Takahiro Osawa
CReSOS Unud

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STUDY OF AIR-SEA INTERACTION AND CO2 EXCHANGE PROCESS BETWEEN THE ATMOSPHERE AND OCEAN USING ALOS/PALSAR (Study Cases of Wind Wave Bubbling Process in Badung and Lombok Straits) Ekayanti, Ni Wayan; Osawa, Takahiro; Kasa, I Wayan; As-syakur, A. Rahman
Bumi Lestari Journal of Environment Vol 9, No 2
Publisher : Udayana University

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Peningkatan CO2 di atmosfer yang berpotensi menghasilkan pemanasan global telah menjadi perhatian bagi kehidupan manusia. Lautan mengandung lima puluh kali lebih besar CO2 daripada atmosfer dan menjadi penyangga yang membatasi konsentrasi CO2 dalam atmosfer. CO2 mengalami perubahan secara terus menerus antara udara-lautan dan konsentrasi CO2 di dalam laut dikendalikan oleh parameter fisika, kimia, dan biologi. Perubahan konsentrasi CO2 antara udara-lautan dapat ditentukan dari interaksi gas dan perbedaan konsentrasi CO2 antara udara-lautan. Perubahan CO2 antara udara-lautan dapat dikaji dari studi kecepatan angin, koefisien gesekan kecepatan angin yang diperoleh dari satelit ALOS/PALSAR di daerah Selat Badung dan Selat Lombok, salinitas, dan juga dengan SST yang diperoleh dari satelit MODIS. Hasil analisis menunjukkan bahwa koefisien perubahan CO2, perbedaan tekanan CO2 antara udara-lautan, dan CO2 flux antara udara-lautan secara berturut-turut yaitu 0.303±0.006 (rata-rata±standar deviasi) (mol m-2 month-1µatm-1), 17.94±10.79 ?atm, and 5.35±3.26 (mol m-2 month-1), dengan nilai maksimum dan minimum dari koefisien perubahan CO2 secara berturut-turut terjadi pada bulan Agustus dan Februari.
STUDY ON VARIABILITY MECHANISM DURING 1997/1998 ENSO IN EASTERN PART OF INDONESIA ARCHIPELAGO USING SATELLITE DATA AND IN-SITU DATA Chandra Astiti R., Luh Made; Osawa, Takahiro; Redi Aryanta, I Wayan
Ecotrophic, Journal of Environmental Science Vol 1, No 2
Publisher : Udayana University

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El Nino-Southern Oscillation (ENSO) is one of the most important climate anomalies humans isconcerned about. It brought many changes in physical of the ocean. The seas of the Indonesian Archipelagoare an artery carrying tropical thermocline water from the Pacific to the Indian Ocean. Termed theIndonesian Throughflow (ITF), this transport is driven by the Pacific/Indian interocean pressure gradient.The variability of SST in Equatorial Zone during 1997/1998 ENSO analyzed by using L1 AVHRR satelliteimages from NOAA and in-situ data from TAO/Triton buoy. This study was done in Eastern Part ofIndonesian Archipelago (110oE – 130oE and 4oS – 11oS). This research begun by collecting data in longterm, 1993, 1997, 1998 such as: in-situ data and satellite image. L1 AVHRR satellite images from NOAA toget SST data were used. From TAO/Triton buoy, SST and current data were got. SSH data available from L3TOPEX/Poseidon. SLP and salinity data were got from NOAA-CIRES Climate Diagnostics Center. All thedata analyzed by SOI value to recognize the normal, El Niño, and La Niña conditions. The SOI value wasused in this study available from existing research data.Generally, the SST in northern Lesser Sunda (Bali, Lombok, Sumbawa and Flores) was 0.5 – 1oC higherthan southern part. During El-Nino event on October 1997, the 1 – 2oC cooler SST causes the surfacepressure get higher around Indonesian seas. This phenomenon probably is much influenced by the change ofseason in Indonesia, from hot season to the rain season. But during El-Nino 1997 the 1 – 4oC warmer waterwas occurred in centre part of Pacific Ocean, hence the sea water from Indonesia Sea flown to the PacificOcean. During El Nino conditions, on December 1997, the SSH in southern Indonesia Archipelago wasabout 10 – 40 cm lower than normal conditions and became 10 – 30 cm lower than Indonesian seas. Thiscould be due to the SST in Indonesian seas was higher than southern Indonesian Archipelago causes lowersurface pressure in Indonesian seas. During La Nina conditions, on November 1998, the SSH in southernIndonesia Archipelago was about 5 – 35 cm higher than normal conditions and became higher thanIndonesian seas. This could be due to the SST in Indonesian seas was lower than southern IndonesianArchipelago causes higher surface pressure in Indonesian seas. Water mass would be flowing fromIndonesia seas to southern Indonesia Archipelago. Generally, during 1997 to 1998 the current in Java Seabecame 1 – 3 m/s stronger than normal conditions. During El-Nino 1997/1998 the sea surface temperaturein central Pacific region was warmer than usually, this could be mean the current inverse to the centralpacific from Indonesia seas. Generally, during 1997 to 1998 the current was flows southward throughMakassar Strait, continue to Lombok Strait and go to Indian Ocean. The current in Makassar Strait wasflows about 1 – 4 m/s and about 1 – 2 m/s in Lombok Strait. On June 1997 the current was flows northwardthrough Lombok Strait about 1 – 2 m/s.
STUDY OF ESTIMATE CONCENTRATION OF WATER CONSTITUENTS AT BADUNG STRAIT BALI USING INVERSE MODEL Swardika, I Ketut; Osawa, Takahiro; Arthana, I Wayan
Ecotrophic, Journal of Environmental Science Vol 1, No 2
Publisher : Udayana University

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An algorithm was employed to retrieve the concentrations of three water constituents, chlorophyll-a,suspended matter and colored dissolved organic matter (CDOM) from MODIS (Moderate-ResolutionImaging Spectrometer) in wide range covering from oligotrophic case-1 to turbid case-2 waters at theBadung Strait Bali. The algorithm is a neural network (NN) which is used to parameterize the inverse of aradiative transfer model. It’s used in this study as a multiple nonlinear regression technique. The NN is a feedforward back propagation model with two hidden layers. The NN was trained with computed radiancecovering the range of chlorophyll-a from 0.001 to 64.0 ?g/l, inorganic suspended matter from 0.01 to 50.0mg/l, and CDOM absorption at 440nm from 0.001 to 5.0 m-1. Inputs to the NN are the radiance of the fivespectral channels which were under discussion for MODIS. The outputs are the three water constituentconcentrations. The NN algorithm was tested using in-situ data set on May, September, November 2005 atthe Badung Strait Bali and the north sea of Sumbawa Island and applied to MODIS. The coefficient ofdetermination (R2) between chlorophyll-a concentrations derived from simulation and in-situ data is 0.327,for suspended matter R2 is 0.408. No in-situ measurements of CDOM available for validation. Also, in-situdata were compared with the corresponding distribution obtained by the NASA standard OC4 (OC3M) forMODIS chlorophyll-a algorithm and giving R2 0.188. This study gives better accuracy compare withstandard algorithm. How ever both studies are giving over estimate chlorophyll-a concentration. Since thereare no standard MODIS products available for suspended matter and CDOM, the result of the retrieval by theNN for these two variables could only be assessed by a general knowledge of their concentrations anddistribution patterns
EVALUATION OF TUNA FISHING GROUND IN SOUTHERN COAST OF JAVA - SUMBAWA SEA USING SATELLITE OBSERVED DATA SATIBI, MOKHLAS; OSAWA, TAKAHIRO; ARTHANA, I WAYAN
Ecotrophic, Journal of Environmental Science Vol 4, No 1
Publisher : Udayana University

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Potential fishery in territorial water of South Java - Sumbawa Sea has not been exploited maximally. Tuna is one of fisherypotency in the territorial water of South Java - Sumbawa. Tuna is the important economic value because it represent one ofexporting commodity enthused by overseas consumer.Research was conducted in the Southern Java – Sumbawa, Indian Ocean 90 S - 160 S; 1060 E - 1210 E, using fish catch data2003 – 2006. Research location is in the inclusive Region of Fishery Management IX (DKP and PKSPL, 2003). Data weretaken from a daily fish catch of PT. Perikanan Samudra Besar (PSB) Benoa Bali 2003 - 2006.Sea level anomaly (SLA) data were estimated from Altimetry satellite (Jason 1), wind speed data was from Scatterometersatellite and sea surface temperature (SST) data was from Microwave satellite.Based on the result of this research, sea level anomaly of southern coast of Java-Sumbawa was fluctuated according tomonsoon. The highest bigeye tuna fish catched was 40 tuna in June 2003 and the lowest bigeye tuna fish was 2 tuna inNovember 2005. Maximum SLA observe during southeast monsoon was 21.77 cm in august 2005, while minimum SLAobserved during southeast monsoon was -18.15 cm in October 2003. Sea surface temperature of southern coast of Java-Sumbawa also fluctuated according to monsoon. Maximum SST observed during northwest monsoon was 30.450 C in March2006, while minimum SST observed during southeast monsoon was 25.050 C in August 2006. The highest wind speed was10.20 m/sec in June 2004 and the lowest was 2.00 m/sec in October 2004. Wind direction was reversely changed according tomonsoon. Northwest wind monsoon flew eastward and southeast wind monsoon flew westward.Fish production in PT PSB had been done over 4 years since 2003, in northwest and southwest monsoon in constant areaand correlation of linier regression among estimate of fish catching using SLA, SST and wind speed had no correlation. Withfish production during southwest monsoon PT PSB set in SLA negative in different temperature of 30 C, wind speed of 2.00m/sec and with abundant of fish catched. Meanwhile in northeast monsoon that was in positive SLA the fish catching was inlow number.
STUDY OF TOTAL SUSPENDED MATTER DISTRIBUTION USING SATELLITE DATA AND NUMERICAL SIMULATION IN PORONG SIDOARJO, EAST JAVA -, Herman; Osawa, Takahiro; Arthana, I W
Ecotrophic, Journal of Environmental Science Vol 5, No 1
Publisher : Udayana University

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Sedimentation is one of coastal dynamic processes. Sedimentation in the mud volcano of Porong at Sidoarjo is an important phenomena to be known as a reference to find out a good solution in the tragedy of mud volcano eruption. Observation of the sedimentation process in the mud volcano eruption of Porong Sidoarjo needs in situ data and data processing technique to know of more details about sedimentation process and the main cause of the sedimentation and the large mud volcano eruption. Therefore, studying of sedimentation process needs the quick timing and high accuracy method. One of the technique which can be used is remote sensing method compared with numerical model and in situ data oservation. Study area is in the Regency of Porong Sidoarjo Province of East Java on August 2008 in position of 7°30’ S - 7°40’ S and 112° 30’ E - 113°30’ E. The aim of this study is to know the pattern of TSM distribution from satellite image using the algorithm which was introduced by Zhou and Kutser. The pattern of TSM from the Landsat and Modis satellite images show that the TSM distribution from the porong river, will then accumulate to the estuary. But, the concentration will decrease in the area that is far from the estuary. This is caused by the influence of the tide current in the Madura strait.From the simulation model was shown that the sediment distribution is influenced by pattern of current generated by tide. High tide where the current move to the upstream sediment in the porong estuary, the sediment was then accumulated in the estuary area. However, at low tide where the current move to the downstream, sediment transportation will move out from the estuary at the maximum level. The pattern of current shows that the moving is to the south direction in the porong coastal that will cause the sediment concentration that out from the porong estuary willgo to to the south direction. The water flow in front of the mouth of porong estuary maybe one of the cause why the sediment distribution tend to move to the south direction.
STUDY OF TOTAL SUSPENDED MATTER TRANSPORTATION AND CIRCULATION IN JAKARTA BAY USING NUMERICAL SIMULATION AND SATELLITE DATA Suriwati, Luh Made; Osawa, Takahiro; Mahendra, Made Sudiana
Ecotrophic, Journal of Environmental Science Vol 5, No 1
Publisher : Udayana University

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Jakarta Bay lies in the north of Jakarta and receives freshwater run off from thirteen rivers that run through the Jakarta metropolitan area, a conurbation that is home to some 20 millions people. Total discharges of organic water pollution have experienced a rapid increase from 214 tones per day in 1980 to over 537 tones per day in 1993. This is resulted to the high nutrient levels and eutrophication of coastal waters. Input pollutant in Jakarta Bay change the natural environment condition. Eutrophication has severe local impacts in the Jakarta Bay (GEF, 2008). Study of TSM in Jakarta Bay was conducted during September 2008 to June 2009. The aims of this research were to investigate the transportations of TSM in Jakarta Bay MODIS satellite data was used and the current pattern circulation in Jakarta Bay. Methods applied were MODIS satellite data analyses from 2003 to 2005 and numerical model 2-dimensional, for the in-situ data of total suspended matter secondary data from LIPI in September 2004 was applied. To validate the result regression method was used. Validation research results using MODIS satellite analysis showed the regression coefficient is R=0.72. Vector of current in Jakarta Bay in September 2004 experienced of the change direction and speed at each condition during spring condition at flood tide 1.23 m/s, highest tide 0.77 m/s, ebb tide 0.83 m/s, and lowest tide1.31 m/s and during neap condition at flood tide 0.71 m/s, highest tide 0.69 m/s, ebb tide 0.90 m/s, and lowest tide 0.34 m/s. Transportation of TSM in Jakarta Bay are dynamic, in dry season transportation of TSM higher than rain season.
ESTIMATION OF PRIMARY PRODUCTIVITY FOR TUNA IN INDIAN OCEAN Kasma, Ende; Osawa, Takahiro; Sandi Adnyana, I Wayan
Ecotrophic, Journal of Environmental Science Vol 4, No 2
Publisher : Udayana University

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Indonesia has abundant fisheries potency, one of fisheries potency in Indian Ocean is tuna fish. Primary productivity data used as indicator of tuna fisheries potency in Idian Ocean.Research location is in Indian Ocean 070 - 210 S and 1070 - 1210 E. Weekly satellite data in 2007 used are chlorophyl, sea surface temperature, Photosynthetic Available Radiation (PAR) and euphotic zone (Zeu) data. Daily fisheries data is from tuna fish catching data 2007 in PT. Perikanan Samudera Besar (PT. PSB). Satellite data is processed by Vertically Generalized Production Model (VGPM) formula to obtained primary productivity. Tuna fish catching data correlated to satellite data to know correlation of primary productivity value to fish catching data.Result of this research is there four species of tuna fish catch in Indian Ocean, that are Madidihang or Yellowfin tuna (Thunnus albacores), Bigeye tuna (Thunnus obesus), Southtern Bluefin tuna (Thunnus macoyii), and Albacore (Thunnus alalunga). Where 73% tuna fish is Bigeye tuna. Bigeye, Albacore and Yellowfin tuna are produced annually, while Southern Bluefin tuna in northwest monsoon is no fish production. Chlorophyll-a, sea surface temperature and primary productivity value in research location are from 0,06 mg/m3 to 0,38 mg/m3, from 24,640C to 31,820C, and from 73,22mgC/m2 to 658,57 mgC/m2 respectively. Coefficient correlation in primary productivity and fish catching in fishing ground area is small (r = 0.008), its explained that, fish catching number is not influenced by primary productivity. In high or low primary productivity condition tuna fish catched in Indian Ocean area. Potential fishing ground area of Bigeye tuna, Albacore, Yellowfin and Southern Bluefin tuna in Indian Ocean are in 110 – 160 S and 1060 – 1210 E, the primary productivity value is from 73 mgC/m2day to 732 mgC/m2day and differences of sea surface temperature value of tuna fish are from 240 C to 310 C, 240 C to 300 C, and 250 C to 310 C for Bigeye tuna, Albacore and Yellowfin tuna, respectively. While Southern Bluefin tuna distribution is in temperature area from 260 C to 300 C and primary productivity value is from 92 mgC/m2day to 449 mgC/m2day
STUDY OF OCEAN CIRCULATION IN INDONESIAN ARCHIPELAGO SEA USING THREE DIMENSIONAL OCEAN MODEL Nurweda P.,, I Dewa Nym.; Osawa, Takahiro; Arthana, I Wayan
Ecotrophic, Journal of Environmental Science Vol 4, No 2
Publisher : Udayana University

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The Regional Ocean Modeling System (ROMS) was used to simulate the Indonesian Archipelago Sea current and temperature with two different vertical mixing schemes. One corresponds to the newly developed K-Profile Parameterization (KPP) scheme and the other is adapted from the stability frequency of Brunt-Vaisala Frequency mixing (BVF). It is found that, both of schemes produce reasonably realistic sea surface temperature (SST); however, the root mean square error (RMSE) values from the BVF vertical mixing were less than the KPP vertical mixing. The RMSE values from the BVF vertical mixing at northwest and southeast monsoons can be reduced down to 5.1607E-01 0C and 5.7639E-01 0C respectively. These validation results reveal that accuracy of the BVF vertical mixing is better than the KPP vertical mixing.The model results based on the BVF vertical mixing scheme show that the direction of Java Sea, Karimata and Sunda Straits surface current are strongly affected by the zonal wind system. The direction of surface current was change following the monsoonal wind system. On the other hand, the Makasar Strait surface current tend to flow southward throughout the year with annual variations in transport are related dynamically to the monsoon winds. These southward surface currents are known as Indonesian Through Flow (ITF) and it is governed by strong pressure gradient from the Pacific to the Indian Oceans. The signals of El Nino 2002 event also can be detected by the model results. It recognized that the strong Equatorial Counter Current flows to eastward to the central part of the Pacific Ocean. The Makasar Strait surface current was stronger than usual but the Karimata Strait surface current was weaker during this period.
Monitoring of Merapi Volcano Deformation Using Interferometry Synthetic Aperture Radar (InSAR) Technique Pamungkas, Ayu Margaworo; Osawa, Takahiro; Adnyana, I Wayan Sandi
Journal of Environment Vol 1, No 1
Publisher : Journal of Environment

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The Merapi volcano is the most active volcano in Indonesia until now, because of eruption occur every two or five years. To minimize the impact of volcanic eruptions need to monitor the volcanic activity, one effort in monitoring is to monitor the surface changes (deformation) around the volcano. These surface changes can be monitored with InSAR technique. In this study monitoring by analyzing the Digital Elevation Model (DEM) and displacement map from result processing using InSAR technique. The accuracy of DEM compare with Shuttle Radar Topography Mission (SRTM) DEM. These results showed that after the eruption in 2006 led to the deflation that occurred in 2007. In 2010 after the eruption led to deflation in some areas of Merapi volcano. Whereas in 2008 due to the absence of volcanic activity that occurred then the deformation is not so large changing. Test on the DEM from the process of InSAR compare with SRTM DEM produced an accuracy of 96%.
APPLICATION OF VAN HENGEL AND SPITZER ALGORITHM FOR INFORMATION ON BATHYMETRY EXTRACTION USING LANDSAT DATA Setiawan, Kuncoro Teguh; Adawiah, Syifa Wismayati; OSAWA, Takahiro; Nuarsa, I. Wayan
International Journal of Remote Sensing and Earth Sciences (IJReSES) Vol 11, No 1 (2014)
Publisher : National Institute of Aeronautics and Space of Indonesia (LAPAN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.ijreses.2014.v11.a2603

Abstract

Remote sensing technology provides an opportunity for effective and efficient bathymetry mapping, especially in areas which level of depth changes quickly. Bathymetry information is very useful for hydrographic and shipping safety. Landsat medium resolution satellite imagery can be used for the extraction of bathymetry information. This study aims to extract information from the Landsat bathymetry by using Van Hengel and Spitzer rotation algorithm transformation (1991) in the water of Menjangan Island, Bali. This study shows that Van Hengel and Spitzer rotation algorithm transformation (1991) can be used to extract information on the bathymetry of Menjangan Island. Extraction of bathymetric information generated from Landsat TM imagery data in March 19, 1997 had shown the depth interval of (-0.6) m to (-12.3) m and R2 value of 0.671. While Data LANDSAT ETM + dated June 23, 2000 resulted in depth interval of 0 m to (-19.1) m and R2 value of 0.796. Furthermore, data LANDSAT ETM + dated March 12, 2003 resulted in depth interval of 0 m to (-22.5) m and R2 value of 0.931.