Quantifying Extreme Climate Phenomena: A Case Study of Drought in Africa and Moist Heatwaves in Southeast Asia

Extreme climate events, such as droughts and heat waves, significantly impact ecosystems and human societies. However, accurately quantifying these extremes requires understanding their distinct characteristics and regional variations and facing sources of uncertainties. This study addresses this challenge through an introduction analysis of case studies focusing on two different regions: drought in Africa and moist heatwave in Southeast Asia. Over the African continent, we approach the study by the Standardized Precipitation-Evapotranspiration Index (SPEI), Vapor Pressure Deficit (VPD), and relationship with soil moisture to analyze drought intensity, frequency, and duration. Projections indicate a shift from wet to dry conditions around 2085, with future RCP8.5 scenarios suggesting a reduction in the intensity and frequency of "Extreme" and "Very" dry conditions compared to historical periods. GCMs suggest a higher likelihood of droughts than RCMs for 2051-2100. Notably, VPD shows significant variability in the Sahel and Southern Africa, with future projections indicating a stronger relationship between soil moisture and VPD during summer. In the case of Southeast Asia, particularly Southern Vietnam and Cambodia, it is identified as a hotspot for moist heat waves in a warming climate. We use JRA55 and BCSD downscaling techniques to investigate the trends with further formation mechanisms, physical understanding, and future projections of these heatwaves. The study also examines the Clausius-Clapeyron relationship to understand how changes in temperature and humidity affect the intensity and frequency of these events and quantify compound events such as moist heat waves and extreme precipitation. By improving our comprehension of extreme climate dynamics and their regional manifestations, we hope to provide valuable insights for policymakers and researchers, guiding future efforts to mitigate and adapt to climate change impacts.