Large-scale circulation features associated with the heat wave over Northeast China in summer 2018

In late July and early August 2018, Northeast China suffered from extremely high temperatures, with the maxium temperature anomaly exceeding 6 degrees C. In this study, the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP-NCAR reanalysis data. The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China, and the related downward motions were directly responsible for the extreme high-temperature anomalies. The northwestward shift of the western Pacific subtropical high (WPSH) and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China. In addition, an anomalous Pacific-Japan pattern in the lower troposphere led to the northwestward shift of the WPSH, jointly favoring the anomalous geopotential height over Northeast China. Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes, respectively, and converged over Northeast China, leading to the enhancement of the geopotential height anomalies.