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

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. Heat waves adversely impact all sectors of human societies such as public health and economy. Global warming is expected to increase the frequency and severity of extreme temperatures and heatwaves worldwide. Although heatwave has been extensively investigated, little studies focused on characterizing and modeling a heatwave threshold. Additionally, investigations on the variation in the frequency of heatwaves as well as evaluating the main drivers of heatwaves are generally lacking. This study proposes probabilistic framework to explore the heatwave events with different duration by applying appropriate thresholds for each specific site. Our study outlines a novel approach that allows to define the frequency of heatwave and apply time-varying statistical distributions with parameters conditional on covariates representing time and teleconnection models to account for the temporal trend caused by climate variability and change. The results indicate significant increases in heat waves across the Iran during the last four decades. A new probabilistic framework explores the heatwaves non-stationarity and their spatial coverageNon-stationary models confirm the temporal evolution of heatwaves due to global warming during 1977-2019 over IranResults suggest a substantial increase in the heatwave heating rate across Iran during the last four decades

Automated summary

This study develops a probabilistic framework to explore heatwave events and applies it to climate change research in Iran. The results show a significant increase in heatwave hazard across Iran, with shorter heatwaves being more intensified.