using conductivity temperature depth (CTD), are conducted in the eastern path of the Indonesia Throughflow (ITF) in the Halmahera, Seram and Banda seas during March-April 2007 under the Expedition of Widya Nusantara (EWIN). The objective of this research is to see maximum salinity spread of South Pacific Subtropical Water (SPSW) water masses enter the eastern Indonesia Waters. The temperature and salinity profiles show the presence of the presence of SPSW have been very much confined to the Halmahera Sea only. Little of this water masses have been detected in the eastern Seram Sea, but none in Banda Sea. Early data of Arlindo Mixing (ARMIX) experiment in southeast monsoon 1993 indicated that this water masses SPSW may entered the southern most part of the Moluccas Sea. Type of South Pacific Subtropical Water (SPSW) water masses appears in the Halmahera Sea at an average depth of 200m and the dominant flows between Halmahera and Obi Islands (Moluccas Sea continues to the east). Type of South Pacific Intermediate Water (SPIW) water mass appeared on average Halmahera Sea at a depth of 750m and the dominant flows between Halmahera and Obi Islands (Moluccas Sea continues to the east). Type of North Pacific Subtropical Water (NPSW) water masses at an average depth of ~ 150m found in the northern part of Halmahera, the dominant flow to the Celebes Sea, Makassar Strait, Flores Sea and partly flows into Lombok Straits. Type of minimum salinity water mass of North Pacific Intermediate Water (NPIW) obtained at an average depth of ~ 400m dominant flow towards the Celebes Sea, Makassar Strait and Flores Sea.Keywords: maximum salinity, SPSW, Halmahera, Seram, and Banda Seas

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