Changed relationship between compound dry-hot events and ENSO at the global scale

Abstract

Compound dry-hot events (CDHEs) have received ample attention recently due to their profound impacts on water resources, crop yields, and ecosystems. The occurrence of CDHEs in large regions across the globe can be driven by teleconnection patterns, such as El Niño-Southern Oscillation (ENSO). Previous studies have revealed the linkage between ENSO and CDHEs across the globe. However, assessments of potential changes in the response of CDHEs to ENSO are still lacking. In this study, we explore changes in the relationship between ENSO and CDHEs for the period 1901–2010 over global land areas. We find the ENSO-CDHEs relationship strengthens in western South America (WSA), southern Africa (SAF), and southern Asia (SAS) and weakens in eastern Australia (EAU). The changed ENSO-CDHEs relationship induces variations in the likelihood of CDHEs occurring during El Niño (and La Niña) events. From 1901–1955 to the recent period 1956–2010, the probability of the occurrence of CDHEs during El Niño increases from 0.27 (0.47, 0.40) to 0.58 (0.53, 0.50) in WSA (SAF, SAS) and decreases from 0.60 to 0.47 in EAU. In addition, the prediction skills of CDHEs based on ENSO also differ for different periods in these regions owing to the changed ENSO-CDHEs relationship. The findings of this study provide valuable insights for understanding the risks of CDHEs and early warning of their occurrences.