Role of tropical cyclone heat potential in the intensification of super cyclone Amphan and its impact on dissolved oxygen dynamics in the Bay of Bengal

Super Cyclone Amphan, the only super cyclone recorded in the Bay of Bengal (BoB) in the 21st century, caused 128 fatalities and $14.3 billion in property damages. Despite its impact, the cyclone’s intensification mechanisms and effects on oceanic geochemical conditions, including marine productivity, remain poorly studied and not well understood. The primary purpose of this research is to examine the role of Tropical Cyclone Heat Potential (TCHP) in Amphan’s formation and intensification, and its influence on dissolved oxygen (DO) concentrations. Using satellite remote sensing data, we analyzed TCHP variations across the region during the cyclone’s development. The findings reveal that high TCHP values and a deeper 26 °C isotherm was crucial in driving Amphan’s rapid intensification into a category 5 storm. Areas with TCHP above 160 kJ cm⁻² in the central and northern Bay provided the necessary subsurface heat. The cyclone also triggered significant upwelling, reducing DO levels to 196 mmol m⁻³. Empirical Orthogonal Function (EOF) analysis revealed that the first principal component explained 70% of the variance, highlighting strong co-variability among TCHP, sea-surface temperature (SST), depth of 26 °C isotherm (D₂₆), and DO. Correlation analysis showed strong positive relationships between TCHP and DO (0.970), TCHP and sea-SST (0.960), and a negative correlation with wind speed (-0.980). These findings highlight TCHP’s importance in cyclone forecasting and underscore the need to better understand cyclone-driven ecosystem impacts in the BoB for improved climate and coastal resilience.