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All Journal ILMU KELAUTAN: Indonesian Journal of Marine Sciences BULETIN OSEANOGRAFI MARINA
Herlina Ika Ratnawati, Herlina Ika
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Earth & Planetary Sciences

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Hubungan ENSO-IOD terhadap Curah Hujan dan Suhu Permukaan Laut di Perairan Bengkulu Maharani, Surfiarti; Ratnawati, Herlina Ika; Lubis, Ashar Muda
Buletin Oseanografi Marina Vol 14, No 2 (2025): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v14i2.69693

Abstract

Perairan Bengkulu terletak di sebelah barat Perairan Indonesia, berhadapan langsung dengan Samudera Hindia yang memengaruhi dinamika atmosfer-laut di wilayah tersebut. Penelitian ini bertujuan untuk mengetahui hubungan El Niño Southern Oscillation (ENSO) dan Indian Ocean Dipole (IOD) terhadap curah hujan dan Suhu Permukaan Laut (SPL). Data yang digunakan adalah data klimatologi (1993-2023) yang telah dikomposit dan dilakukan analisa korelasi. Hasil komposit SPL menunjukkan bahwa suhu tertinggi terjadi pada Maret–Mei (29°C-31°C), sedangkan suhu terendah pada Agustus–November (26°C-27°C). Curah hujan memiliki pola bimodial pada Maret dan Oktober/November. Hasil analisis korelasi mengindikasikan bahwa ENSO lebih memengaruhi SPL daripada curah hujan sedangkan IOD lebih dominan dalam SPL dan curah hujan. Fenomena El Niño dan IOD positif berdampak pada kurangnya curah hujan dan memperpanjang musim kemarau, sementara La Niña dan IOD negatif berdampak pada peningkatan curah hujan serta memperpanjang musim hujan. Hubungan El Niño dan La Niña diwakili oleh Oceanic Niño Index (ONI) terhadap curah hujan yang terjadi pada bulan September-Oktober-November (SON) dengan nilai korelasi -0.31 hingga -0.42. Sedangkan hubungan Dipole Mode Index (DMI) terhadap SPL pada periode SON menunjukkan nilai korelasi -0.70 hingga -0.78 dimana korelasi tertinggi pada Oktober (-0.78). Penelitian ini menegaskan bahwa ENSO-IOD berperan penting dalam pola iklim di Perairan Bengkulu. Bengkulu Waters are located in the western part of Indonesian Waters, directly facing the Indian Ocean, affecting the region's atmosphere-sea dynamics. This research aims to determine the relationship of ENSO and IOD to rainfall and SST. The data used are climatological (1993-2023) composited and correlation analysis is carried out. The SPL composite results show that the highest temperature occurs in March-May (29°C-31°C), while the lowest temperature is in August-November (26°C-27°C). Rainfall has a bimodial pattern in March and October/November. Correlation analysis results indicate that ENSO influences SST more than rainfall, while IOD is more dominant in SST and rainfall. Positive El Niño and IOD phenomena result in less rainfall and extended dry seasons, while negative La Niña and IOD result in increased rainfall and extended wet seasons. The ONI represents the El Niño and La Niña relationship to rainfall occurring in September-October-November (SON) with a correlation value of -0.31 to -0.42. Meanwhile, the DMI relationship to SST in the SON period shows a correlation value of -0.70 to -0.78, with the highest correlation in October (-0.78). This research confirms that ENSO-IOD plays an important role in climate patterns in Bengkulu Waters.
Analysis of Wind Characteristics and Sea Surface Elevation Dynamics in Coastal Waters of Mantang Island, Bintan Regency, Indonesia Fa'u, Yosepine Cinta Tyas Gusti; Pranowo, Widodo Setiyo; Suhana, Mario Putra; Mujiasih, Subekti; Hatmaja, Rahaden Bagas; Ratnawati, Herlina Ika; Apdillah, Dony
Buletin Oseanografi Marina Vol 14, No 2 (2025): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v14i2.70748

Abstract

Geographically, Mantang Island is situated between the Malacca Strait, Natuna Sea, and Karimata Strait, and is exposed to the open sea, which influences the oceanographic dynamics of the region. The island’s residents are heavily dependent on the sea for their livelihoods, making wind and sea tides crucial for meeting their daily needs. Consequently, this study aimed to measure wind data and sea surface elevation over a 30-day period, with the results visualized using a wind rose diagram. The specific objectives were: 1) to calculate harmonic constants using both the Least Squares and Admiralty methods to obtain FormZahl numbers, 2) to determine the characteristics of sea surface elevation based on each method, and 3) to analyze the relationship between sea surface elevation and wind speed. The findings revealed that the wind in the waters surrounding Mantang Island was primarily influenced by the monsoon, blowing from the west with maximum speeds ranging from 5.70 to 8.80 m/s. Each calculation method produced varying values for sea surface elevation, including Zo, HHWL, LLWL, MHWL, and MLWL, with respective values of 11.99 m, 15.9 m, 8 m, 17.9 m, and 6 m. FormZahl number calculations yielded values of 1.25 and 1.03 using the Least Squares and Admiralty methods, respectively. Despite the differences in the results, both methods indicated a mixed semi-diurnal tidal pattern. To examine the relationship between wind and sea surface elevation, a 6th-order polynomial regression analysis was performed. The analysis revealed a weak correlation, with a coefficient of determination (R²) of 0.21 and a Root Mean Square Error (RMSE) of 0.30. These values suggest that the model’s predictions were relatively close to actual field conditions. 
Drivers of Tidal Flooding and Coastal Vulnerability in the Riau Islands, Indonesia: A Time-Series Analysis (2022-2024) Latifah, Laila; Pranowo, Widodo Setiyo; Mujiasih, Subekti; Ratnawati, Herlina Ika; Hatmaja, Rahaden Bagas; Suhana, Mario Putra; Setiyadi, Johar; Lelalette, Johanis Dominggus; Izzaturrahim, Muh. Hafizh; Ismail, M. Furqon Azis; Syah, Achmad Fachruddin; Ryanto, Fauzan Novan; Setiyono, Heryoso; Helmi, Muhammad
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 30, No 3 (2025): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.30.3.425-437

Abstract

The Indonesian Maritime Continent is highly vulnerable to climate variability and change, as exemplified by tidal flooding events in the Riau Islands from 2022 to 2024. This study aimed to analyze the characteristics of sea level dynamics and anomalies associated with tidal flooding (rob) and identify the contributing factors. Data on tidal flooding events were gathered from press and online social media reports, while additional information on significant wave height, ocean currents, and wind was obtained from the CMEMS (Copernicus Marine Environment Monitoring Service) Marine Copernicus archives (marine.copernicus.eu). Observational data from tide gauge stations were also accessed via the IOC sea level monitoring system (ioc-sealevelmonitoring.org). The findings revealed a high probability of tidal flooding during the north wind season, particularly in January and February. Notably, tidal elevations during flooding events reached 3.06 m on January 25, 2023, 3.00 m on February 21, 2023, and 3.09 m on February 12, 2024. These events were driven by a combination of oceanographic and atmospheric factors, including high tidal ranges during spring tides, strong wind speeds averaging 19.04 to 21.43 knots in January–February 2023 and 18.65 knots in February 2024, dominant southward current patterns, and significant wave heights reaching up to 1.08 m. The alignment of the sun, moon, and earth during full and new moon phases amplified gravitational forces, causing elevated sea levels. Furthermore, strong winds during the north wind season contributed to higher wave heights, intensifying flooding impacts. Analysis of current patterns indicates that the highest speeds were recorded during the northern wind season, specifically in January and February, which coincides with the tidal flooding events. The currents predominantly moved southward, aligning with the wind direction during this season. This study reveals oceanographic and atmospheric interactions driving tidal flooding, offering insights for mitigation and adaptation to enhance resilience in vulnerable coastal regions.
Co-Authors Ashar Muda Lubis Dony Apdillah Fa'u, Yosepine Cinta Tyas Gusti Hatmaja, Rahaden Bagas Heryoso Setiyono Izzaturrahim, Muh. Hafizh Latifah, Laila Lelalette, Johanis Dominggus M. Furqon Azis Ismail Maharani, Surfiarti Mario Putra Suhana Muhammad Helmi Ryanto, Fauzan Novan Setiyadi, Johar Subekti Mujiasih Widodo S Pranowo