Spatiotemporal Variability of Chlorophyll-a in the Malacca Strait for Algal Bloom Monitoring Using Multispectral Satellite Observations
Wiliam (1*), Po-Chun Hsu (1)

1) Center for Space and Remote Sensing Research, National Central University, Taoyuan City, Taiwan

Abstract

The Malacca Strait, a narrow and ecologically sensitive maritime corridor, exhibits seasonal variation in primary productivity influenced by both monsoonal forcing and anthropogenic inputs. This study examines the spatiotemporal variability of chlorophyll-a (CHL) concentrations, a proxy for phytoplankton biomass and potential algal blooms, utilizing Sentinel-3 OLCI multispectral satellite data at 4 km resolution (1998-2024) and 300 m resolution (2017-2024). Monthly and seasonal CHL climatologies reveal a pronounced increase during the Northeast Monsoon (December-February), coinciding with positive wind stress curl patterns that indicate upwelling-favorable conditions in the central and southern parts of the strait. This suggests that monsoonal wind forcing contributes to nutrient enrichment and enhanced phytoplankton growth during this period. These findings highlight the physical-biological coupling that shapes bloom dynamics in semi-enclosed tropical seas. While multispectral data effectively capture surface CHL variability, the integration of hyperspectral remote sensing is recommended for future studies to improve species-level discrimination and enable early detection of harmful algal blooms. This research highlights the importance of satellite-based monitoring for assessing water quality and conserving biodiversity in the Malacca Strait.

Keywords: Chlorophyll-a, Northeast Monsoon, Sentinel-3 OLCI, Malacca Strait

Topic: Topic B: Applications of Remote Sensing