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61	Ocean Remote Sensing and Marine Technology	ABS-36
Generating A Monthly Variability of Sea Surface Salinity Based on Source Tracing of Salt Concentration and The Estimated SEBAL-Evaporation Mochamad Firman Ghazali*1,3, Asep Saepuloh2,3, Ketut Wikantika3,4 1. Earth Sciences, Faculty of Earth Sciences and Technology, ITB, Bandung-Indonesia 2. Geological Engineering, Faculty of Earth Sciences and Technology, ITB, Bandung-Indonesia 3. Center for remote sensing (CRS-ITB) Bandung-Indonesia 4. Geodesy and Geomatics Engineering, Faculty of Earth Sciences and Technology, ITB, Bandung-Indonesia Abstract The variation and spatial distribution of sea surface salinity (SSS) depend on the geographic condition of the water surfaces and the temporal variation of atmospheric conditions. The SSS might differ in a local coastal area compared to similar situations in global and regional oceans. The SSS values have been estimated based on spatial regression of extracted water-salt concentration as a source tracing of salt against corrected Landsat 8 satellite data during the drought season of April 2023. This result, paired with the evaporation-derived surface energy balance algorithm for land (SEBAL) algorithm, explains a monthly SSS variability after the validation using pre-defined resampled regional SSS and evaporation data. The result shows variations in estimated SSS values along with fluctuated SEBAL evaporation, describing monthly variability and the relationship between SSS and evaporation in a local coastal area limited to the condition of a drought season. The fluctuated pattern is applied for both parameters. However, the validation shows the root means square error (RMSE) values range satisfied only for the monthly variability pattern of SSS and evaporation followed by reasonable accuracy. Keywords: Monthly variability, Sea surface salinity, Local coastal area, Landsat 8, SEBAL Share Link | Plain Format | Corresponding Author (Mochamad Firman Ghazali)

62	Ocean Remote Sensing and Marine Technology	ABS-41
STRIPPED BONITO BIOMASS ESTIMATION USING BLUEROBOTICS SONAR IN BALI STRAIT AREA I Gede Merta Yoga Pratama (a*), Mutiara Rachmat Putri (a), Agus Setiawan (b) a) Faculty of Earth Sciences and Technology, Bandung Institute of Technology Jl. Ganesa No.10, Bandung 40132, Indonesia *mypratama96[at]gmail.com b) Indonesian National Research and Innovation Agency, Jakarta, Indonesia Abstract Stripped bonito (locally known as Kenyar) has a high economic value to the fishermen community around Bali Strait area. However, those traditional fishermen struggle to estimate the biomass of Kenyar below sea levels. This research aims to estimate the biomass of Kenyar using hydroacoustic method in Bali Strait area. The acoustic data was collected through 3 fishing trips in Badung Regency, using the BlueRobotics Ping Sonar Altimeter and Echosounder. The analysis results of Target Strength (TS), and the estimation of fish length, weight, and density were being validated by comparing the calculation result of the acoustic data to the 60 samples of fish measured after being caught. This research resulted that the Target Strength (TS) value is in the range of -38.5 dB to -34.5 dB, with the estimated fish length (L) of 30.4 - 52 cm, and the estimated fish weight of 1,500 - 2,500 grams. There were 223 fishes detected by the sensor with the average density of 3 ind/1000m3. The total biomass of Kenyar estimated from those 3 fishing trips is 510 kgs. Keywords: Biomass estimation, Stripped bonito, Aqoustic, Bali Strait, Target strength Share Link | Plain Format | Corresponding Author (I Gede Merta Yoga Pratama)

63	Ocean Remote Sensing and Marine Technology	ABS-57
Effect of Marine Heat Waves for Coral Bleaching in Lombok Waters Achmad Nagi 1, Susanna Nurdjaman 2, Ivonne Milichristi Radjawanne 2,3, Gandhi Napitupulu 4, Ahmad Dhuha Habibullah 1, Hansan Park 3 1. Earth Science Study Program, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jalan Ganesha 10, Kota Bandung, Jawa Barat, 40132 Indonesia 2. Oceanography Research Group, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jalan Ganesha 10, Kota Bandung, Jawa Barat, 40132 Indonesia 3. Korea-Indonesia Marine Technology Cooperation Research Center, Bandung Institute of Technology, Jl. Kebonturi Arjawinangun, Kab. Cirebon, Jawa Barat, 45162 Indonesia 4. Oceanography Research Group, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jl. Kebonturi Arjawinangun, Kab. Cirebon, Jawa Barat, 45162 Indonesia Abstract Extreme climate and weather events shape the structure of terrestrial biological systems and affect the biogeochemical functions and services they fundamentally provide for society. Coral reefs are fragile and endangered ecosystems in the tropical marine and coastal environment. Thermal stress induced by marine heatwaves (MHWs) can significantly harm coral health, leading to bleaching of the coral ecosystem. Coral bleaching occurs when corals lose their symbiosis with zooxanthellae algae due to extreme environmental stress, such as rising sea surface temperatures (SST). This study aims to quantify coral bleaching intensity in the Lombok region over recent decades, by analyzing MHWs intensity data derived from satellite-measured SST. Notably, a substantial increase in SST results in coral disassociation with zooxanthellae algae, leading to a noticeable paling of coral color. Additionally, the research establishes a direct relationship between the duration and intensity of marine heat waves and coral bleaching rates. In 1998, the coral reef area reached its peak with 36,550.71 ha. There was a sharp decline in 1999, reaching the lowest point at 4,865.76 ha. A significant increase was observed until a new peak in 2018 with 23,120.19 ha. From 2019 to 2022, there was another decline, although the area remains above the 10,000-hectare mark. The Western region experienced a significant increase from 1998 to 2018, followed by a decline. The Eastern Region showed significant fluctuations but generally trended upwards until 2018, followed by a sharp decline in 2019-2022. The Southern Region also experienced fluctuations, with an increase until 2018, followed by a significant decrease until 2022. The Northern Region showed a stable trend until 2016, then experienced a significant decline in 2017, and increased again in 2018. However, in subsequent years, the coral reef area in the Northern region remained relatively stable. Factors such as changes in sea surface temperature, hu Keywords: Coral bleaching, Lombok, Marine Heat Waves, Sea Surface Temperature Share Link | Plain Format | Corresponding Author (Achmad Nagi)

64	Ocean Remote Sensing and Marine Technology	ABS-60
Meta Model-based Optimization of Jacket Offshore Platform for Resilient Marine Infrastructures Rudi Walujo Prastianto (a*), Ferdita Syalsabila(a), Muhammad Rizky Syarifudin(a), Hastuti(a), Daniel Mohammad Rosyid(a) (a)Department of Ocean Engineering, Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember, Surabaya *rudiwp[at]oe.its.ac.id Abstract Marine infrastructure is an established sector in the blue economy of Indonesia and is expected to shift from a project to a product-based approach. At the same time, the development of the blue economy depends on the economic value that needs to cut down the construction cost for marine infrastructure. To realize this development plan, a structural design optimization framework must be initiated to design a more resilient and high-economy value infrastructure. Marine infrastructures in Indonesia are dominated by jacket-type structures suitable for shallow water. A study of design optimization for jacket-type offshore structures is conducted in this paper. The structure is designed for the Indonesia Sea located in north Gresik. The optimization is conducted with the structure limit state as the constraint as a meta-model. Variables are the dimensions of structural main members, consisting of the tubular member radius and thickness. The highest optimization ratio is achieved for wall thickness variable. The cost objective and computational effort reduction prove the feasibility propose design optimization method. Keywords: design optimization- genetic alghoritm- jacket platform- surrogate based optimization- sustainable structure- Share Link | Plain Format | Corresponding Author (Ferdita Syalsabila)

65	Ocean Remote Sensing and Marine Technology	ABS-61
Designing Sustainable Ocean Infrastructure using Reliability Based Design Optimization: A Case Study of Three-Legged Jacket Offshore Platform Rudi Walujo Prastianto, Muhammad Rizky Syarifudin, Ferdita Syalsabila, Hastuti, Daniel Mohammad Rosyid Department of Ocean Engineering, Institut Teknologi Sepuluh Nopember Surabaya rudiwp[at]oe.its.ac.id Abstract Infrastructure is essential in utilizing maritime resources and requires reliability, resilience, and cost effectiveness. In the design phase, recent developments in computational approaches have led to design optimization that relies more on science than on the engineering judgment of designers. However, the final result of design optimization is sometimes impractical and due to drastic reduction, has a lower expected lifetime. Therefore, reliability is considered during the optimization process as part of the structural evaluation. The case study for this investigation was an offshore jacket platform that consisted of three legs at Madura Sea. Within the context of the optimization process, reliability serves as a constraint. The goal is to cut down the overall weight of the structure material. The tubular elements of the jacket construction are referred to as variables. Variables are separated into several different groupings. According to the findings, taking into account the level of reliability results in a lower optimization ratio. Keywords: Design Optimization- Jacket- Madura Sea- RBDO- Reliability Share Link | Plain Format | Corresponding Author (Muhammad Rizky Syarifudin)

66	Ocean Remote Sensing and Marine Technology	ABS-70
Application of ocean colour index using the traditional Forel-Ule index in coastal waters Madihah Jafar&#8208-Sidik1, David George Bowers2, Joshua Willliam Griffiths2, Nurzaliah Ali1, Muhammad Ikhlas Zabidi1, and Saiyidah Munirah Mohd Shazali3 1. Borneo Marine Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia 2. School of Ocean Sciences, Prifysgol Bangor University, Menai Bridge, Anglesey LL59 5AB, United Kingdom 3. Razak Faculty of Technology and Informatics, Universiti Teknologi Malaysia 54100 Kuala Lumpur, Malaysia Abstract Forel-Ule colour comparator index has been used to classify the colour of natural waters like seas, lakes and rivers since the end of the 19th century. The FU index scale includes 21 different colour ranging from indigo-blue to cola-brown representative as a gradient of natural colour classification globally and intensively. We test a method for calculating the colour of the sea, as measured on the traditional Forel-Ule (FU) scale, from satellite remote sensing measurements of reflectance. Forel-Ule colour scale numbers are calculated from 46 in situ radiometer profiles in the Mozambique channel and Irish Sea and compared to direct measurements of water colour made with the FU scale. There is generally good agreement (R2&#8239-=&#8239-0.79, RMS difference&#8239-=&#8239-2.7) between observed and calculated values over the range FU2 (blue)-FU18 (greenish brown). The method is applied to map the colour, on the FU scale, of the Irish Sea using 242 in situ radiometer measurements. MODIS satellite data is used to calculate the long-term (2003-2014) average and seasonal variation of sea colour. The colour of the Irish Sea, from both in situ and satellite radiometry, shows patterns which are consistent with the known distribution and seasonal variation of suspended particles. A Forel-Ule colour scale map of western European waters shows that the most coloured waters are found in north-west European seas which are coloured by suspended sediments rather than phytoplankton blooms. Keywords: Share Link | Plain Format | Corresponding Author (Madihah Jafar Sidik)

67	Ocean Remote Sensing and Marine Technology	ABS-78
Impact of triple-Dip La-Nina to spatio-temporal chlorophyll-a concentration in Indonesian Seas Aulia Try Atmojo (a*,c), Iwan Pramesti Anwar (b,d), Maifha Linda Rusli (a), Arif Rohman (a) a) Geomatics Engineering Study Program, Institut Teknologi Sumatera, Lampung 35365, Indonesia b) Earth Science Study Program, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia (c) Division of Geodesy, Surveying and Hydrography, Geomatics Engineering Study Program, Institut Teknologi Sumatera, Lampung 35365, Indonesia (d) Oceanography Research Group, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia Abstract Suhu permukaan laut dan Klorofil-a adalah parameter kualitas perairan yang paling penting di lautan terutama kawasan pesisir. Data yang dipakai yaitu data ikan tuna, SPL dan klorofil-a dengan menggunakan citra satelit Terra MODIS dari Januari 2001 - Desember 2018. Lokasi penelitian merupakan sekitar Perairan Indonesia. Penelitian ini bertujuan untuk mengetahui sebaran SPL dan klorofil-a serta mengetahui hubungan antara SPL dan klorofil-a terhadap berat tangkapan dan landed value ikan tuna di sekitar perairan Indonesia menggunakan uji korelasi dan uji regresi linier sederhana. Keywords: La nina, Klorofil-A, Dip La nina, Indonesian Seas Share Link | Plain Format | Corresponding Author (Aulia Try Atmojo)

68	Ocean Remote Sensing and Marine Technology	ABS-83
The application of a low-cost microcomputer logger with pressure-temperature based sensor for coastal observations: A preliminary study Mona Batubara, Johan Risandi, Yaya Ulumuddin, Agus Sufyan, Khusnul Setia Wardhani, Wahyu Hendriyono, Semeidi Husrin, Aditya Pamungkas, Rahman Hidayat 1. Informatic Engineering Department, Lampung University, Lampung, Indonesia 2. Research Center for Oceanography, National Research and Innovation Agency, Jakarta, Indonesia 3. Research Center for Conservation of Marine and Inland Water Resources, National Research and Innovation Agency, Cibinong, Indonesia 4. Research Center for Hydrodynamics Technology, National Research and Innovation Agency, Yogyakarta, Indonesia 5. Research Center for Geological Disaster, National Research and Innovation Agency, Bandung, Indonesia 6. Marine Science Department, Bangka Belitung University, Kampus Terpadu UBB, Bangka, Indonesia 7. Assistant Deputy for Basic, Urban, and Water Resources Infrastructure, Deputy for Infrastructure and Transportation Coordination, Coordinating Ministry for Maritime Affairs and Investment. Abstract Nearshore hydrodynamics, such as water level, observation, plays a crucial role in understanding and monitoring the dynamics of the coastal region. The observed parameters provide insight into oceanographic processes, climate change impacts, and the behavior of marine ecosystems that could be valuable for coastal management and infrastructure planning. To date, most of the available hydrodynamic loggers are provided by companies with relatively high prices. Due to limited budgets, many areas, including Indonesia, have limited hydrodynamic observation data. In this paper, we presented a prototype of a simple (DIY-Do It Yourself) and low-cost water level logger with a microcomputer that could be applied in coastal regions. The system consists of water level and temperature sensors, a single-board microcomputer and data logger, and a power supply with different sampling frequencies for various coastal applications. The result showed the ability of the microcomputer system to measure high-resolution water levels and temperatures applicable for non-directional waves, tides and non-tides observations, and ecological monitoring. The microcomputer^s low power consumption makes it suitable for long-term coastal observations, even in remote or battery-powered applications. Moreover, the flexibility of the microcomputer system allows for customization and adaptation to specific research requirements at relatively affordable prices. Keywords: microcomputer, pressure, temperature, water level, sensor, monitoring, low-cost Share Link | Plain Format | Corresponding Author (Johan Risandi)

69	Ocean Remote Sensing and Marine Technology	ABS-84
Degree Heating Weeks (DHW) Estimation using Python Programming and Sea Surface Temperature Data from The Google Earth Engine Dataset as Coral Bleaching Analysis Tools Hariyanto Triwibowo(a), Joko Prihantono(b*), Nasir Sudirman(b), Agus Sufyan(b), Eva Mustikasari(b) a) Research Center for Oceanography, National Research and Innovation Agency (BRIN), Jakarta 14430, Indonesia b) Research Center for Conservation of Marine and Inland Water Resources, National Research and Innovation Agency (BRIN), Cibinong 16911, Indonesia *jk.prihantono[at]gmail.com Abstract National Oceanic and Atmospheric Administration (NOAA) use the Degree Heating Weeks (DHW) method as a coral bleaching alert worldwide. However, their DHW time series data is only provided in the specified virtual stations and cannot be moved as desired. In this study, DHW calculations were performed using the Python programming language and sea surface temperature (SST) data available in Google Earth Engine (GEE) datasets such as HyCom, MODIS-Aqua, NOAA Pathfinder v5.3, and NOAA OISST v2.1. This Python code allows users to calculate DHW with the desired time range and the coordinate location. Thus, the analysis and early warning of coral bleaching can be done cheaply at that location. The results show that Python code can extract the SST from the GEE dataset according to the user^s input. Then, it calculates and shows the graph of DHW showing coral bleaching alert levels. The SST data from HyCom and NOAA OISST v2.1 are preferred because they have long and continuous data ranges. Unfortunately, HyCom data was available in the GEE dataset until 8 May 2023. At the same time, MODIS-Aqua has blank data at several measurements, and the data availability starts from 2002. In the other hand, The NOAA Pathfinder v5.3 data shows unsatisfactory results because the obtained data shows several unrealistic values and blank data. Therefore, in this study, NOAA OISST v2.1 is the recommended SST data for calculating DHW. However, this program is still in development, so improvements are required to enhance its capabilities. This program will help users concerned with coral research and monitoring. Keywords: coral bleaching, degree heating weeks, python, google earth engine Share Link | Plain Format | Corresponding Author (Joko Prihantono)

70	Ocean Remote Sensing and Marine Technology	ABS-87
Spatial and temporal pattern of thermal front in Republic of Indonesia fisheries management area 571 (FMA 571) Annisa Aulia Lukman1, Ayi Tarya2, Widodo Setiyo Pranowo3,4 1Department of Earth Science, Faculty of Earth Science and Technology, Bandung Institute of Technology, Ganesha Street No. 10, Bandung, 40132, Indonesia 2Research Group of Oceanography, Faculty of Earth Science and Technology, Bandung Institute of Technology, Ganesha Street No. 10, Bandung, 40132, Indonesia 3Department of Oceanography, The Indonesian Naval Postgraduate Military Service School (STTAL), West Kelapa Gading, Jakarta, 14240, Indonesia 4Research Center for Climate & Atmosphere, National Research & Innovation Agency, Indonesia Abstract The spatial pattern of thermal front were obtained by processing sea surface temperature (SST) data using the Single Image Edge Detection (SIED) method. The aim of this research is to determine the characteristics of the thermal front in the Republic of Indonesia Fisheries Management Area (FMA) 571 based on its spatial and temporal map in the year of 2010-2020. SST & chlorophyll-a of AquaMODIS satellite imagery and FMA 571 bathymetry of the Indonesian Geospatial Information Agency datas is used in this research. This research result that the maximum & the minimum average thermal front are found in the southwest monsoon and the first inter-monsoon with values of 135 and 39 events, respectively. The maximum (minimum) SST average is 32.182oC (30.483oC) and the maximum (minimum) chlorophyll-a concentration average value is 6.547 mg/l (4.048 mg/l). Spatially numerous thermal fronts found in northern than in the southern region of FMA 571. It is indicated that thermal front formation in southern region is influenced by the variability of chlorophyll-a concentrations while in the northern region, thermal front influenced by FMA^s 571 bathymetry pattern. Keywords: thermal front, sea surface temperature, chlorophyll-a, SIED Share Link | Plain Format | Corresponding Author (Annisa Aulia Lukman)

71	Ocean Remote Sensing and Marine Technology	ABS-94
Comparison of UAV and WorldView-3 Imagery for Mangrove Species Mapping in Mundupesisir Coastal, Cirebon Muhamad Faqih Hidayatullah (a*), Umar Abdurrahman (a), Indrawan Fadhil Pratyaksa (a), Mochamad Riam Badriana (a), Chung Kyun Jeon (a, b), Ivonne Milichristi Radjawane (a, c), Han San Park (a,b) a) Korea-Indonesia Marine Technology Cooperation Research Center (MTCRC), Cirebon Center, Indonesia *E-mail: faqihhidayatullah[at]mtcrc.center b) Korea Institute of Ocean Science and Technology, Busan, Korea c) Faculty of Earth Science and Technology, Bandung Institute of Technology, Bandung, Indonesia Abstract One of the efforts for monitoring and managing mangrove areas is mapping the mangrove areas in Cirebon at the species level. This aims to explore the potential and efforts for rehabilitation, as well as an inventory of the biodiversity of mangrove areas in Cirebon, one of which is in Mundupesisir Village. Moreover, mapping of mangrove species in Cirebon is rarely studied. Therefore, the study site was located in the mangrove Kasih Sayang area, Mundupesisir Village, Cirebon Regency, West Java. High resolution remote sensing data can be used to more efficiently map mangrove species. The approach that can be used is the Geographic Object-Based Imagery Analysis (GEOBIA) method. This research aims to (1) map mangrove species using Unmanned Aerial Vehicle (UAV) data, (2) map mangrove species using WorldView-3 imagery data, and (3) compare the accuracy assessment values of mangrove species mapping results between UAV data and WorldView-3 imagery. UAV data (0.1 m) has a visible image (RGB) band, while WorldView-3 (0.5 m) is a multispectral image that has 8 bands. Field data collection was obtained and collected at purposive random sampling to identify different species based on their physical characteristics. The GEOBIA approach used includes segmentation and classification processes. The segmentation algorithm was used multiresolution segmentation. While the classification was used the Nearest Neighbor algorithm based on segmentation results. The results of GEOBIA approach successfully mapped three dominant species in the mangrove Kasih Sayang area, Mundupesisir, Cirebon, namely Avicennia marina, Rhizophora mucronata, and Acrostichum aureum. Keywords: Mangrove species, Cirebon coastal area, WorldView-3, UAV, GEOBIA Share Link | Plain Format | Corresponding Author (Muhamad Faqih Hidayatullah)

72	Ocean Remote Sensing and Marine Technology	ABS-99
Electricity Resource Assessment from Vertical Wave Height Energy Converter in Binuangeun Beach Agus Dendi Rochendi(*a,b), Dwiyoga Nugroho (b), Fadjar Hidayat (a,b), Hariyanto Triwibowo (b), Irvan Kampono (a,b), Nining Sariningsih (a), Aditya R Kartadikaria (a) a) Earth Sciences, Faculty of Earth Sciences and Technology, ITB, Bandung-Indonesia b) Research Center for Oceanography, BRIN, Jakarta -Indonesia *32422306[at]mahasiswa.itb.ac.id Abstract The south coast of Java has great potential for Wave Energy Converters (WECs). This study presents quantities of interest for wave energy converters from the vertical kinematic motion of ocean waves. The study site is located on Binuangeun Beach on the southwest coast of Java. A prototype and mechanical calculation of ocean wave energy conversion based on previous research. The data source used in this study comes from in situ measurements and wave reanalysis models. Wave height and energy dynamics are analyzed and displayed as wave spectrum and time series plots. The calculation of extreme waves is also included in the analysis. Calculation process using Python software by inserting wave height and load spectrum obtained from a significant height, peak period, and wave energy spectrum. Electricity generated from WEC is shown as average annual energy production and performance metrics. Seasonal variation of wave height provides variable power output. However, the calculation results show that the study area has a potential for wave energy above 5 kW/m, which can be applied as a test site for a wave energy conversion power plant. Keywords: WEC, Wave height, Wave spectrum, Energy conversion Share Link | Plain Format | Corresponding Author (Agus Dendi Rochendi)

73	Ocean Remote Sensing and Marine Technology	ABS-102
Empirical Model from Trios Ramses Spectral Data for Estimating the Concentration of Total Suspended Solids Syifa W. Adawiah (a,b), Supriatna (c), Masita Mandini Manessa (c), and Nanin Anggraini (d) a) Deputy for Development Policy-BRIN, Jakarta Indonesia b) Graduated Student in Marine Science Departement, University of Indonesia, Depok, Indonesia c) Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia d) Research Center for Remote Sensing -BRIN, Cibinong, Indonesia Abstract The coastal area is very strategic as the center of national economic activity. Coastal areas that have strategic value from the potential of aquatic resources and environmental services, among others, are located on the northern coast of the Java Sea, one of which is Muaragembong. The Muaragembong coast in general has a problem of decreasing water quality. One of the water quality parameters that is often used to measure conditions in the field is Total Suspended Solid (TSS). Monitoring the concentration of TSS in waters can be done through an approach, namely the development of an empirical model using remote sensing data. In addition to satellite imagery data, remote sensing data can also be performed by measuring the spectral reflection of an aquatic object using a tool called a radiometer. This study aims to build an empirical model using TRIO RAMSES data which is simulated into a combination of wavelengths from the Sentinel 2 and Landsat 8 bands to be able to estimate TSS concentrations in waters. The results showed that Reflectance Remote Sensing (Rrs) from TRIOS RAMSES data which was simulated into the wavelength range of Sentinel 2 and Landsat 8 image data was able to build an empirical model using multivariate band combinations. The results obtained on Sentinel 2 imagery show an R2 value of 0.48 and an RMSE of 37.45 in the algorithm model, where Y = 254.32x-168.04 with X the ratio of green to blue bands while on Landsat 8 where Y = 4560.9x+25.997 and X is the sum of the blue and green bands to produce an R2 of 0.44 and an RMSE of 38.54. Keywords: Empirical model- Trios Ramses- Sentinel 2- Landsat 8- TSS Share Link | Plain Format | Corresponding Author (Syifa Wismayati Adawiah)

74	Ocean Remote Sensing and Marine Technology	ABS-108
Instrumentation for Monitoring and Early Warning of Tidal Flood Using ESP32S2 Microcontroller and A01NYUB Ultrasonic Sensor in Tambakrejo, Semarang Azza Fidyani Sintania Susanti(1*), Rizki Taqwa Putranto(1), Muhamad Asqi Rahmadani(1), Ikhsan Mustaqim(1), Aloysius Dimas Sanjaya Saliyo(1), Hanna Sazidah(1), Christopher Agung Hutahaean(1), Salsabila Auliya Putri(1), Rossi Nur Iriani(2), Zinedine Wira Mulyawan(1), Moses Wicaksono Kurniawan(1), Ismi ^Alimatunnisa(1), Satria Ginanjar(1), Sekar Adiningsih(1), Anindya Wirasatriya(1), Kunarso(1), Denny Nugroho Sugianto(1), Agus Trianto(2) (1)Departement of Oceanography, Diponegoro University, Semarang, CJ 50275, Indonesia (2)Departement of Marine Science, Diponegoro University, Semarang, CJ 50275, Indonesia Abstract Tidal flood early warning system is very important to minimize the impact and loss in tidal flood-prone areas. This research proposes an instrumentation and information system for tidal flood early warning monitoring by optimizing tidal data in the local area. The efficiency of the instrumentation depends on the accuracy of the sensors installed. This research presents the testing and application of The A01NYUB ultrasonic sensor with The ESP32S2 microcontroller for technology-based water level monitoring and The Internet of Things concept in real time. The collected sensor data is analysed with an algorithm that has also been proposed in this research. The results show that the ultrasonic sensors that can provide a reliable and adequate tide monitoring scheme with an accuracy of RMSE value of 0.08943 and bias value of - 2 x 10^16. The developed system provides early warning when the sea level reaches 260-280 cm with the MSL datum reference value range of -20 cm to 40 cm. The system has been tested at the Fisherman Boat Harbor, Tambakrejo, Semarang, Central Java, Indonesia. The test has shown the accuracy of the system and has proven that the developed system will be useful to minimize the impact of the tidal flood disaster that occurs. Keywords: Early Warning System, Tidal Flood, IoT, Instrumentation Share Link | Plain Format | Corresponding Author (Algomarine FPIK UNDIP)

75	Ocean Remote Sensing and Marine Technology	ABS-115
TREKFISH Technology for fisheries conservation and management measures Indra Jaya (*), Muhammad Iqbal, Agung Tri Nugroho, Nurhaliza Amalia Lestari Dept. Marine Science and Technology, Faculty of Fisheries and Marine Sciences, IPB University, INDONESIA. (*) indrajaya[at]apps.ipb.ac.id Abstract As the fishing operations becomes more of a problem due to widespread and un-selective exploitation of fish stocks, there is an urgent need to leverage technology advancement to aid conservation and management efforts. We present and demonstrate how TREKfish technology can be used to meet this demand in this study. The TREKfish is designed to track a vessel^s position by recording its position at regular intervals, and it generates data and information such as the vessel^s position over time, from departure (leaving port), transit to the fishing grounds, and while carrying out fishing operations, and returning to port, allowing the overall footprint of the vessel to be traced from start to finish. In this study we installed TREKfish in vessels that catch Blue Swimming Crab. The distribution, abundance, and amount of catch per unit of effort (CPUE) can be mapped and computed based on the accumulation of fishing activity records. This CPUE information is critical for sustainable fisheries management. It will also be able to assist in understanding the state of targeted fish stocks (i.e. Blue Swimming Crab) and identifying conservation or limited areas in the fishing grounds. Keywords: TREKfish, VMS, conservation area, management measures, sustainable fisheries Share Link | Plain Format | Corresponding Author (INDRA JAYA)

76	Ocean Remote Sensing and Marine Technology	ABS-127
Application of Geoid and Mean Dynamic Topography Models as an Alternative to the Mean Sea Level Approach in Determining Vertical Datum (Case Study: Java Island and Surrounding) Dina Anggreni Sarsito, Muhammad Syahrullah, Brian Bramanto, Heri Andreas, and Dhota Pradipta Geodesy Research Group, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung, Indonesia Abstract Indonesias archipelagic territory provides constraints for determining a seamless vertical datum throughout the region. The main constraint is how to connect the vertical datum between islands separated by sea. To define the physical height system of land areas, it usually refers to the Mean Sea Level (MSL), which has different values in each area, and the ideal MSL information is not yet available throughout regions with a minimum data duration of one cycle of 18.6 years. To overcome this constraint, in this research, another alternative method is used: applying a vertical datum that refers to a physical geoid reference surface, namely Mean Dynamic Topography (MDT) using Altimetry satellite data. The study area is Java Island and its surroundings, using vertical information from Geodetic Control Point stations, which also function as Tidal stations in the Indonesian Geospatial Reference System network. The range of MDT deviation values obtained from the Satellite Altimetry with Geodetic Ground Control data is 2 meters, which is a good value for coastal areas facing the open sea. This shows that the application of the geoid and MDT models can be used as an alternative, seamless MSL approach in the Java Island region and its surroundings. Keywords: Vertical Datum- Geoid- Mean Dynamic Topography- Mean Sea Level Java Share Link | Plain Format | Corresponding Author (dina anggreni sarsito)

77	Ocean Remote Sensing and Marine Technology	ABS-128
Shoreline change analysis using satellite imagery for Bungko Lor Village, Cirebon Coastal Area, Indonesia U Abdurrahman1, A P Khairunnisa2, I M Radjawane1,2*, I F Pratyaksa1, A A Nur1, M R Badriana1, C K Jeon1,3, H S Park1,3 1 Korea-Indonesia Marine Technology Cooperation Research Center (MTCRC), Cirebon Center, Indonesia 2 Faculty of Earth Science and Technology, Bandung Institute of Technology, Bandung, Indonesia 3 Korea Institute of Ocean Science and Technology, Busan, Korea Abstract Shoreline changes have recently become a concern for low-lying coastal areas and are reviewed from a regional to local spatial scale. Bungko Lor, a village in Kapetaka District, Cirebon Regency, Indonesia, has fairly high land use for fish- and salt-pond, making it vulnerable to shoreline changes. This study aims to show the application of shoreline change analysis at a local spatial scale and focuses on detecting shoreline changes in the period 2012 - 2021. The Digital Shoreline Analysis System (DSAS) was applied to the satellite imagery dataset consisting of Landsat 7, Landsat 8, and Sentinel 2 to estimate the shoreline change rate. High accuracy and resolution shoreline was described from drone image for validation and showed values of 0.863 and 4.997, for R2 and RMSE respectively. Changes in the shoreline during 2012 - 2016 indicate a sedimentation trend, while during 2017 - 2021 show an abrasion trend. Overall, in 10 years, the shoreline change trend in Bungko Lor Village is abrasion, with an average abrasion rate of -2.39 m/year and net shoreline movement towards land with a value of 59.99 m. Sediment transport variability was also estimated and resulted in 2.49 kg/s during the west monsoon and 2.33 kg/s during the east monsoon. Sediment transport is dominated by a direction towards the south and waves that also have the same dominant direction, from north and northeast. This study shows that shoreline change studios can also be applied on local scale and reveals the temporal and spatial dynamics within the area. Keywords: Shoreline changes, satellite imagery, DSAS Share Link | Plain Format | Corresponding Author (Ivonne Milichristi Radjawane)

78	Ocean-Atmosphere Dynamics	ABS-5
Seasonal variation in the barrier layer of the Banda Sea Mochamad Furqon Azis Ismail (a,b*), Johannes Karstensen (b) a) National Research and Innovation Agency of Indonesia (BRIN), Jakarta 10343, Indonesia *mfur00[at]brin.go.id b) GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel 24148, Germany Abstract The Banda Sea is crucial to the circulation of the world^s oceans and atmosphere due to its location within the equatorial regions of the Indonesian Maritime Continent. It links the Pacific and Indian Oceans^ circulation via the Indonesian Throughflow and contributes to driving atmospheric conditions via heat and moisture fluxes. Strong salinity stratified barrier layers have the potential to play a significant role in air-sea interaction by separating the base of the mixed layer from the top of the thermocline and reducing the exchange of surface heat and momentum with the ocean^s subsurface. In this study, we present the seasonal variability of barrier layer thickness (BLT) and its formation mechanism in the Banda Sea using the eddy-resolving ocean reanalysis Bluelink version 2020 (BRAN2020) for 1993 to 2021 and air-sea flux data. The findings show that the BLT is a persistent feature in the Banda Sea with a strong seasonal cycle. The BLT maxima appear in the southeast monsoon season period from May to July and the minima in the pre-northwest monsoon season from October November. The spatial distribution of BLT is zonally oriented along the sea surface salinity (SSS) front from the west to the east of the Banda Sea. We suggest that the horizontal advection of low salinity water from the Java Sea and precipitation contributes to the formation of BLT formation and variability in the Banda Sea. Keywords: barrier layer - mixed layer - ocean reanalysis - horizontal advection - Banda Sea Share Link | Plain Format | Corresponding Author (Mochamad Furqon Azis Ismail)

79	Ocean-Atmosphere Dynamics	ABS-16
Variability of Indonesian Throughflow Transport in the Indonesian Seas during Triple-Dips La Nina Naffisa Adyan Fekranie(1,2,*), Agus Setiawan(2,*), Mutiara Rachmat Putri(3) 1) Study Program of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Labtek XI (^Labtek Biru^) 2nd Floor, Jl. Ganesha No 10, Bandung, 40132, Jawa Barat, Indonesia 2) Research Centre for Deep Sea, Research Organisation for Earth Sciences and Maritime, National Research and Innovation Agency, Indonesia 3) Research Group of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Labtek XI (^Labtek Biru^) 2nd Floor, Jl. Ganesha No 10, Bandung, 40132, Jawa Barat, Indonesia Abstract The Indonesian Seas serve as an important conduit for the Indonesian Throughflow (ITF), a critical system of warm water and freshwater transport connecting the Pacific and Indian Oceans. El Nino-Southern Oscillation (ENSO) significantly impacts the regional variability in the Pacific and exerts a profound influence on water mass transport from the Pacific to the Indian Ocean. This study focuses on the influence of triple-dips La Nina events during two distinct periods (1998 - 2001 and 2020 - 2023) on the variability of ITF transport in key areas of the Indonesian Seas, including the Makassar, Lombok, and Ombai Straits, Flores and Banda Seas, and Timor Passage. Using forecast and reanalysis data from the Copernicus Marine Environment Monitoring Service (CMEMS), transport calculations are conducted across cross-sectional profiles representing the study areas. The results reveal that the volume transport is significantly higher at depths ranging from ~50 - 300 m. It also shows seasonal fluctuations in volume transport across all regions, with lower transport during winter (DJF) and higher transport during summer (JJA) and transition period (SON) in the Makassar and Lombok Straits. In the Flores and Banda Seas, Ombai Strait, and Timor Passage, the surface transport volume follows seasonal patterns, while transport volume at deeper depths (~50 - 300 m and 300 - 800 m) exhibits distinct fluctuations compared to the surface. Triple-dips La Nina events lead to an overall increase in transport volume during both periods, with the 2019 - 2023 period showing larger transport values (~ 19 Sv) compared to the 1997 - 2001 period (~14 Sv). The strengthened ocean current velocity during Triple-Dips La Nina events results in more significant variations in total transport, leading to larger differences between minimum and maximum transport values during these periods. Keywords: ITF, Triple-Dips La Nina, volume transport, ENSO Share Link | Plain Format | Corresponding Author (Naffisa Adyan Fekranie)

80	Ocean-Atmosphere Dynamics	ABS-19
Influence of Marine Heatwaves on Upwelling Parameter in Indonesian Fisheries Management Area (IFMA) 713 Waters Ikliema Hassya Kamila (a*), Nining Sari Ningsih (b), Erlin Beliyana (c) (a) Department of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Bandung 40132, Indonesia *ikliemahassya[at]gmail.com (b) Research Group of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Bandung 40132, Indonesia (c) Doctoral Program in Earth Sciences, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Bandung 40132, Indonesia Abstract An upwelling process linked to water productivity is likely to be affected by marine heatwaves (MHWs). MHWs events characterized by warmer sea surface temperature (SST) lead to increased stratification, causing vertical mixing limits and suppressing the upwelling process. In the Indonesian Fisheries Management Area (IFMA) 713 waters, which have enormous potential for fishery resources, five upwelling areas were identified during the southeast monsoon months (May-October) based on the Ekman pumping velocity (EPV) assessment, namely locations A (western part of West Sulawesi), B (southern Makassar), C (eastern part of Bone Bay), D (southern Banjarmasin), and E (southern Makassar Strait). Therefore, this study aimed to investigate the influence of MHWs on upwelling parameter (chlorophyll-a concentration) in IFMA 713, particularly in 1998 and 2016, where prominent MHWs occurred and coincided with upwelling sessions. To accomplish this, EPV anomalies and chlorophyll-a concentrations for each MHWs event during May-October 1998 and 2016 were calculated. The analysis revealed that MHWs events co-occuring with negative (upwelling velocity is weaker than the climatological mean) and positive (upwelling velocity is stronger than the climatological average) EPV anomalies were associated with decreased chlorophyll-a concentrations. Keywords: Chlorophyll-a concentration, EPV anomalies, marine heatwaves, stratification, vertical mixing Share Link | Plain Format | Corresponding Author (Ikliema Hassya Kamila)

81	Ocean-Atmosphere Dynamics	ABS-22
Can CGCMs under CMIP5/6 simulate present-day sea level rise in western Maritime Continent? Yudha Setiawan Djamil (a*), Adinda Maharani (b), Tubagus Solihuddin (a), Martiwi Diah Setiawati (c), Aidy M Muslim (d), Tsuyoshi Eguchi (e), Uday Chatterjee (f), La Ode Alifatri (c) a) Research Center for Climate and Atmosphere, National Research and Innovation Agency (BRIN), Bandung, Indonesia *yudh006[at]brin.go.id b) PT Geosagara Triptayasa, Bandung, Indonesia c) Research Center for Oceanography, National Research and Innovation Agency (BRIN), Jakarta, Indonesia d) Institute of Oceanography and Environment (INOS), Universiti Malaysia Terengganu (UMT), 21030 Kuala Terengganu, Terengganu, MALAYSIA e) Center for Research and Application of Satellite Remote Sensing (YUCARS), Yamaguchi University, Ube city, Japan f) Department of Geography, Bhatter College, Dantan, West Bengal, India Abstract Trends of present-day sea level anomaly (SLA) in western Maritime Continent based on the combination of global thermal expansion and ocean dynamics (steric/dynamic), simulated by Coupled Global Climate Models (CGCMs) under the Climate Model Intercomparison Project phase-5 and 6 (CMIP5/6), are evaluated by using satellite observation. Trends of SLA based on the steric/dynamic component of sea level underestimate the one observed by the satellite for the interior seas of western Maritime Continent. However, satellite observation is also known to overestimate the rate of sea level rise in this shallow basin. Thus, the actual trends of SLA in this area could be approximated based on its steric/dynamic component simulated by CGCMs such as ACCESS1-0 and MIROC-ESM. Keywords: sea level, trend, CMIP5, CMIP6 Share Link | Plain Format | Corresponding Author (Yudha Setiawan Djamil)

82	Ocean-Atmosphere Dynamics	ABS-23
Extreme Marine Heatwaves in the Southern Java during 2016 Erlin Beliyana (a*), Nining Sari Ningsih (b), Ayi Tarya (b) (a) Doctoral Program in Earth Sciences, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Bandung 40132, Indonesia *erlinbeliyana99[at]gmail.com (b) Research Group of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Bandung 40132, Indonesia Abstract We investigate the characteristics of marine heatwaves (MHWs) in southern Java and the mechanism underlying the formation of MHWs generated by remote forcing. The study utilizes remote sensing data from National Oceanic and Atmospheric Administration and European Centre for Medium-Range Weather Forecasts. The datasets covered the last 40 years and were processed by statistical analysis. We found that the most prolonged durations and the highest cumulative intensities of MHWs in southern Java were recorded during 2016, spanning approximately 255 days and 419.28 degree C, respectively. During 2016, the combination of El Nino decay and negative IOD leads to optimal warm conditions for long-lasting MHWs and hit southern Java throughout the year. Furthermore, the study highlighted a stronger correlation between El Nino Southern Oscillation (ENSO) and MHWs in southern Java compared to the Indian Ocean Dipole (IOD), with a 5 to 8 months lag time. An in-depth and comprehensive understanding of MHWs becomes an urgent matter as part of a mitigation effort to deal with MHW disasters in southern Java due to ongoing climate change. Keywords: marine heatwaves- southern Java- remote forcing- ENSO- IOD Share Link | Plain Format | Corresponding Author (Erlin Beliyana)

83	Ocean-Atmosphere Dynamics	ABS-24
Sea Surface Temperature Budget in Indonesia Seas: The Role of Vertical Turbulent Mixing and its East-West Variations Faisal Amri, Ahmad Eladawy, Takashi Nakamura Transdisciplinary Science and Engineering Department, Tokyo Institute of Technology, Tokyo, Japan Abstract Vertical turbulent mixing, comprising heat and turbulent fluxes, is a key process governing the seawater temperature changes in the vertical direction. In this study, the influence of vertical turbulent mixing on surface layer temperature (i.e., a layer between free-surface to 20 m depth) in Indonesia seas were diagnosed from an eddy-permitting ocean modeling experiment results. The heat flux in the western and eastern Indonesia corresponds with surface layer cooling tendency of -1.11 and -0.24 degC month\(^{-1}\), mainly due to heat loss related to latent heat component. The turbulent flux at the base of the surface layer (i.e., 20 m depth) in western Indonesia and eastern Indonesia seas corresponds to a surface layer warming tendency of +1.14 and +0.26 degC month\(^{-1}\), respectively, counterbalancing the effect of heat flux. The average eddy diffusivity at 20 m depth in Western Indonesia (A\(_{T}\) = 0.040\(\pm\)0.017 m\(^{2}\) s\(^{-1}\)) however, was lower than in Eastern Indonesia (A\(_{T}\) = 0.049\(\pm\)0.042 m\(^{2}\) s\(^{-1}\)) suggesting the determining role of the vertical gradient of the water temperature (i.e., stratification profile) on the overall turbulent flux. Finally, study conducted here emphasizes the potential existence of distinct east-west mechanisms governing sea surface temperature variabilities in the Indonesia seas. Keywords: Ocean Modeling, Vertical Turbulent Mixing, Sea Surface Temperature, Indonesia Seas Share Link | Plain Format | Corresponding Author (Faisal Amri)

84	Ocean-Atmosphere Dynamics	ABS-27
Impacts of ERA5 Sea Surface Temperature Data on WRF Model Simulation of Extreme Rainfall Over South Kalimantan Rezky Yunita (a*), Achmad Fahruddin Rais (b), Wido Hanggoro (a), Donaldi S. Permana (a), Muhamad Rifki Taufik (a), Erwin Eka Syahputra Makmur (a), Jaka Anugerah Ivanda Paski (a), Roni Kurniawan (a), Muhamad Husein Nurrahmat (a), Thahir Daniel F Hutapea (a), Welly Fitria (a), Sri Noviati (a), Rahayu Sapta Sri Sudewi (a), Vestiana Aza (a), Fatkhurroyan (a) (a) Research and Development Center, Indonesia Agency for Meteorology, Climatology and Geophysics, Kemayoran, Jakarta, Indonesia *rezky.yunita[at]bmkg.go.id (b) Geospatial Disaster and Energy Potential Research Group, National Research and Innovation Agency, Cibinong, West Java, Indonesia Abstract This study aimed to investigate the impact of sea surface temperature (SST) on Weather Research and Forecasting (WRF) model simulation of the extreme weather events over South Borneo that occurred on 13 January 2021. There are two simulation scenarios in this study. The first scenario was conducted with NCEP Final Analysis Data (FNL) 0.25 as Boundary Condition. The second scenario was using the same boundary condition but with adjustment in the Sea surface temperature condition from ERA5 Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) data product. The result show that the rainfall amount was improved in the simulation using ERA5 Sea Surface Temperature data especially during the peak of the extreme rainfall event. This study also highlight the role of domain resolution and grid number to the extreme rainfall simulation. Keywords: WRF, ERA5, SST, Extreme rainfall, Numerical Weather Prediction Share Link | Plain Format | Corresponding Author (Rezky Yunita)

85	Ocean-Atmosphere Dynamics	ABS-37
THERMAL DISPERSION FROM THE COOLING SYSTEM CIRCULATION IN BONTANG WATERS, EAST KALIMANTAN Affan Fadli Rahmadian Bandung of Institute Technology Abstract A cooling circulation system in a Steam and Gas Power Plant (PLTUG) operates by utilizing seawater for generator cooling, leading to the production of thermal water waste as a by product. This study aims to analyze the distribution of thermal water waste in Bontang waters resulting from the PLTUG activities. To achieve this, a numerical approach utilizing the HAMburg Shelf Ocean Model (HAMSOM) was employed. The researchers developed a numerical model using baroclinic mode and initialized it with field data from May 2022. Subsequently, the model accuracy was verified against field data collected between 6th and 12th September 2022. Overall, a positive correlation was observed between the field data and the numerical model. The Root Mean Square Error (RMSE) values for current, temperature, and salinity were 0.095 m/s, 0.447 deg_C, and 0.964 psu, respectively. The study revealed that the dispersion of thermal water waste was most extensive during the full-phase low tide condition, resulting in a temperature increase of 1.5 deg_C from its initial value. Keywords: Hot Water Waste, Bontang Waters, Current Patterns, Salinity, Temperature Share Link | Plain Format | Corresponding Author (Affan Fadli Rahmadian)

86	Ocean-Atmosphere Dynamics	ABS-38
Topography Effect on Sea Breeze Front Initiated Rainfall on Summer Period in North Halmahera Vina Sabrina(a*), Nurjanna Joko Trilaksono(b), and Donaldi Sukma Permana(c) 1) Study Program of Earth Science,Faculty of Earth Science and Technology, Bandung Institute of Technology, Bandung, Indonesia 2) Indonesian Agency for Meteorology Climatology and Geophysics Abstract There are rain events that occur during the dry season in the North Halmahera region. This is thought to be due to the influence of local-scale weather phenomena that can cause rain during this period. The most dominant local scale weather phenomenon affecting weather dynamics in coastal areas is sea breeze circulation. Topographic variations can affect the strength of sea breeze, on the other hand the complexity of the coastline also impacts the propagation of sea breeze fronts. The existence of a sea breeze front can potentially produce rain clouds. In previous studies, it is known that the interaction of sea breeze front and topography can increase the intensity of rainfall in the mountain areas. This study will analyze the climatological conditions of the North Halmahera region to prove that local-scale weather phenomena are strong enough to produce rainfall in that period, then analyze the output of the WRF InaNWP BMKG model to explore the relationship between topography, sea breeze front propagation and rainfall so as to reveal the dynamics of the process when rain occurs in that period, the final stage is to verify using the eyeball and RMSE method to measure the model^s skill in predicting the weather. The results showed that climatological conditions in the period were not dominated by global and regional scale weather phenomena, but SST had enough potential to produce water vapor for convective cloud formation. The model output shows that strong convection occurs during the day and produces rain in the afternoon. This is due to the low level convergence of sea breeze circulation that combines with mountain flow from topographic effects in the northern part of Halmahera so that in the northern region the intensity of rainfall produced is greatest due to the influence of topography. The verification results show that the WRF model is able to reveal the dynamics of the rainfall process resulting from topographic effects on the sea breeze front but still underestimates the rainfall intensity compared to observations. Keywords: Topography, Sea Breeze Fornt, Precipitation, WRF Share Link | Plain Format | Corresponding Author (Vina Sabrina)

87	Ocean-Atmosphere Dynamics	ABS-45
Analysis of Extreme Wave Probabilistic Return Value based on the 20-year Spectral and Empirical Wave Modelling Approach in the Coastal Area of Pangandaran Muhammad Faizin Fitriansyah Musa (a), Wiwin Windupranata (b*), Candida Aulia De Silva Nusantara (c), Alqinthara Nuraghnia (d), Muhammad Wahyu Al Ghifari (d), Intan Hayatiningsih (b), Dudy Darmawan Wijaya (e) a) Study Program of Geodesy and Geomatics Engineering, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung b) Research Group of Hydrography, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung *w.windupranata[at]itb.ac.id c) Department of Geomatics Engineering, Faculty of Civil, Planning, and Geo Engineering, Institut Teknologi Sepuluh Nopember d) Master Program of Geodesy and Geomatics Engineering, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung e) Research Group of Geodesy, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung Abstract The Coastal Area of Pangandaran is located on the southern coast of Java Island, Indonesia. It offers stunning beach panoramas, tempting waves for surfers, while also providing livelihoods for people who depend on the marine biodiversity and abundance of fish caught in the surrounding waters. However, its exposure to the Indian Ocean makes it susceptible to extreme waves, posing risks to tourism, fishing, and safety. This study aims to conduct an extreme wave hazard analysis based on the Probabilistic Return Value (PRV) value using Significant Wave Height (SWH) data for over 20 years of data to obtain a wave climate value in the Batukaras area. The SWH values are obtained from two methods, numerical spectral wave modelling using Simulating Waves Nearshore (SWAN) and calculations using an empirical formula from the Joint North Sea Wave Project (JONSWAP), both using wind data from the ERA-5 Satellite. Based on these calculations, the Gumbel distribution was analysed to determine the PRV value on the coast. By estimating the return value of extreme waves based on the spectral SWAN method, for a return period of 300 years, extreme wave events occur at a height of 2.012 m to 2.638 m at a depth of 5-21 m. Meanwhile, the empirical JONSWAP method generates the same probability for wave heights of 7.187 m to 12.814 m based on statistical predictions based on modelling data. Based on these results, community and tourist preparedness on the coast of Batukaras Village is expected to increase, particularly during bad weather. Keywords: Extreme Wave, Spectral Wave Model, Empirical Wave Model, SWAN, JONSWAP, Probabilistic Return Value, Gumbel Distribution Share Link | Plain Format | Corresponding Author (Alqinthara Nuraghnia)

88	Ocean-Atmosphere Dynamics	ABS-46
The Study Of Ocean Wave Climate Variabilites around Indonesia Seas M A Rahman, M F Geonova, S Prasetyo, S R Adiprabowo, A Ramdhani, D S Permana Indonesia Agency of Meteorological, Climatological, and Geophysical Abstract This study investigates the spatial-temporal variations in ocean wave climate in the Indonesian seas based on 20 years of wave data from a wave model hindcast called Ina-Waves that is forced with surface winds from the GFS and NCEP-NFL for the coarse domain and a 10 km resolution WRF model for the Indonesian high-resolution domain. The hindcast data provides information on significant wave height, wave period, and wave direction, allowing for a comprehensive analysis of wave climate dynamics over an extended period. The study focuses on the influence of regional climate factors on wave patterns, such as monsoonal winds, tropical cyclones, and large-scale climate oscillations such as the Madden-Julian Oscillation (MJO), El Nino-Southern Oscillation (ENSO), and Indian Ocean Dipole (IOD). In addition, wind speed analysis was carried out to improve the assessment of the impact of regional climatic drivers. The key findings indicate that the IOD, ENSO, and MJO have a significant impact on wave conditions in Indonesian seas. Positive phases of the IOD and El Nino events are related to high wave activity in specific regions of the Indonesian seas as a result of changes in atmospheric circulation patterns, which impact trade wind patterns and result in higher wave heights in particular regions. On the other hand, negative phases of the IOD and La Nina occurrences may result in lower wave activity due to weaker trade winds. Because of its influence on atmospheric convection and wind patterns, the MJO can contribute to the variation of wave conditions in the region. It should be noted that the combined effect of these climate drivers on ocean wave height varies regionally and seasonally. Furthermore, understanding these complex relationships is essential for improving wave height forecasting and assessing the impact of climate change on coastal regions and maritime activities Keywords: ocean wave climate, spatial-temporal variations, ina-waves, indonesian seas Share Link | Plain Format | Corresponding Author (Muhammad Arief Rahman)

89	Ocean-Atmosphere Dynamics	ABS-47
The Seasonal Current in Cirebon Waters Erica M. Budiono (a), Lamona I. Bernawis (b, c), Mutiara R. Putri (b), Ivonne M. Radjawane (b, c), Rima Rachmayani (b), M. Riam Badriana (d), Arsy I. Hidayatullah (d), Ashadi A. Nur (d) a) Study Program of Oceanography, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132, Indonesia b) Research Group of Oceanography, Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132, Indonesia mail corresponding author: lamona[at]itb.ac.id c) Center for Coastal and Marine Development, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132, Indonesia d) Korea Indonesia MTCRC (Marine Technology Cooperation Research Center) Cirebon Center, Institut Teknologi Bandung, Jalan Fatahillah 24, Watubelah, Kabupaten Cirebon 45611, Indonesia Abstract The waters of Cirebon are located in the Java Sea, characterized as a relatively shallow open bay, serving as a small basin that receives numerous river flows from Java and Kalimantan islands. The purpose of this research is to investigate the seasonal distribution of surface ocean currents in the Cirebon waters. Data was collected in May (transitional season I), July (east monsoon season), and October (transitional season II) of 2022 at 12 stations scattered across the open bay of Cirebon. The velocity and direction of the currents were measured using an Acoustic Doppler Current Profiler (ADCP) installed on the research ship. The results showed that the currents predominantly moved towards the northwest during the transitional season I and east monsoon season, while during transitional season II, they predominantly moved northward in accordance with the seasonal wind patterns. The highest average current velocity occurred during the east monsoon season (0.082 m/s), followed by transitional season II (0.064 m/s), and the weakest in transitional season I (0.047 m/s). Additionally, a comparison between the observed data and Marine Copernicus reanalysis indicated a Root Mean Square Error (RMSE) value of 0.037. Keywords: Cirebon Waters- Current- Season Share Link | Plain Format | Corresponding Author (Erica Maharani Budiono)

90	Ocean-Atmosphere Dynamics	ABS-48
Upwelling Mechanism South of the Aru Islands Abdul Basit(1*), Suliskania Nurfitri(2), Mochamad Furqon Azis Ismail(1), Mutiara Rachmat Putri(2), Bernhard Mayer(3), Thomas Pohlmann(3) (1) BRIN (2) ITB (3) Hamburg University Abstract The upwelling mechanism over the continental slope south of the Aru Islands during the southeast monsoon (July 2004) was investigated using the Hamburg Shelf Ocean Model (HAMSOM). The results show that relatively strong southeasterly winds around the shelf drove relatively strong westward surface currents. In the east-west direction, by considering the volume continuity over the slope, the westward currents induce onshore subsurface currents and subsequent upward velocity below the Ekman layer, but the onshore currents and upward velocity were relatively weak. The weak onshore currents are mainly due to inhibition by northwestward geostrophic currents. In contrast, relatively strong upwelling was observed over the continental slope connecting the south of the Aru Islands and the Arafura channel (in the north-south direction). Our simulation results indicate that this strong upwelling was mainly caused by the geostrophic currents flowing northwestward, mainly generated by a horizontal pressure gradient. The gradient was due to complex topography around the west of the Aru Islands. Furthermore, the upwelling around the south of the Aru Islands is revealed by the relatively lower sea surface temperature than the surrounding. In this area, the sea surface salinity was relatively lower than the surrounding due to high river discharge from the Papua Coast. Keywords: Aru Islands, HAMSOM, Salinity, Southeast monsoon, Temperature, Upwelling Share Link | Plain Format | Corresponding Author (abdul basit)

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