Hazard assessment of extreme heat during summer maize growing season in Haihe Plain, China

Abstract

The characteristics of extreme heat events (EHE) are changing under global warming. A comprehensive assessment of extreme heat hazards is important for a better understanding of extreme heat distribution and agricultural mitigation planning. In the present study, an extreme heat hazard assessment model is defined by its probability and severity. Continuous days and accumulative temperatures are used to describe the severity of EHE. Daily maximum temperature data from 26 stations in the Haihe Plain during 1960–2019 are used to identify EHE during the summer maize growing seasons. This region is the main summer maize planting area and suffers from numerous EHE. Copula functions are used to estimate the joint probability distributions of continuous days and the accumulative temperature of EHE. The fitted probabilities are then used in the hazard assessment model. The results reveal that the most severe extreme heat hazard areas are found in the western Haihe Plain, the frequency, average continuous days and accumulative temperature of EHE are the largest in this area. The extreme heat hazards are decreased to the northeastern coast area. Annual variations in extreme heat hazard show two change points near 1968 and 1996 that divide the research period into three main stages: higher, lower, and higher extreme heat hazard stage. These findings provide a comprehensive view of extreme heat over the Haihe Plain, which can be used for better extreme heat management and agriculture planning.