Observed Trends in Various Aspects of Compound Heat Waves across China from 1961 to 2015

Based on combined thresholds of daily maximum and minimum temperatures, a compound heat wave is defined, and then changes in multiple aspects of such heat waves in China are estimated between 1961 and 2015. Our results intriguingly indicate that severe compound heat waves in northern China are characterized by excessively high intensity within short duration, while long duration determines great disaster-causing potential of severe events in the south. In the past few decades, large areas of China have experienced longer, stronger, and more frequent compound heat waves. Northern China has witnessed dramatic intensity increases, with a maximum amplification over 5°C decade^–1; while remarkable lengthening in duration has been mostly recorded in the south, with a maximum trend over 1 day decade^–1. The spatial extent affected by compound heat waves has significantly expanded since the 1960s, with the largest expanding rate over 6% decade^–1 detected in North China and Northeast China. These systematic assessments serve to deepen our understanding of observed changes in compound heat waves across China, and may further shed some light on future adaptations and mitigations against an increasingly warming climate.