Project
Future Projection of Tropical Cyclones in Southern Indonesia Waters
This research project aims to unlock the secrets of tropical cyclone formation near islands in the Indonesian waters. This region's unique geography, characterized by complex coastlines, towering volcanoes, and its location between two major oceans, presents specific challenges for accurate cyclone prediction. These features can make it challenging to predict when and how cyclones will form.
The research focuses on several key factors that influence cyclone genesis, including local convection, called Madden-Julian Oscillation (MJO), Kelvin waves, and Rossby waves that travel around the atmosphere around the world. The project aims to understand how the MJO interacts with the local weather patterns and island topography to facilitate or inhibit cyclone formation.
The challenge is further compounded by climate change, which is expected to raise sea levels and warm ocean temperatures, potentially leading to more intense and unpredictable cyclones. Therefore, the research also examines how climate change might affect cyclone activity in the future.
The complexity of TC genesis is further exemplified by the formation of tropical cyclones Dahlia and Cempaka in late 2017 near Indonesia. These cyclones likely developed due to a combination of factors, including warm sea surface temperatures, low vertical wind shear, and the influence of the Australian monsoon trough (Emanuel et al., 2004; Tao & Zhang, 2014). Recent Tropical Cyclones Cempaka and Dahlia formed because of warm ocean waters, which give the storms energy to grow. However it remains an open question how TC properties will change with climate change. This study will contribute to unraveling this future TC evolution.
A tropical cyclone is a synoptic-scale, non-frontal low-pressure system that develops over warm waters with convective flotation areas and a maximum wind speed of > 34 knots in more than half of the area surrounding the centre. It lasts for at least six hours. Strong winds, storm surge, and heavy rain are the main causes of damage from tropical storms. Around two-thirds of tropical cyclone generation occurs in the Northern Hemisphere. Based on data from 1968 to 1989, the average number of tropical cyclones that developed in the Northern (Southern) Hemisphere annually was 57.3 (26.3) (Azgha & Mukminan, 2019).
Using data spanning from 1964 to 2005 for tropical cyclone events in the Southeast Indian Ocean and from 1951 to 2006 for the Northwest Pacific region, the Indonesian Meteorological, Climatological, and Geophysics Agency (BMKG) has analyzed the frequency of tropical cyclones near Indonesia, specifically within the coordinates of 90° to 150° East and 30° North to 30° South. The findings reveal that in the southern part of this region, February is the peak month for TC occurrences, accounting for 23% of events in a single month. This is closely followed by March at 22%, January at 21%, December at 14%, and April at 11%. In contrast, the northern region near Indonesia exhibits a different pattern, with data spanning 56 years indicating that August is the month with the highest incidence of TCs, accounting for 20% of total occurrences. September follows with 18%, while July and October each contribute 15% to the cyclone count. These trends highlight significant seasonal variations in tropical cyclone activity in the Indonesian region.
From 1983 to 2017, 51 tropical cyclones were recorded in southern Indonesia, primarily between November and April. These cyclones typically have a lifespan of around 7 to 8 days, indicating a relatively consistent duration for tropical storm systems in this region (Mulyana et al., 2018). Interestingly, despite Indonesia's geographic position near the equator—an area less conducive to tropical cyclone formation due to a relatively weak Coriolis force—, the data reveal that some cyclones form or migrate toward the southern Indonesian waters, especially in the latitudinal range of 0°–10°S. Notably, nine cyclones during this period have either developed close to or moved into Indonesian territory, illustrating that while the region is not a primary birthplace for these storms, it is still affected by their trajectories. The proximity of certain cyclones, such as Dahlia and Cempaka in 2017, underscores their potential to significantly influence local weather patterns, heavy rainfall, and flooding events despite the relatively high central pressure values compared to cyclones in higher latitudes. This pattern highlights the region's susceptibility to the impacts of tropical cyclones originating in adjacent oceanic areas, particularly the Indian Ocean. It highlights the importance of monitoring their paths and intensities for disaster preparedness.
The complexity of TC genesis is further exemplified by the formation of tropical cyclones Dahlia and Cempaka in late 2017 near Indonesia. These cyclones likely developed due to a combination of factors, including warm sea surface temperatures, low vertical wind shear, and the influence of the Australian monsoon trough (Emanuel et al., 2004; Tao & Zhang, 2014). Tropical Cyclones Cempaka and Dahlia formed because of warm ocean waters, which give the storms energy to grow. Cempaka originated in the southern part of Java and was influenced by nearby volcanic ash from Mount Agung in Bali, which facilitated its westward movement. Dahlia began about 1,500 km west of Jakarta as a small storm in the Indian Ocean. This TC strengthened as it moved over the warm waters, with wind speeds increasing and the pressure dropping to 985 hPa. Both cyclones had typical features, like a low-pressure centre and strong winds, and they expanded as they absorbed energy from the warm ocean before weakening when they moved over calmer waters or land (Windupranata et al., 2019)
The genesis of TCs in the Indonesian waters, particularly low latitudes near the islands, presents a complex meteorological challenge. While general conditions conducive to TC formation are understood, the specific interplay of these factors and the relative importance of each in the region remain areas of active research. Existing literature highlights the influence of the Madden-Julian Oscillation (MJO) and equatorial Rossby waves as potential drivers of TC genesis in this broader region. For example, research on TC Seroja (April 2021) emphasizes the crucial role of MJO and equatorial wave interactions in enhancing cyclogenesis near Timor Island, highlighting the importance of these atmospheric phenomena in the broader East Nusa Tenggara region (Latos et al., 2023).