Role of North Atlantic warming in the extremely hot summer of 2023 in North China

Abstract A deadly heatwave hit North China in the summer of 2023, causing severe damage to human health and public infrastructure. However, the underlying physical mechanism is still unknown completely. In this study, we explore the causative role of anomalous sea surface temperatures in three oceans using observation and reanalysis data, as well as partial regression and correlation methods. This heatwave exhibited the longest maximum duration of the past 50 years. According to the probability density function, the maximum temperature also reached an unprecedented high. A long-lived anticyclone dominated North China, causing persistent downward motion and adiabatic heating, enabling the heatwave to form and continue for more than 20 days. The Indian, Pacific, and North Atlantic oceans all experienced extreme warming. However, our results indicate that North Atlantic warming played a decisive role in the occurrence of this heatwave by exciting a Rossby wave train that propagated eastward, generating the long-lived anomalous anticyclone and inducing heatwaves. In comparison, the other two oceans exhibited weak or negative contributions to the heatwave. As the North Atlantic shows an obvious warming trend with increasing global warming, more attention should be paid to its relationship with heatwaves in North China.