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How the Impact of ENSO Events on the Indonesian Throughflow and Interannual Variability of Circulation in the Halmahera Sea
(2026-09-01)
Lubis, Muhammad Zainuddin
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Dwinovantyo, Angga
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Batara, B.
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Kausarian, Husnul
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Hidayat, Syarief
This study investigates the influence of El Niño–Southern Oscillation (ENSO) on the Indonesian Throughflow (ITF) in the Halmahera Sea (HS) during 2013–2023. Although ITF variability has been widely studied, the response of the HS to different ENSO phases remains insufficiently understood. Using a validated CROCO model, we quantified changes in HS throughflow and associated oceanographic conditions under El Niño and La Niña events. EOF analysis of sea surface height (SSH), meridional velocity, and salinity revealed dominant modes explaining more than 50% of the total variance and exhibiting clear ENSO-related variability. During El Niño events, ITF transport weakened substantially, with volume transport becoming less negative from − 4.0 ± 2.0 Sv to − 1.5 ± 1.5 Sv in the upper layer (0–100 m) and from − 5.0 ± 2.5 Sv to − 2.0 ± 2.0 Sv in the intermediate layer (0–400 m). These conditions were associated with a shallower thermocline, lower sea surface temperatures (25.5–26.0°C), and reduced surface salinity (34.74 PSU). In contrast, La Niña events strengthened the ITF, with transport reaching −7.0 ± 1.5 Sv in the upper layer and −7.0 ± 2.0 Sv in the intermediate layer, accompanied by a deeper thermocline and higher SSTs (29.8–30.42°C). The results suggest that ENSO-related variability in the HS is associated with coupled changes in thermocline structure, SSH gradients, and salinity, highlighting the importance of the HS in regulating ITF transport variability.
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How the interannual and seasonal variability in connectivity to ITF and its relation to ENSO events in the Halmahera Sea: A modeling approach and observation
(2026-02-01)
Lubis, Muhammad Zainuddin
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Hu, Song
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Simanjuntak, Andrean V.H.
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Dwinovantyo, Angga
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Arnold, Ekoué Ewane Blaise
Understanding circulation dynamics in the Halmahera Sea (HS) is essential for clarifying the interactions between El Niño and La Niña events and ITF variability, which significantly impacts the global climate. Despite studies on air-sea interactions in the HS, gaps remain regarding interannual and seasonal variability, leading to uncertainties in understanding ocean circulation and throughflow dynamics. Specifically, there is a lack of understanding of how seasonal temperature and salinity shifts influence the strength and direction of ocean currents in the HS region. This study investigated how temperature and salinity variations during interannual and different seasons affect ocean current patterns in the HS. We used the CROCO model from 2019 to 2023 and observed it in September 2021. Our findings indicate distinct interannual patterns in SST, with the northwest monsoon SST ranging from approximately 28.3–29.8°C and the southeast monsoon SST ranging from approximately 26.8–29.0°C. The SSS varied between approximately 34.1 and 34.6 PSU, with the maximum mean water mass transport in the subsurface recorded at −0.5479 ± 0.6583 Sv at 0.5°S, indicating transport toward the Banda Sea. The SSH ranged from ∼0.69 to ∼0.73 m in the northwest and ∼0.66 to ∼0.69 m in the southeast monsoon. The densities at the surface, subsurface, and intermediate layers were 22.5, 25.5, and 26.5 σ<inf>ѳ</inf>. This research advances our understanding of the factors affecting HS circulation dynamics and their responses to El Niño and La Niña events, paving the way for Indo-Pacific water exchange studies.
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Annual analysis of surface temperature, land cover, and precipitation impacts on durian harvests in Thailand
(2026-01-01)
Lubis, Muhammad Zainuddin
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Dwi Wulandari, Pratiwi
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Simanjuntak, Andrean V.H.
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Batara, B.
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Kausarian, Husnul
This study analyzes the impact of land surface temperature (LST), NDVI, land cover, precipitation, and climatic factors on durian productivity in Thailand (2019–2025). Results show a significant positive correlation between LST and durian yields, particularly in the southern regions, where LST increased by 0.2–0.3 °C. Statistical models indicate that the southern sector will contribute over 50% of the national durian harvest by 2025, with an average yield of 617,990 tons. The precipitation and NDVI trends also correlate with regional variations in yield. The results underscore the complex interactions of temperature, land cover, and precipitation, emphasizing the need for targeted adaptation strategies and integrated planning to sustain agricultural productivity. These findings highlight the critical role of climate variables in shaping durian productivity and stress the importance of adaptive strategies to ensure sustainable agricultural output.
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Decadal and seasonal oceanographic trends influenced by climate changes in the Gulf of Thailand
(2025-06-01)
Lubis, Muhammad Zainuddin
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Ghazali, Muhammad
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Simanjuntak, Andrean V.H.
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Riama, Nelly F.
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Pasma, Gumilang R.
Our study investigates the decadal and seasonal variability of sea surface height (SSH) and sea surface temperature (SST) in the Gulf of Thailand (GoT) using data from CMEMS from 1993 to 2021. We employed statistical analyses utilizing GLM and GAM to assess the variables comprehensively. The reveals a significant upward trend in SSH, increasing from ∼0.79 m in 1993–1998 to ∼0.89 m in 2017–2021, highlighting the impacts of climate change. SST analysis revealed fluctuations, with a maximum reaching ∼30.6 °C in 2019–2020, correlating with climatic events such as El Niño. Our study results at station 1 (near Bangkok) showed that the average SSH in 1998 during strong El Niño years was equal to 0.82 m, while the maximum SST was equal to 29.89 °C. Seasonal patterns indicated SSH peaks in DJF and SON at ∼0.92 m, while SST peaked in spring MAM and summer JJA at ∼30.7 °C. Volume transport analysis showed significant variability, with 0.3634 Sv (0–55 m) at longitude 99°E-107° E and latitude 6° N, indicating complex circulation patterns influenced by bathymetry and wind. Time series analysis revealed an average SSH increase of 0.0038 m/year, with a high pseudo-R-squared of 0.99. Our findings underscore the critical influence of climate variability on oceanographic conditions in the GoT, emphasizing the need for ongoing monitoring to address the implications of rising sea levels and temperature fluctuations. In conjunction with increased SSH, the rising SST heightens the risk of flooding in low-lying areas, exacerbating vulnerabilities for local populations and necessitating adaptive management strategies to mitigate these impacts.
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Satellite-derived Spatio-temporal Dynamics of Sea Surface Temperature in the Indonesian and Halmahera Seas During ENSO Events
(2025-03-01)
Lubis, Muhammad Zainuddin
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Purwanto, Budi
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Sobaruddin, Dyan Primana
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Adrianto, Dian
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Dwinovantyo, Angga
Our study investigates the satellite-derived spatio-temporal dynamics of sea surface temperature (SST) in the Indonesian and Halmahera Seas from 2019 to 2021, highlighting its implications for climate change and marine resource management. SST values range from 21.95ºC to 33.50ºC, with pronounced peaks during the East Season (June to October) and lower temperatures in the West Season (January to March). These variations are closely associated with the El Niño-Southern Oscillation (ENSO) and seasonal wind and rainfall patterns. During the East Season, we observed notable upwelling events that indicate significant ecological impacts on fish distribution and fisheries productivity. Our study employed Conductivity-Temperature-Depth (CTD) data to validate satellite observations from the Copernicus Marine Environment Monitoring Service (CMEMS). The results revealed a strong correlation between satellite and observation data (coefficients of 0.91 and 0.93), confirming the reliability of satellite data for monitoring SST in remote marine areas. Our findings underscore the critical importance of continuous SST monitoring for sustainable marine resource management and the integration of satellite data in oceanographic studies. Our study is vital for developing adaptive strategies to address climate variability, particularly El Niño and La Niña events, which significantly influence regional weather patterns and ocean dynamics and ultimately impact global climate systems. Future research should explore the long-term trends of SST toward ongoing climate change and the resilience of marine ecosystems in the face of such variability.
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Numerical simulation of hydrodynamics and measurement in the Northwest Banda Sea
(2025-03-01)
Lubis, Muhammad Zainuddin
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Simanjuntak, Andrean V.H.
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Riama, Nelly F.
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Pasma, Gumilang R.
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Dwinovantyo, Angga
This study provides critical insights into hydrodynamic and measurement techniques in the NW Banda Sea, enhancing our understanding of oceanic processes. It focuses on the physical oceanography conditions in Eastern Indonesia, demonstrating the connection between a 2D hydrodynamic model simulation and oceanographic phenomena, including surface current patterns, waves, and tides. The model analyzes the east monsoon during August, September, and October 2023, encompassing spring and neap tides. The correlation results between the model and observed tidal data over 15 days showed a strong correlation value of 0.96 and an RMSD of 0.29. The tides are predominantly mixed and semi-diurnal, reflecting the complex interplay between lunar and solar gravitational forces. Spring tides exhibit higher elevations than neap tides. The highest ocean surface current speed was observed in August at 2.23 m/s (southeast to northwest), while the lowest was noted in September at a value of 0.95 m/s (northwest to southeast). Wave patterns indicate a monthly cycle increase in wave height from September to January, with notable wave heights (Hs) and peak periods (Ts) recorded during the east monsoon from August to October. We found the interplay between surface currents and tidal patterns significantly influences wave height and current dynamics.
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Indonesian Throughflow, spatial–temporal variability, and its relationship to ENSO events in the Lombok Strait
(2025-03-01)
Lubis, Muhammad Zainuddin
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Situmorang, Edriyan
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Simanjuntak, Andrean V.H.
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Riama, Nelly F.
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Pasma, Gumilang R.
Understanding the interactions between ocean currents and climate variability is crucial for predicting future oceanic and climatic shifts in the Lombok Strait and beyond. Our study examines the Lombok Strait from 2013 to 2018, focusing on the impact of interannual and seasonal variability driven by climatic events such as the El Niño-Southern Oscillation. Our findings reveal significant fluctuations in oceanographic parameters, including temperature, salinity, and ocean currents. The lowest recorded temperature was ∼27.2 °C, and the minimum salinity was ∼32.3 psu, linked to the strong El Niño event in 2015, which altered local rainfall and evaporation patterns. Analysis of meridional and zonal velocities showed enhanced water flow, with maximum meridional velocities reaching around ∼0.04 m/s and zonal velocities peaking at ∼0.18 m/s in early 2018. Seasonal variations in sea surface height show higher values during warmer months, reflecting the influence of ENSO phenomena. The vertical distribution of salinity indicated stratification, with values ranging from ∼27.5 psu to ∼34.0 psu across different depths, corresponding to water density ranging from 22.50 σ<inf>θ</inf> to 24.0 σ<inf>θ</inf>, highlighting the interaction between Pacific and Indian Ocean waters. Water mass transport averages at 100 m and 200 m show values of −1.21 ± 0.97 Sv and −1.350 ± 1.069 Sv, with the lowest transport occurring during the summer at −1.97 Sv with a depth range of 0–100 m, suggesting robust outflow. Our findings underscore the critical role of the ITF in shaping regional oceanographic conditions and their implications for global climate dynamics.
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Development of Geomatics Technology Curriculum for Associate Degree Programs within Project-Based Learning (PBL)
(2025-01-01)
Lubis, Muhammad Zainuddin
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Sari, Luthfiya Ratna
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Chayati, Siti Noor
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Rassarandi, Farouki Dinda
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Irawan, Sudra
Geomatics technology program has strategically implemented project-based learning (PBL) in its curriculum to improve the quality of learning and prepare competent graduates in the field of geomatics. Student learning outcomes have been aligned with the Indonesian National Qualifications Framework (KKNI) Level 5, which includes capabilities in terrestrial surveying, hydrography, remote sensing, geographic information systems, and cartography. Through the PBL approach, the learning process is designed to develop students' abilities in identifying and solving real problems in the field of geomatics, as well as communicating these solutions effectively. This method encourages the development of student creativity, critical thinking, and collaboration. Alignment of Program Educational Objectives (PEOs) with the institutional mission and industry needs reflects the study program's commitment to providing superior and relevant learning experiences, as well as preparing professional and ethical graduates. The percentage of achievement of PEO and PLOs (Program Learning Outcomes) from 60% in 2019 to almost 80% in 2023, and the increase in the number of students during the period, indicate the success of the educational program in geomatics technology programs. The difference in academic achievement and behavior between the fields of hydrographic surveying (75% achievement, 17% plagiarism, 172 submissions) and oceanography (72.40% achievement, 17.40% plagiarism, 160 submissions) during 2019-2023. Through the implementation of comprehensive and integrated PBL, the geomatics technology program can effectively equip students with the technical competencies, problem-solving skills, and understanding of professional ethics needed to face challenges in the field of geomatics.

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