Comparison of extreme heatwaves in Southern China in August 2022 and 2024

In August 2022 and 2024, Southern China experienced unprecedented heatwaves. Using ERA5 reanalysis data, we conducted a comparative analysis of the similarities and differences between these two extreme heatwaves. Our findings reveal that while the 2024 heatwave was less intense than the one in 2022, it was more concentrated in late August, unlike the prolonged heatwave in 2022, which spanned the entire month. Despite these variations in intensity and duration, both heatwaves were driven by a common atmospheric mechanism: anomalous easterly winds resulted in subsidence and significant temperature anomalies across Southern China. These easterly winds were closely associated with an anticyclone anomaly over the region, influenced by an upstream wave train from Europe. Crucially, warm sea surface temperature (SST) anomalies in the Barents Sea played a vital role in sustaining and forming this wave train. To further validate this mechanism, we conducted a regression analysis using historical data from 1979 to 2024, confirming its broad applicability in explaining heatwaves in Southern China, including those of shorter durations like the 2024 event. This study significantly advances our understanding of heatwave dynamics in Southern China and offers novel insights that can improve future predictive capabilities.