Climate and Seasonal Influences on Indo-Pacific Sea Level: Insights from 30 Years of Satellite and Tide Gauge Data

Authors

• Karlina Triana, Research Center for Oceanology, National Research and Innovation Agency, the Republic of Indonesia, Jakarta, IndonesiaFollow

Abstract

We analyze Indo-Pacific sea-level variability using monthly satellite altimetry (1993–2025) validated against records from 16 tide-gauge stations. Cross-comparisons show strong agreement, especially in the western Pacific, confirming the reliability of altimetry for regional assessments. Seasonal SLA variability is largest in the Bay of Bengal and South China Sea and reflects monsoonal forcing, whereas interannual fluctuations in the eastern Indian and western Pacific oceans are dominated by ENSO and modulated by PDO. Harmonic decomposition isolates annual and semi-annual cycles, and an EOF/PCA framework identifies the leading modes: EOF1 (30.8%) captures basin-scale interannual variability and EOF2 (20.9%) reflects the seasonal cycle. Spectral diagnostics indicate interannual dominance in PC1 and a clear annual peak in PC2. Attribution tests show that Niño-3.4 leads PC1 (r = −0.531), and a multiple-regression model (PC1 = Niño-3.4 + DMI + PDO) explains 45% of PC1 variance, confirming ENSO as the primary driver with additional contributions from IOD and PDO. Observed sea-level rise from altimetry and tide gauges shows overall upward trends with regional differences, and IPCC 6^th Assessment Report Sea Level Projections to 2100 highlight substantial increases and risks for low-lying coasts. These results underscore the value of integrated satellite–in situ monitoring and provide reproducible attribution of the dominant climate controls on Indo-Pacific sea level.

Keywords

sea level anomaly, satellite altimetry validation, climate index, Empirical Orthogonal Function (EOF), Indo-Pacific

Publication Date

2026

Received Date

18 June 2025

Revised Date

19 Nov 2025

Accepted Date

20 June 2026

Recommended Citation

Triana, Karlina (2026) "Climate and Seasonal Influences on Indo-Pacific Sea Level: Insights from 30 Years of Satellite and Tide Gauge Data," ASEAN Journal on Science and Technology for Development: Vol. 43: No. 2, Article 11.
DOI: https://doi.org/10.61931/2224-9028.1666
Available at: https://ajstd.ubd.edu.bn/journal/vol43/iss2/11