Causes Analysis of Heatwave Events in North China in June, 2023

On June 14—17 and 21—24, 2023, the North China experienced two of the strongest extremely high events in nearly 40 years, seriously affecting people′s production and life. This article uses reanalysis data to study these two extremely high heatwaves. The results indicate that the heatwaves in North China in June 2023 are both related to the high pressure ridge that moved eastward from the upper reaches of the Eurasian continent. The high pressure ridge was strengthened during the eastward movement due to the influence of the flux of the two wave trains from the north and south. Comparing the contributions of different physical processes to the temperature in North China, it was found that anomalous diabatic heating played a positive role in the formation of both heatwave events, anomalous adiabatic heating had a greater warming effect in the second heatwaves, and anomalous horizontal advection mainly played a cooling role. The wave trains over the Eurasian continent are related to two parts: the southern one mainly propagates eastward along the subtropical zone in the eastern Atlantic Ocean, while the northern one propagates southeastward from Northern Europe. There were anomalous upward movements and anomalous precipitation in the eastern Atlantic and central European during June 4—6 and 17—18, respectively. The results of the LBM demonstrate that the anomalous heat source generated by the latent heat caused by precipitation can stimulate the circulation pattern favorable to heatwaves in North China over the Eurasian continent.