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Vertical Profile of Banda Sea Temperature Related to El Niño Events in the East Pacific and Central Pacific Prasetyo, Budi; Pusparini, Nikita; Radjawane, Ivonne Milichristi
Oseanologi dan Limnologi di Indonesia Vol 4, No 1 (2019)
Publisher : Indonesian Institute of Sciences

Eastern Pacific (EP) and Central Pacific El Niño have different characteristics such as mechanism, evolution, impact to Sea Surface Temperature (SST), and rainfall. The character of two types of El Nino affect the temperature of the sea, on the near-surface as well as in deeper layer, in other regions including Banda Sea. This study is aimed to understand the response of Banda Sea vertical sea temperature profile to both El Niño types using sea temperature data from Simple Ocean Data Assimilation (SODA) v.2.2.4 from January 1950 until December 2010 (60 years), Oceanic Nino Index (ONI), and mixed layer depth (MLD) from SODA3. Eastern Pacific El Niño and CP El Niño cooled Banda Sea about -1.5°C and 0.9°C, respectively. The maximum cooling due to both El Niño occurred in the thermocline layer (at the depth of 90 to 120m). The maximum temperature decrease during EP El Niño occurred at the depth of 90 to 120 m, while during CP El Niño the maximum temperature decrease was at 140 to 160 m and 160 to 200m in western and eastern Banda Sea, respectively. The temperature of the near-surface layer responded rapidly to CP El Niño while in the deep layer the temperature responded more to EP El Niño. The Banda deep sea layer was cooling after both types of El Niño extinct while the temperature of near-surface layer was increasing when CP El Niño extinct

CORRELATION AND COHERENCE ANALYSIS OF SEA SURFACE TEMPERATURE (SST) DISTRIBUTED BY THE SURFACE WIND IN WEST SUMATERA WATERS Ulung Jantama Wisha; Rahaden Bagas Hatmaja; Ivonne Milichristi Radjawane; Try Al Tanto
Jurnal Meteorologi dan Geofisika Vol 19, No 2 (2018)
Publisher : Pusat Penelitian dan Pengembangan BMKG

West Sumatera Waters have a tremendous dynamic in ocean characteristics. It directly faces the Indian Ocean exactly located below the equator. Consequently, West Sumatera waters are influenced by the tropical climatic factors such as monsoons, climate variability, and the Indian Ocean Dipole (IOD), controlling sea surface temperature (SST) fluctuation in the Indian Ocean. This study aims to review the correlation and coherence of SST distributed by surface wind in the West Sumatera waters. Wavelet method (cross wavelet transforms and wavelet coherence) was used to analyze the correlation and coherency between SST and surface wind. The annual variation of SST for 365 days period is the strongest event throughout the year caused by either monsoon or the changes of wind speed in the surface. Otherwise, the strongest intra-seasonal SST variation of 35 - 60 days observed from December 2012 to March 2013. The highest surface wind speed occurs in the southern and western waters. During the positive dipole mode in October 2015, the surface wind speed is slightly high resulting in the SST declination. Nevertheless, during the negative dipole mode in July 2016, the condition is inversely proportional. The surface wind plays a role in the SST distribution of 35 - 60 days period (intra-seasonal variability). Besides, surface wind with 6 months period (semi-annual variability) influences the SST distribution, identified only in the southern waters and the Indian Ocean regions. These conditions predicted as the influence of monsoon. Sumatera Barat merupakan wilayah perairan yang stategis dimana secara langsung berhadapan dengan Samudera Hindia dan tepat berada pada dibawah Garis Katulistiwa. Oleh karena itu, Perairan Sumatera Barat dipengaruhi oleh faktor-faktor iklim tropis seperti monsun dan variabilitas iklim, sangat terkait dengan Indian Ocean Dipole (IOD) yang mengendalikan fluktuasi suhu permukaan laut (SPL) di Samudera Hindia. Tujuan dari penelitian ini adalah menelaah korelasi dan koherensi antara parameter SPL dan komponen kecepatan angin di perairan Sumatera Barat. Metode wavelet (cross wavelet transform dan wavelet coherence) digunakan untuk menganalisa korelasi dan koherensi dari kedua parameter yang diuji. Variasi tahunan dari SPL pada periode 365 hari merupakan kejadian terkuat sepanjang tahun yang disebabkan oleh monsun atau perubahan pengaruh angin dipermukaan. Sebaliknya, variasi musiman terkuat dari SPL pada periode 35-60 hari ditemukan terjadi pada bulan Desember 2012 hingga Maret 2013. Kecepatan angin tertinggi terjadi di perairan selatan dan barat. Selama dipole mode positif pada bulan Oktober 2015, kecepatan angin permukaan sedikit meningkat yang mengakibatkan penurunan suhu perairan. Namun, selama dipole mode negatif pada bulan Juli 2016, kondisinya berbanding terbalik. Angin permukaan memainkan peran pada peningkatan distribusi suhu permukaan laut pada periode 35-60 hari (variabilistas musiman). Selain itu, angin permukaan dengan periode 6 bulan (tengah tahunan) sangat mempengaruhi distribusi suhu yang teridentifikasi pada wilayah selatan dan Samudera Hindia. Kondisi tersebut diperkirakan sebagai pengaruh dari monsun.

Seasonal Monitoring of Ocean Parameter Over Green Mussel Cultivation area in West Part of Cirebon Seawater Mochamad Riam Badriana; Ashadi Arifin Nur; Arsy Ilham Hidayatullah; Abi Widyananto Prastyo; Lamona Imudyati Bernawis; Chungkyun Jeon; Ivonne Milichristi Radjawane; Hansan Park
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 28, No 1 (2023): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.28.1.69-80

West part of Cirebon in the past suffered an extraordinary event due to poisonous food found in green mussel. It is necessary to monitor current water quality over this region since this area still used for green mussel cultivation area. In-situ measurement and laboratory analysis were done to monitor the condition of seawater around Gunungjati as part of green mussel cultivation area in Cirebon regency. Several points had been measured through CTD Valeport Midas+ in prior to measure physical (temperature, salinity, pH, chlorophyll-a, turbidity) and chemical seawater (dissolved oxygen, Nitrate, Orthophosphate, Hg, Pb, Cd concentration) characteristics, meanwhile water sample had been brought to laboratory to be checked its heavy metal concentration. Additionally, past study and data related to green poison event in Cirebon was taken account into observation and analysis. Seasonal result show slightly different value though vertical distribution data where temperature (30.1°–32.3°C), salinity (26.9–32.0 psu), and pH (7.5–8.7) are high in December but lower in July, meanwhile, chlorophyll-a (0.2–20.9 mg.L-1), dissolved oxygen (0.2–7.8 mg.L-1), and turbidity (1.3–20.1 NTU) are increasing in October. Nitrate and orthophosphate concentration find in water sample is 0.097–0.537 mg.L-1 and <0.01–0.32 mg.L-1, respectively. Parameters of Cd (<0.001 mg.L-1), Hg (<0.00014 mg.L-1), and Pb (<0.001 mg.L-1) are still below the threshold. The condition of seawater of west part of Cirebon or at cultivation area is still in moderate condition based on the national standard. Although, turbidity and dissolved oxygen is still above the standard quality.

KARAKTERISTIK SUHU DAN SALINITAS VERTIKAL TERHADAP MASSA AIR SELAMA PERIODE IOD (+) , IOD (-) , MUSIM BARAT, DAN MUSIM TIMUR DI SELAT MENTAWAI Rezfiko Agdialta; Fajar Sidiq Ariwibaowo; Ivonne Milichristi Radjawane; Lamona Irmudyawati Bernawis
Maspari Journal : Marine Science Research Vol 15, No 1 (2023)
Publisher : UNIVERSITAS SRIWIJAYA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56064/maspari.v15i1.21080

Selat Mentawai merupakan bagian Perairan Barat Indonesia yang secara geografis dilalui fenomena antar tahunan Indian Ocean Dipole (IOD) dan perubahan monsun. Dampak yang ditimbulkan oleh fenomena tersebut terhadap karakteristik massa air, khususnya berkaitan dengan distribusi, stratifikasi dan proses percampuran massa air yang berasal dari Perairan Samudera Hindia menjadi fokus utama penelitian. Lokasi penelitian dilakukan di Selat Mentawai yang secara geografis terletak antara 2,3° – 3,3° Lintang Utara dan 100° – 101,5° Bujur Timur, dimana terbagi dalam 4 periode penelitian yaitu: IOD Positif (+), IOD Negatif (-), Monsun Timur dan Monsun Barat. Kajian dilakukan menggunakan data insitu dari instrumen Conductivity Temperature Depth (CTD) untuk mengukur parameter kedalaman, temperatur, dan salinitas. Analisis data CTD menggunakan diagram T-S yang menunjukan hubungan antara suhu dan salinitas di beberapa kedalaman. Selain itu data model arus yang bersumber dari marine.copernicus.eu digunakan untuk melihat distribusi arus laut secara horizontal. Pengolahan data dilakukan dengan memanfaatkan perangkat lunak Ocean Data View (ODV). Secara umum, hasil analisa diagram T-S menunjukan lapisan termoklin berada pada kedalaman antara 50 sampai dengan 150 meter. Dimana lapisan termoklin saat IOD (-) pada kedalaman (92 – 155 meter) dimana lebih dalam daripada IOD (+) pada kedalaman (77 – 130 meter). Lapisan termoklin saat monsun barat pada kedalaman (92,3 - 155,8 meter) lebih dalam daripada monsun timur pada kedalaman (55,7 – 109,7 meter). Arus laut Selat Mentawai dipengaruhi oleh perubahan IOD dan monsun, dimana saat IOD (-) arah arus dominan dari Barat Laut ke Tenggara dan sebaliknya saat IOD (+) arah arus dominan dari Tenggara ke Barat Laut. Sedangkan pada saat monsun barat arah arus dominan dari Barat Laut ke Tenggara. Sebaliknya saat monsun timur arah arus dominan dari Tenggara ke Barat laut. Karakteristik massa air di Upper Water (0 – 500 meter) wilayah Selat Mentawai terdiri dari Benggal Bay Water (BBW), Subtropical Low Water (SLW), South Indian Central Water (SICW), Indonesian Upper Water, dan Indian Equatorial Water. Sementara untuk wilayah Intermidiate Water massa air yang paling dominan berasal dari Red-Sea Persian Intermediate Water (RSPIW). Pada kondisi IOD +, IOD -, Monsun Barat, dan Monsun Timur tidak terdapatnya perbedaan karakteristik massa air.

CORRELATION AND COHERENCE ANALYSIS OF SEA SURFACE TEMPERATURE (SST) DISTRIBUTED BY THE SURFACE WIND IN WEST SUMATERA WATERS Ulung Jantama Wisha; Rahaden Bagas Hatmaja; Ivonne Milichristi Radjawane; Try Al Tanto
Jurnal Meteorologi dan Geofisika Vol. 19 No. 2 (2018)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v19i2.572

West Sumatera Waters have a tremendous dynamic in ocean characteristics. It directly faces the Indian Ocean exactly located below the equator. Consequently, West Sumatera waters are influenced by the tropical climatic factors such as monsoons, climate variability, and the Indian Ocean Dipole (IOD), controlling sea surface temperature (SST) fluctuation in the Indian Ocean. This study aims to review the correlation and coherence of SST distributed by surface wind in the West Sumatera waters. Wavelet method (cross wavelet transforms and wavelet coherence) was used to analyze the correlation and coherency between SST and surface wind. The annual variation of SST for 365 days period is the strongest event throughout the year caused by either monsoon or the changes of wind speed in the surface. Otherwise, the strongest intra-seasonal SST variation of 35 - 60 days observed from December 2012 to March 2013. The highest surface wind speed occurs in the southern and western waters. During the positive dipole mode in October 2015, the surface wind speed is slightly high resulting in the SST declination. Nevertheless, during the negative dipole mode in July 2016, the condition is inversely proportional. The surface wind plays a role in the SST distribution of 35 - 60 days period (intra-seasonal variability). Besides, surface wind with 6 months period (semi-annual variability) influences the SST distribution, identified only in the southern waters and the Indian Ocean regions. These conditions predicted as the influence of monsoon. Sumatera Barat merupakan wilayah perairan yang stategis dimana secara langsung berhadapan dengan Samudera Hindia dan tepat berada pada dibawah Garis Katulistiwa. Oleh karena itu, Perairan Sumatera Barat dipengaruhi oleh faktor-faktor iklim tropis seperti monsun dan variabilitas iklim, sangat terkait dengan Indian Ocean Dipole (IOD) yang mengendalikan fluktuasi suhu permukaan laut (SPL) di Samudera Hindia. Tujuan dari penelitian ini adalah menelaah korelasi dan koherensi antara parameter SPL dan komponen kecepatan angin di perairan Sumatera Barat. Metode wavelet (cross wavelet transform dan wavelet coherence) digunakan untuk menganalisa korelasi dan koherensi dari kedua parameter yang diuji. Variasi tahunan dari SPL pada periode 365 hari merupakan kejadian terkuat sepanjang tahun yang disebabkan oleh monsun atau perubahan pengaruh angin dipermukaan. Sebaliknya, variasi musiman terkuat dari SPL pada periode 35-60 hari ditemukan terjadi pada bulan Desember 2012 hingga Maret 2013. Kecepatan angin tertinggi terjadi di perairan selatan dan barat. Selama dipole mode positif pada bulan Oktober 2015, kecepatan angin permukaan sedikit meningkat yang mengakibatkan penurunan suhu perairan. Namun, selama dipole mode negatif pada bulan Juli 2016, kondisinya berbanding terbalik. Angin permukaan memainkan peran pada peningkatan distribusi suhu permukaan laut pada periode 35-60 hari (variabilistas musiman). Selain itu, angin permukaan dengan periode 6 bulan (tengah tahunan) sangat mempengaruhi distribusi suhu yang teridentifikasi pada wilayah selatan dan Samudera Hindia. Kondisi tersebut diperkirakan sebagai pengaruh dari monsun.

The One-Dimensional (1D) Numerical Model: An Application to Oxygen Diffusion in Mitochondria Cell Gandhi Napitupulu; Achmad Nagi; Mutiara Rachmat Putri; Ivonne Milichristi Radjawane
ComTech: Computer, Mathematics and Engineering Applications Vol. 14 No. 2 (2023): ComTech
Publisher : Bina Nusantara University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21512/comtech.v14i2.9705

The first model of oxygen transport was formulated by August Krogh. However, the investigations conducted have yet to yield a complete analytical model and a widely applicable solution for One-Dimensional (1D) network construction. The research sought to provide numerical and analytical solutions for the oxygen transfer model in mitochondrial cells to enable researchers to estimate the molecular dynamics and diffusion characteristics in mitochondrial cells. The oxygen diffusion process in mitochondria was modeled with ID numerical models. The numerical models used to solve the equations were explicit and implicit. The explicit model consisted of Forward Time Center Space (FTCS) and DuFort-Frankel. Meanwhile, the implicit model had Crank-Nicholson and Laasonen. The numerical solutions of the explicit and implicit were divided into four scenarios with a variation of Δt and compared with the analytical solutions. The results show that the Laasonen method is the best in describing the diffusion process. The best scenario with the lowest slope value and small Root Mean Square Error (RMSE) value is scenario 2 (Δt = 3,33E-4 s and Δx = 2,00E-5 cm). The numerical model and analytical solution show that the time required to reach a steady state is 0,7 s. It indicates oxygen exchange in two sides of the mitochondrial cell after 0,7 s.

Pemetaan Zona Potensial Penangkapan Ikan Tongkol di Perairan Teluk Banten Achmad Nagi; Gandhi Napitupulu; Ivonne Milichristi Radjawane; Susanna Nurdjaman; Dedi Supriadi; Dewi Nurhayati
Buletin Oseanografi Marina Vol 12, No 3 (2023): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v12i3.50374

Ikan Tongkol (Euthynnus affinis) adalah komoditas di perairan Teluk Banten yang memiliki nilai produksi tinggi. Potensi ini bisa dimanfaatkan secara maksimal melalui pengetahuan tentang Zona Potensial Penangkapan Ikan (ZPPI). Penelitian ini bertujuan untuk menganalisis hubungan antara parameter oseanografi (suhu permukaan laut (SPL) dan klorofil-a) dan hasil tangkapan Ikan Tongkol, serta membuat pemetaan ZPPI Ikan Tongkol pada tahun 2014-2019. Prediksi ZPPI dilakukan melalui pendekatan parameter oseanografi berdasarkan citra satelit dan data hasil tangkapan Ikan Tongkol. Rata-rata tertinggi produksi Ikan Tongkol tahun 2014-2019 di Teluk Banten diperoleh selama musim peralihan I dengan SPL 29,92C – 30,98C dan konsentrasi klorofil-a 0,99 – 1,13 mg/m³. Analisis pengaruh SPL dan klorofil-a pada tangkapan dilakukan dengan regresi berganda. Pengaruh SPL dan klorofil-a terhadap hasil tangkapan dinilai cukup kuat berdasarkan dari koefisien korelasi () 0,743 dan koefisien determinasi () sebesar 0,551. Nilai dapat memberikan penjelasan bahwa SPL dan klorofil-a mempengaruhi hasil tangkapan sebesar 55,1%. Melalui Analisis Wavelet diperoleh persebaran klorofil-a dominan dipengaruhi faktor monsun sedangkan pengaruh IOD (Indian Ocean Dipole) dan ENSO (El Niño–Southern Oscillation) lemah, sehingga pemetaan ZPPI disusun berdasarkan empat musim. ZPPI yang memiliki potensi lokasi terbanyak diperoleh pada musim barat sejumlah 13 titik. Selanjutnya, berkurang pada musim peralihan I sebanyak 10 titik, musim peralihan II sebanyak 6 titik, dan musim timur sebanyak 4 titik. Mackarel Tuna (Euthynnus affinis) is a commodity in Banten Bay waters that has high production value. This potential can be maximally utilized through knowledge of the Potential Fishing Zone (). This study aims to analyze the relationship between oceanographic parameters (sea surface temperature (SST) and chlorophyll-a) and the catch of Mackarel Tuna, and create PFZ mapping of Mackarel Tuna in 2014-2019. The prediction of PFZ is done through the approach of oceanographic parameters based on satellite imagery and catch data. The highest average production of Mackarel Tuna in 2014-2019 in Banten Bay was obtained during transitional season I with a SST of 29.92°C - 30.98°C and a chlorophyll-a concentration of 0.99 - 1.13 mg/m³. Analysis of the effect of SST and chlorophyll-a on catch was done with multiple regression. The influence of SST and chlorophyll-a on catch was considered quite strong based on the correlation coefficient () of 0.743 and the coefficient of determination () of 0.551. The value can provide an explanation that SST and chlorophyll-a affect the catch by 55.1%. Through Wavelet Analysis, it is obtained that the distribution of chlorophyll-a is dominantly influenced by monsoon factors while the influence of IOD (Indian Ocean Dipole) and ENSO (El Niño-Southern Oscillation) is weak, so that mapping is organized based on four seasons. The that has the most potential locations is obtained in the west season with 13 points. Furthermore, it decreases in the first transition season with 10 points, the second transition season with 6 points, and the eastern season with 4 points.

Seasonal Variability of Sea Surface Chlorophyll-a at West Borneo Island Radjawane, Ivonne Milichristi; Saleh, Ejria; Napitupulu, Gandhi; Abdillah, Muhammad Rais; Hassan, Mohd Azamuddin Mohd
Indonesian Journal of Geography Vol 56, No 1 (2024): Indonesian Journal of Geography
Publisher : Faculty of Geography, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijg.87713

The optimization of marine fisheries activities can be achieved through an understanding of the timing of fishing, access to good information, and knowledge of oceanographic conditions. These conditions often lead to significant nutrient enrichment in the surface layer of the ocean, which in turn increases the sea surface chlorophyll-a (SSC). In the context of the west Borneo Island region, seasonal variability in SSC plays a crucial role in determining potential fishing grounds. The objectives of this study are examining the seasonal variability of SSC, identifying upwelling and downwelling processes through analysis of sea surface wind (SSW), and determining the climatological distribution of Sea Surface Temperature (SST) and sea surface height (SSH) within the water off Labuan Island, Malaysian Borneo, and the Karimata Strait, West Kalimantan, Indonesia. Remote sensing data spanning from 2007 to 2021 were analyzed, encompassing SSC, SST, SSH anomalies, SSW, wind stress curl, and Ekman pumping. Additionally, rainfall and river discharge were examined as supplementary indicators of these oceanographic processes. The findings indicate that SSW plays a pivotal role in driving upwelling and downwelling processes, which in turn influence SSC variability. In Labuan waters, upwelling occurs primarily from November to February, while downwelling predominates from June to September. In contrast, in the Karimata Strait, upwelling is identified from July to September, with downwelling prevalent between March and May. Upwelling events in both regions are characterized by increasing SSC, accompanied by decreasing SST and SSH, while the opposite trends are observed during downwelling events. The peak of rainfall and river discharge in December is noted to potentially enhance SSC variability in the Karimata Strait compared to Labuan Island waters.

PENGELOLAAN DAN PEMANFAATAN KAWASAN PESISIR PULAU MIANGAS SEBAGAI PULAU KECIL TERLUAR INDONESIA Nagi, Achmad; Jamaluddin, Jamaluddin; Napitupulu, Gandhi; Nurdjaman, Susanna; Setyobudiandi, Isdradjad; Radjawane, Ivonne Milichristi
Jurnal Kebijakan Perikanan Indonesia Vol 15, No 1 (2023): (Mei) 2023
Publisher : Pusat Riset Perikanan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15578/jkpi.15.1.2023.%p

Pulau Miangas merupakan salah satu pulau terluar yang berbatasan dengan negara Filipina dan terletak di wilayah administratif Kabupaten Kepulauan Talaud di Provinsi Sulawesi Utara. Sumber daya alam yang ada memiliki potensi yang besar untuk pemanfaatan wilayah pesisir dan laut yang dimilikinya. Tujuan dari penelitian ini adalah menganalisis potensi, kelayakan dan prioritas komersial untuk pemanfaatan sumber daya pesisir Pulau Miangas. Survei dengan pengamatan secara langsung dan metode wawancara digunakan untuk mengumpulkan data dan informasi. sedangkan metode analisis sistem informasi geografis (SIG) digunakan untuk mengevaluasi kelayakan penggunaan lahan di wilayah pesisir. Melalui empat tahapan analisis yang meliputi penyusunan peta wilayah, matriks cakupan per kategori, pemberian bobot dan scoring, serta analisis spasial. Hasil analisis kesesuaian lahan dengan menggunakan SIG menunjukkan bahwa kawasan pesisir Pulau Miangas memiliki potensi untuk berbagai program pembangunan terkait pengelolaan dan pemanfaatan pesisir, seperti kawasan pemukiman, kawasan budidaya rumput laut, kawasan penangkapan ikan, kawasan budidaya keramba jaring apung, budidaya mutiara dan konservasi terumbu karang.Miangas Island is one of the outermost islands bordering the Philippines and is located in the administrative area of the Talaud Islands Regency in North Sulawesi Province. The existing natural resources have great potential for the utilization of coastal and marine areas. The purpose of this study was to analyze the potential, feasibility and commercial priorities for the utilization of coastal resources of Miangas Island. Direct observation surveys and interview methods were used to collect data and information, while geographic information system (GIS) analysis methods were used to evaluate the feasibility of land use in coastal areas. Through four stages of analysis that include the preparation of area maps, coverage matrix per category, weighting and scoring, and spatial analysis. The results of the land suitability analysis using GIS show that the coastal area of Miangas Island has the potential for various development programs related to coastal management and utilization, such as residential areas, seaweed cultivation areas, fishing areas, floating net cage cultivation areas, pearl cultivation and coral reef conservation.

Pengaruh Sirkulasi Arus Geostropik dan Ageostropik Terhadap Upwelling di Perairan Selatan Jawa Radjawane, Ivonne Milichristi; Yusarita, Alvi; Kuswardani, Anastasia Rita Tisiana Dwi; Napitupulu, Gandhi
Buletin Oseanografi Marina Vol 13, No 3 (2024): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v13i3.62368

Perairan selatan Jawa merupakan lokasi dengan fenomena upwelling yang signifikan. Penelitian bertujuan untuk memahami kecepatan dan pola arus geostropik serta ageostropik orde dua musiman dari permukaan hingga kedalaman 600 m. Nilai Ekman pumping velocity (EPV) yang dibangkitkan oleh angin menunjukkan upwelling mulai bulan Juni, mencapai puncaknya dari Juli hingga September, dan menurun mulai Oktober, hampir menghilang pada November. Nilai EPV antara perairan Jawa Barat dan Timur menunjukkan tingkat upwelling yang lebih tinggi di sebelah barat. Data CTD menegaskan bahwa upwelling terjadi selama musim Timur (Juni-Agustus), ditandai dengan penurunan suhu air, dangkalnya termoklin, dan peningkatan salinitas terhadap kedalaman. Pada musim barat (Desember-Februari), arus geostropik cenderung ke timur di sepanjang pantai Jawa Barat karena arus selatan Jawa (ASJ), sementara di selatan Jawa Tengah dan Jawa Timur, arah arus ke barat disebabkan oleh arus lintas Indonesia (Arlindo) dan arus ekuator selatan (AES). Pada musim timur, ASJ melemah, dan arah arus geostropik berubah ke barat, memperkuat ASJ dan Arlindo. Sirkulasi Sekunder Ageostropik, diperkirakan melalui metode C-Vektor, memainkan peran dalam pergerakan massa air vertikal, meningkatkan intensitas upwelling di perairan selatan Jawa. Wilayah sekitar Jawa Timur memiliki komponen C-Vektor positif yang berdampak pada peningkatan intensitas upwelling di daerah tersebut. The southern waters of Java are a location with significant upwelling phenomena. The study aimed to understand the velocity and pattern of seasonal second-order geostropic and ageostropic currents from the surface to 600 m depth. Wind-generated Ekman pumping velocity (EPV) values show upwelling starting in June, peaking from July to September, and decreasing from October, almost disappearing in November.. The EPV values between western and eastern Java waters show higher levels of upwelling in the west. CTD data confirms that upwelling occurs during the East season (June-August), characterized by decreasing water temperature, shallow thermocline, and increasing salinity with depth. In the West season (December-February), geostropic currents tend to be eastward along the West Java coast due to the South Java Current (SJC), while south of Central Java and East Java, the current direction is westward due to the Indonesian Throughflow ( ITF ) and the South Equatorial Current (SEC). In the eastern season, the SJC weakens, and the direction of the geostropic current changes to the west, strengthening the SJC and ITF. The Ageostropic Secondary Circulation, estimated through the C-Vector method, plays a role in the vertical movement of water masses, increasing the intensity of upwelling in the waters south of Java. The region around East Java has a positive C-Vector component which has an impact on increasing the intensity of upwelling in that area.

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