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Kajian Daerah Rawan Bencana Gelombang Badai Pasang (Storm Tide) di Kawasan Pesisir Selatan Jawa, Bali, dan Nusa Tenggara Barat Ningsih, Nining Sari; Hadi, Safwan; Harto, Agung B.; Utami, M. D.; Rudiawan, Amanda P
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 15, No 4 (2010): Jurnal Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

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Abstract

Gelombang badai pasang (storm tide) yang dibangkitkan pasang surut dan siklon tropis di Samudera Hindia sering menerjang kawasan pesisir selatan Jawa, Bali, dan Nusa Tenggara Barat (NTB). Pada penelitian ini, model hidrodinamika dua dimensi (2D) horisontal Mike 21 digunakan untuk mensimulasikan tinggi gelombang, run-up, dan genangan di sepanjang kawasan pesisir selatan Jawa, Bali, dan NTB yang ditimbulkan oleh penjalaran gelombang pasang surut dan badai yang dibangkitkan oleh badai Jacob (2-12 Maret 2007) dan George (3-9 Maret 2007) di perairan pantai barat laut Australia. Penjalaran gelombang badai pasang disimulasikan dengan menggunakan data elevasi pasang surut di daerah batas terbuka model, angin, tekanan udara, dan lintasan badai. Data elevasi pasang surut diperoleh dari TMD (tide model driver), sedangkan data angin dan tekanan udara diperoleh dari NCEP (National Centers for Environmental Prediction). Data sea level anomaly (SLA) mingguan dari TOPEX Poseidon digunakan untuk memverifikasi tinggi gelombang badai (surge) yang dihasilkan model. Gelombang badai (surge) tertinggi di kawasan pesisir selatan Jawa, Bali, dan NTB, masing-masing  terjadi di Nusa Kambangan (Jawa; 19,0 cm), Tuban (Bali; 14,7 cm), Teluk Gumbang (Lombok; 12,2 cm), dan Tanjung Labulawah (Sumbawa; 12,5 cm). Jarak genangan maksimum gelombang badai pasang serta tinggi run-up yang menyertainya (H) terjadi di Teluk Penanjung (Jawa; R max = 835,2 m, H= 0,73 m), Tuban (Bali; R max = 623,5 m, H= 1,02 m), Tanjung Ringgit (Lombok; R max = 1112,3 m, H= 1,03 m) dan Teluk Cempi (Sumbawa; R max = 4136,5 m, H= 1,10 m)Kata kunci : gelombang badai, gelombang badai pasang, genangan, run-up, model hidrodinamika Storm surges generated by tropical cyclone in the Indian Ocean have often attacked southern coasts of Java, Bali, and Nusa Tenggara Barat (NTB). In this study, A two-dimensional (2D) hydrodynamic model of Mike 21 has been applied to simulate wave height, run-up, and inundation along the southern coasts of Java, Bali, and NTB, generated by tides and the Cyclone Jacob during 2-12 March 2007 and by the Cyclone George during 3-9 March 2007 in northwestern coastal waters of Australia. The storm tide event was simulated by imposing tidal elevations at the open boundaries, winds, air pressure, and storm tracks. Tidal elevation data were derived from TMD (tide model driver), while wind and air pressure data were obtained from NCEP (National Centers for Environmental Prediction). The weekly TOPEX Poseidon Sea Level Anomaly (SLA) was used to validate the model results of surge height. Highest surges along the southern coasts of Java, Bali, and NTB existed at Nusa Kambangan (Jawa; 19.0 cm), Tuban (Bali; 14.7 cm), Teluk Gumbang (Lombok; 12.2 cm), and Tanjung Labulawah (Sumbawa; 12.5 cm). Maximum distances of storm tide flooding (Rmax) and their associated run-up heights (H) occured at Teluk Penanjung (Jawa; R max = 835.2 m, H = 0.73 m), Tuban (Bali; Rmax = 623. m, H = 1.02 m), Tanjung Ringgit (Lombok; R max = 1112.3 m, H = 1.03 m), and Teluk Cempi (Sumbawa; Rmax = 4136.5 m, H= 1.0 m). Key words : storm surges, storm tide, inundation, run-up, hydrodynamic model.
Variabilitas Suhu dan Klorofil-a di Daerah Upwelling pada Variasi Kejadian ENSO dan IOD di Perairan Selatan Jawa sampai Timor Kunarso, Kunarso; Hadi, Safwan; Ningsih, Nining Sari; Baskoro, Mulyono S.
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 16, No 3 (2011): Jurnal Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

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Abstract

Informasi mengenai variabilitas spasial suhu dan klorofil-a permukaan laut memiliki peran penting sebagai sarana pendugaan daerah potensi ikan tuna. Penelitian ini bertujuan untuk mengkaji dan menggambarkan variabilitas suhu dan klorofil-a permukaan laut baik secara spasial maupun temporal di daerah upwelling pada variasi kejadian El Nino Southern Oscilation (ENSO) dan Indian Oscillation Dipole Mode (IOD) di perairan Selatan Jawa hingga Timor. Variabilitas suhu dan klorofil-a permukaan laut dikaji berdasarkan data-data MODIS (Moderate-Resolution Imaging Spektroradiometer) bulanan Level 3 dari satelit Aqua dan Terra. Nilai suhu dan klorofil-a permukaan laut bervariasi menurut waktu (bulan), wilayah (provinsi) dan variasi antar tahunan iklim global (El Niño-IOD(-), El Niño-IOD(+), La Niña-IOD(-) dan  La Niña-IOD(+). Secara umum kisaran suhu permukaan laut (SPL)  di  daerah  upwelling  pada  variasi  ENSO  dan  IOD  berkisar 26,18 -28,35°C  dengan  rerata 27,04±0,93°C. Kisaran klorofil-a sebesar 0,3-0,95 mg/M³ dengan rerata 0,69±0,28mg/M³. Mulai bulan Juni umumnya nilai suhu permukaan laut (SPL) semakin turun dan klorofil-a semakin meningkat hingga mencapai puncak bulan Agustus atau September, kemudian berangsur normal kembali. Nilai suhu permukaan laut terendah  ditemukan berkembang dari timur (Bali) pada bulan Juni bergerak ke barat hingga Jawa Barat di bulan Oktober. Nilai klorofil-a tinggi berkembang sesuai dengan perkembangan suhu terendah, namun nilai klorofil-a tertinggi umumnya bergerak tidak sesuai dengan perkembangan SPL terendah. Klorofil-a tertinggi umumnya terjadi di perairan selatan Provinsi Bali. Jauh dekatnya pergerakan SPL terendah dan klorofil-a tinggi tampak dipengaruhi nilai IOD-nya, semakin besar nilai IOD maka semakin jauh gerakannya ke barat.Kata Kunci : Variabilitas, suhu, klorofil-a, upwelling, perairan selatan Jawa The information of spatial variabilities of sea surface temperature and chlorophyll-a are important for predicting potential fishing ground of tuna. The aims of the reseach are to describe and study the spatial and temporal variabilities of sea surface temperature and chlorophyll-a at  upwelling area  during the variabilities of El Nino Southern Oscilation (ENSO) and Indian Oscillation Dipole Mode (IOD) event  at southern waters of Jawa until Timor Island. They were studied based on monthly MODIS (Moderate-Resolution Imaging Spektroradiometer) data  Level 3 from Aqua and Terra satelite. The values of sea surface temperature and chlorophyll-a are variable in the times (month), areas (province) and annually global climate (El Niño-IOD(-), El Niño-IOD(+), La Niña-IOD(-) dan  La Niña-IOD(+). Commonly range of the seawater surface temperature (SST) at upwelling area on the variabilities of ENSO and IOD are about 26.18-28.35°C with average 27.04±0,93°C, whereas average of chlorophyll-a are about 0.3-0.95 mg/m³ with average 0.69±0,28mg/M³. From June, sea surface temperature starts to decrease but clhorophyl-a is increasing and back to  normal after reaching peak in August or September. The lowest sea surface temperature was found developing from east (Bali) in June and then moving to west until southern west Java  in  October. The development of high chlorophyll-a values are suitable with that of low sea surface temperature. However the development of highest chlorophyll-a generally move inconsistent with that of lowest sea surface temperature. The highest chlorophyll-a generally happen at the southern of Bali Province. The distance movement of the low sea surface temperature and high chlorophyll-a distributions are affected by IOD value, the higher IOD value the further they move to the west. Key words: Variability, temperature, khlorophyll-a, upwelling, southern waters of Jawa
Studi Awal Pemodelan Medan Gelombang di Laut Jawa dan Karakteristik Spektrum Energi Gelombang di Teluk Jakarta Hadi, Safwan; Ningsih, Nining Sari; Pujiana, Kandaga
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 10, No 3 (2005): Jurnal Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

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Abstract

Informasi tentang karakteristik gelombang suatu perairan merupakan hal yang penting untuk diketahui guna melakukan berbagai aktifitas di laut seperti penangkapan ikan, pelayaran, rekayasa pantai dan lepas pantai.Pengukuran lapangan dalam waktu yang panjang dapat memberikan informasi ini tetapi memerlukan biaya yang sangat besar. Dengan semakin meningkatnya kemampuan komputer, informasi ini dapat diperoleh melalui simulasi model numerik. Dalam studi ini simulasi model numerik dilakukan untuk mendapatkan informasi tentang karakteristik gelombang di laut Jawa dan spektrum energi gelombang di Teluk Jakarta. Model numerik yang digunakan adalah model gelombang generasi ke – 3, WAM Model Cycle 4. Penerapan model dilakukanpada musim barat dan musim timur untuk melihat pengaruh arus laut pada karakteristik gelombang di Laut Jawa dan spektrum energi gelombang di Teluk Jakarta. Hasil simulasi model di Laut Jawa menunjukkan bahwa pada musim barat tinggi gelombang signifikan dan perioda puncak secara berturut-turut berkisar antara 0,44 – 1,83 m dan 2 – 5 detik sementara pada musim timur berkisar antara 0,35 – 1,06 m dan 2 – 5 detik. Arus laut berperan dalam penguatan tinggi gelombang. Pada musim barat tinggi gelombang signifikan bertambah dari 0,44 m menjadi 0,5 m sementara pada musim timur bertambah dari 0,35 m menjadi 0,37 m. Spektrum energi gelombang di Teluk Jakarta menunjukkan pengaruh Sea lebih dominan pada musim timur semantarapengaruh Swell lebih dominan pada musim barat. Pengaruh arus mengubah kondisi gelombang di Teluk Jakarta baik Sea maupun Swell pengaruhnya dominan pada musim timur.Kata kunci : Model Gelombang, Variasi Musim, Pengaruh ArusInformation about ocean wave characteristics is very important for working on various activities in the ocean such as fishing, navigation, coastal and offshore engineering. This information can be derived from long termfield observation, but this would require substantial amount of money. With ever increasing computer capabilities such information could be derived by applying a numerical model. In this research third generation wave model, WAM Model Cycle 4, was applied to study wave characteristics in Java Sea and wave energy spectrum in Jakarta Bay. The model was applied for two conditions i.e west and east monsoons and theinfluence of current on wave was also taken into consideration. Simulation results indicate that significant wave height during west monsoon is higher than east monsoon. Significant wave height and peak period during west monsoon vary between 0,44 – 1,83 m and 2 – 5 second respectively while during east monsoon they vary between 0,35 – 1,06 m and 2 – 5 second respectively. Ocean current causes wave height to increase. During west monsoon significant wave height increases from 0,44 m to 0,5 m while during east monsoon it increases from 0,35m to 0,37 m. Wave energy spectrum of Jakarta bay indicates that Sea is more dominant during east monsoon while Swell during west monsoon. The influence of current changes the wave condition in which both Sea and Swell are dominant during east monsoon.Key words : Wave model, Seasonal variation, Effect of ocean current.
Kajian Lokasi Upwelling untuk Penentuan Fishing Ground Potensial Ikan Tuna Kunarso, Kunarso; Hadi, Safwan; Ningsih, Nining Sari
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 10, No 2 (2005): Jurnal Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

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Abstract

Ikan tuna adalah penyumbang devisa negara dari sektor perikanan yang tinggi.Penentuan lokasi fishingground yang tepat perlu dilakukan untuk  mengoptimalkan penangkapannya. Lokasi upwelling sebagai daerah yang subur perlu dikaji keterkaitannya dengan fishing ground tuna. Tujuan penelitian ini adalah mengkaji kaitan antara lokasi upwelling dengan fishing ground potensial ikan tuna. Metode penelitian ini menggunakan analisis diskriptif dengan membandingkan data karakteristik lokasi upwelling , bioekologi dan perikanan tuna. Berdasarkan hasil analisa ditemukan bahwa lokasi upwelling merupakan fishing ground  tuna yang potensial. Dengan meng-overlay (penampalan) peta distribusi tuna dan lokasi upwelling, telah diperoleh peta lokasi prediksi fishing ground tuna yang potensial berdasarkan variasi bulan dan tipeperiode kejadian iklim (Normal, El Niño, dan La Niña)Kata kunci : tuna, lokasi upwelling, lokasi penangkapanTuna fishes give high contribution to the country devisa. Determination of proper fishing ground isnecessary to be done in order to optimallize the tuna catch. The upwelling location, as the fertile area, andits correlation with tuna fishing ground are necessary to be studied. The aim of this research was studyingcorelation between upwelling location with tuna fishing ground. Metode of this research used was descriptionanalysis with compare upwelling characteristis, bioecology, and tuna fishing data. Based on analysis of the result, it is found that upwelling location is potential tuna fishing ground. By overlying, we have produced the monthly prediction map of potential tuna fishing ground and its relation to climate variability (e.g., Normal, El Niño, and La Niña events).Key words : tuna, upwelling, fishing ground
Perubahan Kedalaman & Ketebalan Termoklin pada Variasi Kejadian ENSO, IOD & Monsun di Perairan Selatan Jawa Hingga Pulau Timor ( Charge of Thermocline Thickness & Depth on the Variation of ENSO & IOD Events in the Waters of the Southern Java to Timor Isl) Kunarso, Kunarso; Hadi, Safwan; Ningsih, Nining S; Baskoro, Mulyono S
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 17, No 2 (2012): Jurnal Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

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Abstract

Lapisan termoklin berperan dalam identifikasi kedalaman lapisan renang dari ikan tuna. Identifikasi perubahan kedalaman termoklin pada variabilitas ENSO (El Nino Southern Oscilation), IOD (Indian Oscillation Dipole Mode) dan Monsun, dikaji berdasarkan data CTD(Conductivity-Temperature-Depth) dan argofloat yang terakumulasi dalam Word Ocean Data (WOD) dari tahun 1985–2011. Data angin dari National Centre for Environmental Prediction (NCEP), data-data intensitas hujan dari Badan Meteorologi dan Geofisika (BMG) dan data-data indek anomali iklim global (SOI SouthOscillation Index), NINO3.4 dan IOD) digunakan untuk melengkapi analisis permasalahan. ENSO, IOD dan Monsun ditemukan semuanya berpengaruh terhadap kedalaman batas atas, batas baw ah, dan ketebalan termoklin. Secara umum ditemukan kedalaman batas atas pada musim timur lebih dalam daripada saat musim barat. Berdasarkan variasi antar tahunan iklim global ditemukan bahwa batas atas pada kejadian El Niño umumnya lebih dangkal (rerata 50,9–51,7 m) daripada saat La Niña (rerata 58,4–60,2 m). Sebaliknya batas bawah termoklin pada saat El Niño ditemukan lebih dalam (rerata 262,9–281,8 m) daripada saat La Niña (rerata 204,5–259,6 m). Ketebalan termoklin pada saat El Niño ditemukan umumnya lebih tebal (rerata 211,2–230,9 m) daripada saat La Niña (rerata 144,4–201,2 m). Faktor tingginya curah hujan sebagai indikator besarnya tutupan awan berpengaruh terhadap batas bawah termoklin, semakin tinggi curah hujan maka semakin dangkal batas bawah termoklin. Disamping faktor tersebut faktor tingginya anomali SST (seawater surface temperature) di NINO3.4 dan besarnya nilai IOD berpengaruh terhadap variabilitas kedalaman batas atas dan batas bawah termoklin. Semakin tingginya nilai anomali SST di NINO3.4 dan semakin besar nilai IOD (+) maka batas atas termoklin akan semakin dangkal dan batas bawahnya makin dalam. Kata kunci: Termoklin , ENSO, IOD, Monsun, perairan selatan Jawa, Timor   Thermocline layer is needed on depth identification of tuna-like fish swimming area. Identification of thermocline depth changes due to ENSO (El Nino Southern Oscilation), IOD (Indian Oscillation Dipole Mode) and monsoon variability were determined based on CTD(Conductivity-Temperature-Depth) and argofloat data accumulated in the Word Ocean Data (WOD) from 1985–2011. The wind data was collected from National Centre for Environmental Prediction (NCEP), rainfall intensity (from Indonesian Meteorology and Climatology Agency), and climate anomaly index of global climate change (SOI (SouthOscillation Index), NINO3.4 and IOD) were also used to support problem analysis. ENSO, IOD and monsoon determined as influencing upper and lower threshold and thermocline thickness. In general the depth of upper threshold in the eastern monsoon was deeper compare to in the western monsoon. It was also identified that, based on global climate annual variation, the upper threshold during El Niño fenomenon was shallower (average range of 50.9 m–51.7m) compare to the threshold during La Niña (58.4 m–60.2 m). On the other side the lower threshold during El Niño was deeper (262.9m–281.8 m) compare to the threshold during La Niña (204.5 m–259.6 m). The thermocline thickness itself during El Niño was found thicker (211.2 m–230.9 m) compare to La Niña (144.4 m–201.2 m). Heavy rainfall precipitation, as an indicator of cloud coverage, was determined as influencing the thermoc line lower threshold where the bigger rainfall precipitation the shallower lower threshold found. The high anomaly of Sea Surface Temperature (SST) in NINO3.4 and high value of IOD was also significantly influenced the thermocline upper and lower threshold variability. The higher anomaly value of SST in NINO3.4 and the bigger IOD(+) value resulting shallower upper threshold and deeper lower threshold. Key words: Thermocline, ENSO, IOD, Monsoon, southern waters of Java, Timor
Studi Dinamika Ekosistem Perairan Di Teluk Lampung: Pemodelan Gabungan Hidrodinamika-Ekosistem Koropitan, Alan Frendy; Hadi, Safwan; Radjawane, Ivonne M.; Damar, Ario
Jurnal Ilmu-Ilmu Perairan dan Perikanan Indonesia Vol 11, No 1 (2004): Juni 2004
Publisher : Institut Pertanian Bogor

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Abstract

Penelitian ini bertujuan untuk mengkaji dinamika ekosistem perairan di Teluk Lampung dengan menggunakan gabungan model hidrodinamika-ekosistem dengan pendekatan numerik. Secara umum, hasil simulasi pola arus residu M2 cenderung masuk dari mulut teluk sebelah barat, sebagian terus memasuki sampai kepala teluk dan sebagian keluar kembali dari mulut teluk bagian timur. Selain itu, terlihat pula adanya suatu eddy yang mengalir berlawanan arah jarum jam di sekitar kepala teluk. Pola penyebaran masing-masing kompartimen ekosistem hasil model memiliki kesamaan dengan hasil pengamatan di lapangan, serta konsisten dengan pola arus residu M2. Pengaruh suplai dari sungai, interaksi antara proses biologis seperti produktifitas primer, sekunder (pemangsaan), kematian alami plankton, serta proses dekomposisi oleh bakteri belum begitu berperan dalam neraca dan standing stock ekosistem di Teluk Lampung. Peranan suplai dari laut lebih dominan dibanding dengan proses-proses biokimiawi yang berinteraksi di dalam teluk. Hasil perhitungan tingkat efisiensi aliran energi dari proses dekomposisi dan produksi urine zooplankton ke produktifitas primer mengalami kehilangan sebesar 30.48 %, sementara dari produktifitas primer ke produktifitas sekunder (pemangsaan) mengalami penambahan 17.24 %.Kata kunci: dinamika ekosistem, Teluk Lampung, gabungan model hidrodinamika-ekosistem, arus residu M2.
THREE-DIMENSIONAL SIMULATION OF TIDAL CURRENT IN LAMPUNG BAY: DIAGNOSTIC NUMERICAL EXPERIMENTS Frendy Koropitan, Alan; Hadi, Safwan; M.Radjawane, Ivonne
International Journal of Remote Sensing and Earth Sciences (IJReSES) Vol 3,(2006)
Publisher : National Institute of Aeronautics and Space of Indonesia (LAPAN)

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Abstract

Princeton Ocean Model (POM) was used to calculate the tidal current in Lampung Bay using diagnostic mode. The model was forced by tidal elevation, which was given along the open boundary using a global ocean tide model-ORITIDE. The computed tidal elevation at St. 1 and St 2 are in a good agreement with the observed data, but the computed tidal current at St 1 at depth 2 m is not good and moderate approximation is showed at depth 10 m. Probably, it was influenced by non-linier effect of coastal geometry and bottom friction because of the position of current meter, mooring closed to the coastline. Generally, the calculated tidal currents in all layers show that the water flows into the bay during flood tide and goes out from the bay during ebb tide. The tidal current becomes strong when passing through the narrow passage of Pahawang Strait. The simulation of residual tidal current with particular emphasis on predominant contituent of M2 shows a strong inflow from the western part of the bay mouth, up to the central part of the bay, then the strong residual current deflects to the southeast and flows out from the eastern part of the bay mouth. This flow pattern is apparent in the upper and lower layer. The other part flows to the bay head and froms an antic lockwise circulation in the small basin region of the bay head. The anticlockwise circulations are showed in the upper layer and disappear in the layer near the bottom. Keywords: POM, diagnostic mode, tidal current, residual current, Lampung Ba.
Study on Seasonal Variation of Cohesive Suspended Sediment Transport in Estuary of Mahakam Delta by using A Numerical Model Hadi, Safwan; Ningsih, Nining Sari; Tarya, Ayi
Jurnal Teknik Sipil Vol 13, No 1 (2006)
Publisher : Institut Teknologi Bandung

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Abstract. A coupled three-dimensional hydrodynamics and sediment transport model of HydroQual, Inc., (2002), ECOMSED, has been used to simulate variation of suspended cohesive sediment transport in Estuary of Mahakam Delta. The simulation results indicate that tides and seasonal variation of river discharges are the main causes of variations in the suspended sediment concentration in this area. A one-year simulation of suspended sediment distribution shows that the suspended cohesive sediment discharge to the Makassar Strait is mainly transported southward, namely through locations of Muara Jawa and Muara Pegah and seems to reach a maximum distance of distribution in January and a minimum one in October. The simulation results also show that river discharges less influence the suspended sediment concentration at Tanjung Bayur, which is located at the tip of the channel in the middle, compared to the other locations. Abstrak. Suatu model kopel tiga dimensi hidrodinamika dan transpor sedimen HydroQual, Inc., (2002), ECOMSED, diterapkan untuk mensimulasi variasi transpor sedimen kohesif melayang di Estuari Delta Mahakam. Hasil simulasi menunjukkan bahwa pasut dan variasi musiman dari debit sungai adalah penyebab utama dari variasi konsentrasi sedimen melayang di daerah ini. Simulasi satu tahun distribusi sedimen melayang memperlihatkan bahwa sedimen kohesif yang memasuki Selat Makassar terutama ditransporkan ke arah selatan melalui Muara Jawa dan Muara Pegah. Jangkauan maksimum dari aliran sedimen memasuki Selat Makassar terjadi pada bulan Januari dan minimum pada bulan Oktober. Hasil simulasi juga menunjukkan bahwa pengaruh debit sungai terhadap konsentrasi sedimen di Tanjung Bayur lebih kecil daripada di lokasi-lokasi yang lain.
INTERNAL WAVES DYNAMICS IN THE LOMBOK STRAIT STUDIED BY A NUMERICAL MODEL Sari Ningsih, Nining; Rachmayani, Rima; Hadi, Safwan; Brodjonegoro, Irsan S.
International Journal of Remote Sensing and Earth Sciences (IJReSES) Vol 5,(2008)
Publisher : National Institute of Aeronautics and Space of Indonesia (LAPAN)

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Abstract

A baroclinic 3D hydrodynamic model with the non-hydrostatic approximation called Massachusetts Institute of Technology Global Circulation Model (MIT gcm) has been applied to simulate the generation of internal tidal bores and their disintegration into internal solitary waves in the Strait of Lombok. Numerical simulation have been carried out by incorporating seasonal variations of the stratification of the water body, which exist during the first transitional monsoon, the east monsoon, the second transitional monsoon, and the west monsoon. Our simulation yields the results that the existence of the sill at the southern part of the Lombok Strait, strong tidal flow, and a stratified fluid, play an important role in forming some short of divergence and convergence area as an indication of the birth of internal waves, which are simulated on the both sides of the sill. The simulated results reproduce reasonably well the basic features of internal waves in the Strait of Lombok as captured by the Synthetic Aperture Radar (SAR) from the European Remote Sensing (ERS) satellites ERS 1 and ERS 2, such as a north-south asymmetry, propagation speeds, average amplitudes and wavelengths, and solution packets. Similiar to observations made by National Oceanic and Atmospheric Administration (NOAA) satellites, the simulation results also showed the intrusion of warmwater from thePacific Ocean into the Indian Ocean and the exitence of well-developmed thermal plume at south of the sill. Seasonal variations of interface depth of thermocline and the density difference between the stratified layers influence magnitudes of the amplitudes and wavelengths of the internal waves and solitons, and the distance of thermal plume in the Lombok Strait. It is found that during the monsoon transition periods and the west monson, the amplitudes of internal waves and solitons at the southern part of the strait is apparently larger than those at the northern one, whereas during the east monsoon, the wave amplitudes is large north of the sill than south of it. Meanwhile, the propagation speeds of northward propagating internal solitary waves (0.71-2.67m per s) are stronger than southward propagating ones (0.21-1.53 m per s) throughout the monsoon periods. Key words: internal waves, non-hydrostatic approximation, solitary waves, thermal plumes
Pola Sirkulasi Arus Dan Salinitas Perairan Estuari Sungai Kapuas Kalimantan Barat Jumarang, Muhammad Ishak; Dian Martha, Muliadi, Nining Sari Ningsih, Safwan Hadi,; Ningsih, Nining Sari; Hadi, Safwan; Martha, Dian
POSITRON: Berkala Ilmiah Fisika Vol 1, No 1 (2011)
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam, Univetsitas Tanjungpura

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Abstract

Telah dilakukan penelitian untuk mengkaji pola sirkulasi arus dan salinitas perairan estuari sungai Kapuas yang dibangkitkan oleh pasang surut, gaya pembangkit angin dan discharge sungai. Pada studi ini digunakan model numerik hidrodinamika MIKE 21 yang dikembangkan oleh DHI Water & Environment untuk mensimulasikan pola sirkulasi arus dan salinitas. Pola sirkulasi arus hasil simulasi menunjukkan pada kondisi pasang tertinggi, massa air bergerak dari utara ke selatan hingga masuk ke badan sungai sedangkan pada kondisi dan surut terendah massa air bergerak ke arah yang berlawanan (dari selatan ke utara) dan air mengalir dari sungai ke luar menuju lepas pantai. Pergerakan massa air pada kisaran kecepatan 0,05 sd 0,7 m/s. Pola sirkulasi arus baik saat purnama maupun perbani menunjukkan kesesuaian pola dan yang membedakan adalah besarnya kecepatan arus. Sebaran salinitas pada kondisi purnama (pasang tertinggi dan surut terendah) cenderung memiliki pola dan nilai yang sama dengan nilai salinitas dominan pada kisaran 33,2 s.d 33,4 PSU. Demikian pula pada kondisi perbani.