Impact of Indian Ocean Vortices on Convective Activities in Western Indonesian Maritime Continent

Abstract

The Indian Ocean plays a critical role in modulating global and regional atmospheric circulation, directly influencing weather systems and energy-related processes over the western Indonesian Maritime Continent (IMC). One of the key synoptic-scale disturbances in this region is the Indian Ocean cyclonic vortex, which can significantly impact convective activity and, consequently, the availability and variability of renewable energy sources such as solar and wind energy. This study investigates the characteristics and atmospheric effects of 30 cyclonic vortex events over the Indian Ocean during the eastern monsoon period (May–September) from 2018 to 2022. Using high-resolution ERA5 reanalysis data (hourly, 0.25° × 0.25°) including sea surface temperature (SST), potential vorticity, specific humidity, precipitation, and 850 hPa winds, the vortices were classified into eastern (90°–105°E) and western (75°–90°E) groups, consisting of 17 and 13 cases, respectively. Results show that eastern vortices are generally associated with warmer SSTs (≥30.5°C) near 7°S, 99°E and exhibit stronger cyclonic circulation centered at approximately 875 hPa. These eastern vortices induce significant convective enhancement over western Sumatra through the formation of organized squall lines extending from Subulussalam to Tebing Tinggi (95°–102°E), which may influence cloud cover, rainfall intensity, and local solar irradiance. In contrast, western vortices, despite forming deep convective clouds over the ocean (90°–95°E), have limited impact on land-based convection. Both types of vortices contribute to the formation of broad convective bands stretching from western Sumatra to East Java, Bali, Lombok, and Nusa Tenggara (100°–115°E), which can affect short-term variability in solar and wind energy harvesting. These findings highlight the importance of understanding atmospheric disturbances over the Indian Ocean for developing reliable and resilient renewable energy strategies in western Indonesia.
Keywords: Vortex, Sea surface temperature anomaly, Western Indonesian Maritime Continent (IMC), Convective activity