Response of Sea Surface Temperature (Sst) and Chlorophyll-a on Madden Julian Oscillation (Mjo) in Indonesian Seas

Madden-Julian Oscillation (MJO) is a large-scale phenomenon that occurs in equatorial area, parti-cularly Indonesia. This research aimed to investigate the MJO propagation process and studied the correlation between MJO and sea surface temperature (SST) and chlorophyll-a. Sea variables (SST and chlorophyll-a) and atmosphere variables (outgoing longwave radiation/OLR, 1,5 km wind, and surface wind) were band-pass filtered for 20-100 days period. Spectral density from OLR and 1,5 km wind (2003-2012) shows that the MJO period was dominantly occurred for 40–50 days. Average pro-pagation of MJO velocity resulted from the atmospheric variable analysis by Hovmöller diagram was 4,7 m/s. Cross correlation between SST and OLR in South Java and Banda Sea results a strong corre-lation during MJO active phase, where MJO took place first and was then followed by the decreasing SST along the equatorial region. Increasing chlorophyll-a concentration occured at some areas du-ring MJO active phase with relatively short phase delay. During the MJO active phase, fluctuation of wind velocity generates variation over mixed layer depth and triggers upwelling /entrainment. Nutri-ent was upwelled to the water surface and hence increase phytoplankton production and chlorophyll-a concentration

Studi Dinamika Ekosistem Perairan di Teluk Lampung: Pemodelan Gabungan Hidrodinamika-Ekosistem

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 %

Cohesive Sediment Transport Modeling on Inner Ambon Bay

The presence of cohesive sediment in the water column can reduce light penetration and affect photosynthesis process, and it can be disrupted the primary productivity of aquatic, and sedimentation of coastal waters. The objective of this research was to determine the cohesive sediment distribution pattern and the relationship with sedimentation. MIKE 3 FM modeling was used to understand the process of sediment transport and sedimentation on Inner Ambon Bay. Sediment transport modeling method was divided into two stages: the hydrodynamic modeling (baroclinic) and sediment transport (mud transport) modeling. The model results indicate current patterns in the Inner Ambon Bay is influenced by the tidal factor. Suspended sediment dispersed vertically from the surface to a depth of 30 m with concentration of about 3.5-15 Kg/m3. The maximum consentration of the suspended sediment occurs at head of the bay (around Waiheru, Passo, and Lateri). Model simulations for 30 days showed the rate of erosion is about 1.04-6.15 Kg/m2/s, while in Inner Ambon Bay the erosion about 9.07x10-8Kg/m2/s only occurred in T1 station. Sedimentation associated with the cohesive sediment accumulation and it was shown by bed level. In addition, the simulation showed bed level in sill ranged at 0.01-0.19 cm and 0.47 mm/day on average, while in the Inner Ambon Bay it ranged from 1.75-10.01 cm, and the sedimentation rate was approximately 39.9 mm/day

Sediment Accumulation Profile in Mangrove Restoration Area of Lembar Bay-lombok Island

Mangrove restoration is really needed for restoring its ecosystem functions, so that it could be able to support fisheries activity and to protect coastal by extreme weather. In addition, mangrove is able to accumulate sediment that important in protecting the coastal area from sea level rise. Therefore, the aim of this study is to investigate sediment accumulation rate in mangrove area during post restoration. Sampling location were divided into three different stations based on estimated restoration ages, such as ≥ 15 years old (Station 1), 4 - 10 years old (Station 2) and 2 - 8 years old (Station 3). Sediment cores were carried out by inserting 7.6 cm diameter and 100 cm length of polyvinyl chloride pipes. Sedimentation rate is measured by using Pb-210 radionuclide analysis. The results show that the sediment accumulation rate in the last 20th years from all station ranges from 0.17 to 0.42 g/cm2/year. The highest accumulation rate is found at oldest year old station while the lowest accumulation rate is found at younger year old station of mangrove restoration area. Restoration process is clearly able to recover the mangrove\u27s role in trapping sediment in coastal region

COHESIVE SEDIMENT TRANSPORT MODELING ON INNER AMBON BAY

The presence of cohesive sediment in the water column can reduce light penetration and affect photosynthesis process, and it can be disrupted the primary productivity of aquatic, and sedimentation of coastal waters. The objective of this research was to determine the cohesive sediment distribution pattern and the relationship with sedimentation. MIKE 3 FM modeling was used to understand the process of sediment transport and sedimentation on Inner Ambon Bay. Sediment transport modeling method was divided into two stages: the hydrodynamic modeling (baroclinic) and sediment transport (mud transport) modeling. The model results indicate current patterns in the Inner Ambon Bay is influenced by the tidal factor. Suspended sediment dispersed vertically from the surface to a depth of 30 m with concentration of about 3.5-15 Kg/m3. The maximum consentration of the suspended sediment occurs at head of the bay (around Waiheru, Passo, and Lateri). Model simulations for 30 days showed the rate of erosion is about 1.04-6.15 Kg/m2/s, while in Inner Ambon Bay the erosion about 9.07x10-8Kg/m2/s only occurred in T1 station. Sedimentation associated with the cohesive sediment accumulation and it was shown by bed level. In addition, the simulation showed bed level in sill ranged at 0.01-0.19 cm and 0.47 mm/day on average, while in the Inner Ambon Bay it ranged from 1.75-10.01 cm, and the sedimentation rate was approximately 39.9 mm/day

Primary Productivity of Jakarta Bay in a Changing Environment: Climate Change and Anthropogenic Impacts

Jakarta Bay receives direct impact from the rapid development of infrastructure and landbased industries which contributed to the increase in pollution and nutrient, and at the same time facing climate change. This condition influenced growth of chlorophyll- and primary production. To investigate changes of primary production in Jakarta Bay due to anthropogenic and climate change impacts, a field measurement, laboratory experiment and collection of several data sets have been conducted. The study showed that impact of anthropogenic, particularly sediment load from the land to primary production is important. The intensification of primary production occurs in the middle region of Jakarta Bay, while the chlorophyllconcentration is high in the river mouth area. The anthropogenic impact is indicated by the land use change that has increased to 73% during the last ten years. The laboratory experiments by injecting CO in the waters, as a global warming simulation, have shown a decrease in chlorophyll- and primary production. Therefore, the combination of anthropogenic and climate changemay have a double impact on the Jakarta Bay ecosystem

Chemical Partioning of Cu and Fe in Surface Sediments on the East and West Coasts of North Sumatra

Mobilitas (termasuk proses desorpsi-absorpsi) logam berat dalam sedimen bervariasi yang bergantung pada asosiasinya pada komponen mineral dan non-mineral sedimen yang dapat juga mengindikasikan pada sumber alami dan non-alami. Penelitian ini bertujuan mengungkap kemungkinan sumber logam berat Cu dan Fe berdasarkan fraksinasi dan total logam. Lokasi penelitian terdiri dari 11 titik yang terbagi menjadi tiga bagian pesisir timur, pesisir barat, dan Pulau Nias, Sumatera Utara. Fraksi geokimia diperoleh berdasarkan prosedur ektraksi bertingkat SEP BCR (Sequential Extraction Process Bureau Commune de Reference of the European Commission) dalam empat Fase yaitu: Fraksi terlarutkan asam, fraksi tereduksi, fraksi oksidasi, dan fraksi residual. Total logam diperoleh berdasarkan metode USEPA 3050B. Pengukuran logam dilakukan dengan menggunakan spektrofotometri serapan atom (SSA). Hasil penelitian menunjukkan bahwa kegiatan antropogenik diduga menyumbang logam Fe dalam sedimen yang ditunjukkan oleh konsentrasi non residu (5,55-203,15 mg/kg) yang lebih tinggi dibandingkan fraksi residu (4,89-21,47 mg/kg). Berbanding terbalik dengan logam Cu yang asosiasi tertinggi adalah fraksi residu (2,24-8,85 mg/kg). Logam berat dalam sedimen mendapat kontribusi dari sumber alami dan antropogenik, logam Cu diduga bersumber lebih banyak secara alami dan logam Fe diduga bersumber lebih dominan dari aktifitas manusia (antropogenik) baik sekitar wilayah pesisir maupun kemungkinan berasal dari daratan