Exploring ENSO and IOD effects on Southern Indian Ocean cyclones from 1970 to 2022

The number of tropical cyclones (TCs) originating from the southern Indian Ocean continues to increase, significantly impacting Java and Sumatra.However, this region's research on tropical cyclones still needs to be improved compared to other regions.This study aims to explore El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) Effects on Southern Indian Ocean Cyclones from 1970 to 2022.Trends in cyclone occurrence were evaluated using the Mann-Kendall nonparametric statistical test and Sen's slope estimation.The analysis showed that the highest number of daily TCs in ENSO was formed during the neutral phase in all categories.The number of annual TCs in categories 1-2 experienced a decreasing trend during ENSO phases, but TCs in categories 3-5 only decreased in the El Nino phase.In addition, the highest daily amount of IOD is formed in the neutral and positive phases for TC category 1-2, but for TC category 3-5, it is highest in the neutral phase.The annual number of TCs in categories 1-2 shows a significant downward trend in all IOD phases.However, TCs in categories 3-5 only decreased in certain phases, with an increase observed in the neutral phase.In summary, this study highlights the different influences of ENSO and IOD on different categories of tropical cyclones in the southern Indian Ocean.These findings confirm the complex interactions between climate oscillations and tropical cyclone occurrence and emphasize the importance of considering various climatic factors to understand and forecast these phenomena.As such, the results of this study make a valuable contribution to developing our understanding of tropical cyclone dynamics in the relevant region.