Spatiotemporal variations of the global compound heat wave and the drivers of its spatial heterogeneity

Compound heat wave (CompoundHW), a specific extreme heat event sustains from daytime to nighttime, has adverse impact on human health and natural ecosystems. However, the analysis of temporal change and driving factors of spatial distribution of CompoundHW on a global scale is limited. In this study, the temporal and spatial variations of global CompoundHW were investigated based on three datasets. The effects of climatic factor, underlying surface factors (Dem, dominant vegetation type and albedo), climate change factors, and socioeconomic factors on the spatial distribution of raw, variability-contributed and warming-devoted CompoundHW severity were assessed using the Geodetector method. Results showed increasing trends in the days, frequency, cumulative heat and occurrence proportion of global average CompoundHW. Spatially, the middle and high latitudes of the North Hemisphere showed more intense CompoundHW and most regions exhibited increases in CompoundHW metrics in the second half of 1983–2012. The climatic factor exhibited highest effect on the spatial distribution of CompoundHW metrics, followed by dominant vegetation type and climate change factors, with the corresponding explanatory power about 60%, 20% and 10%. The socioeconomic factors showed the lowest effects, but enhanced effects when interacting with other factors. The climate change factors showed higher effect on the spatial pattern of warming-devoted CompoundHW than variability-contributed CompouondHW, with explanatory power of 30% and less than 10% respectively. Additionally, the climatic factor and climate change factors played comparable strength in influencing the spatial differences of warming-devoted CompoundHW metrics. This work helps the regionalized development of adaptation and mitigation methods by outlining the characteristics and factors that influence the spatial distribution of global CompoundHW.