Heatwave Duration and Heating Rate in a Non-Stationary Climate: Spatiotemporal Pattern and Key Drivers

Abstract

Heatwaves have had adverse affects on human life, ecosystems, and society. Global warming is expected to heighten the characteristics of heatwaves such as severity, duration, and frequency. Therefore, understanding the evolution of heatwaves is a central issue in climate change research with high relevance for society. Establishing a proper threshold for issuing a heatwave can be one of the most important issues in heatwaves studies, however, fewer studies focused on characterizing and modeling a heatwave threshold according to non-stationary behavior, local geographic and physiographic characteristics. We have developed an applicable probabilistic framework to explore the heatwave events with different durations by applying appropriate thresholds. In this study, the proposed framework was applied to define the nonstationary frequency analysis of heatwaves models to account for the temporal trend caused by climate variability and change across Iran. The results showed that shorter heatwaves odds have been intensified more over Iran while longer heatwaves have not changed substantially. We find a substantial increase in heatwave hazard across Iran with a 40-year available daily record, collectively from 1977 to 2019. The spatial distribution of the best non-stationary models confirms the temporal evolution of heatwaves features due to global warming over Iran.