Electronic Theses and Dissertation

Selat malaka merupakan perairan strategis yang menghubungkan laut andaman dan laut cina selatan, dengan dinamika oseanografi yang dikendalikan oleh pasang surut, monsun, gradien tekanan permukaan laut, dan pertukaran massa air antarencekungan, termasuk fenomena indian ocean dipole (iod). penelitian ini bertujuan untuk menganalisis variabilitas transport volume dan salinitas di perairan selat malaka selama tiga fase iod, yaitu positif, negatif, dan normal, pada periode 2014–2024. data yang digunakan berupa data arus dan salinitas bulanan beresolusi tinggi dari model reanalisis glorys12v1 (copernicus marine environment monitoring service) serta indeks dipole mode index (dmi) dari data suhu permukaan laut ersstv5. transport volume dihitung melalui integrasi kecepatan arus yang tegak lurus terhadap penampang transek selat malaka pada lintang 5°lu, sedangkan hubungan antarvariabel diuji menggunakan koefisien korelasi pearson. hasil penelitian menunjukkan bahwa transport volume rata-rata bergerak menuju laut andaman sebesar 0,20 sv, dengan nilai maks 0,45 sv pada fase iod positif dan min −0,18 sv pada fase iod negatif yang mengindikasikan pembalikan arah arus. distribusi salinitas menunjukkan stratifikasi vertikal yang berbeda pada setiap fase. fase iod negatif menghasilkan lapisan permukaan yang lebih tawar (31,2–32,2 psu), fase iod positif menghasilkan intrusi air asin di lapisan dasar hingga 34,5 psu, sedangkan kondisi normal menunjukkan perbedaan salinitas permukaan-dasar yang lebih kecil (1,5–2,5 psu). uji korelasi antara dmi dengan transport volume dan salt transport menunjukkan hubungan yang lemah (r = 0,39–0,40; r² = 0,152–0,161). hal ini mengindikasikan bahwa iod hanya berperan sebagai modulator antar tahunan, sedangkan dinamika selat malaka secara dominan tetap dikendalikan oleh faktor lokal, seperti pasang surut, monsun, dan limpasan air tawar. kata kunci: indian ocean dipole, selat malaka, transport volume, salinitas, dipole mode index, glorys12v1

The Malacca Strait is a strategic water body connecting the Andaman Sea and the South China Sea, with oceanographic dynamics governed by tides, monsoons, sea surface pressure gradients, and inter-basin water mass exchange, including the indian ocean dipole (IOD) phenomenon. This study aims to analyze the variability of volume transport and salinity in the Malacca Strait waters during three IOD phases: positive, negative, and neutral, over the period 2014 – 2024. The data used include high-resolution monthly current and salinity data from the GLORYS12V1 reanalysis model (copernicus marine environment monitoring service) and the dipole mode index (DMI) derived from ERSSTv5 sea surface temperature data. Volume transport was calculated through the integration of current velocity components perpendicular to the Malacca Strait transect section at 5°N, while the relationships between variables were tested using the pearson correlation coefficient. The results show that the average volume transport moves toward the Andaman Sea at 0.20 Sv, with a maximum value of 0.45 Sv during the positive IOD phase and a minimum of −0.18 Sv during the negative IOD phase, indicating current reversal. Salinity distribution reveals distinct vertical stratification across phases: the negative IOD phase produces a fresher surface layer (31.2–32.2 PSU), the positive IOD phase induces saline water intrusion at the bottom layer up to 34.5 PSU, while neutral conditions show a smaller surface-bottom salinity difference (1.5–2.5 PSU). Correlation tests between DMI and volume transport, as well as salt transport, reveal weak relationships (r = 0.39–0.40; R² = 0.152–0.161). This indicates that the IOD acts merely as an interannual modulator, whereas the dynamics of the Malacca Strait remain predominantly controlled by local factors such as tides, monsoons, and freshwater runoff. Keywords: Indian ocean dipole, Malacca Strait, volume transport, salinity, dipole mode index, GLORYS12V1