Investigating Compound Drought and Hot Extreme Events in Southeast Asia Through Copula Analysis

ABSTRACT The concurrent occurrences of drought and extreme heat events, such as heatwaves, present substantial threats to human health and ecosystems. This study delves into a thorough examination of the collective impacts of drought and extreme heat events in Southeast Asia (SEA) over the past 83 years (1941–2023). Two primary definitions guided the investigation: Compound Drought and Heatwave Events (CDHW) and Compound Hot Droughts (CHD). The Wet‐Bulb Globe Temperature (WBGT) was employed to define heatwaves and extreme hot events, while the Standardised Precipitation Evapotranspiration Index (SPEI) was used for drought definition. In addition, the study explored the impact of linear detrending on copula fitting, assessing its effects. The findings of the study consistently revealed a strong positive correlation between drought and heatwaves in CDHW. On the other hand, CHD exhibited varied correlation patterns across regions. Furthermore, the study highlighted that linear detrending had a lower sensitivity in CDHW compared to CHD. The analysis uncovered significant regional disparities in the joint return period ranking of compound events, stemming from diverse copula analysis approaches. Particularly in non‐continental SEA, notably in some regions like Sumatra Island, a noteworthy distinction between CDHW and CHD emerged, indicating the limited applicability of CHD in scenarios with stringent concurrence of compound events. These insights provide valuable assistance to the research community, aiding in the discernment of the distinctions between CDHW and CHD in drought and heat‐event assessment.