ADCIRC Simulation of Ocean Currents During Tropical Cyclone Senyar in the Malacca Strait

Abstract

Tropical cyclones are high-impact meteorological events in the near-equatorial Maritime Continent, and their influence on ocean currents in narrow, tidally energetic straits such as the Malacca Strait remains poorly quantified through hydrodynamic modeling. This study simulates the spatio-temporal evolution of ocean currents in the Malacca Strait during Tropical Cyclone (TC) Senyar (22 November-2 December 2025) using the Advanced Circulation (ADCIRC) finite-element hydrodynamic model. An unstructured mesh of 21,117 nodes and 39,205 elements, with a target resolution of approximately 2.5 km, was constructed for a domain spanning 0-8°N and 95-105°E, forced by eight tidal harmonic constituents and by ERA5-derived, OWI-formatted wind and pressure fields describing the TC Senyar wind field, using a two-day hyperbolic-tangent ramp to avoid spurious transients. Results show that current speeds intensified from a near-zero pre-cyclone state to a domain-wide maximum of 1.89 m/s, concentrated in the narrow channels of the southern Malacca Strait near the Riau Archipelago, during the intensification and peak phases of the cyclone. Time series extracted at five representative locations (Belawan, Kuala Tanjung, and the northern, central, and southern Malacca Strait) indicate that the southern strait experienced the strongest mean (0.316 m/s) and maximum (0.680 m/s) current speeds, while tidal periodicity persisted throughout the cyclone lifecycle, with the storm primarily modulating current magnitude rather than reversing the dominant semidiurnal flow pattern. These findings demonstrate the capability of ADCIRC to resolve tropical-cyclone-modulated coastal current dynamics in a monsoon- and tide-dominated strait.