Extreme heat event over Northwest China driven by Silk Road Pattern teleconnection and its possible mechanism

Abstract

Under the background of global warming, heat wave events have become significantly frequent and have received increasing attention. Northwest China is located in the drylands of central Eurasia, where the climate and ecological environment are more vulnerable to global warming than in other parts of the world. Over the past few decades, the frequency of heat waves in Northwest China has increased significantly, and its causes remain unclear. We found that the heat events in Northwest China were closely related to the Silk Road Pattern teleconnection (SRP), and the strongly positive phase of SRP frequently corresponded to the occurrence of heat waves. Furthermore, the wave source of SRP was determined by the Linear baroclinic model to be located in the North Atlantic Ocean. We then selected an extreme heat event over Northwest China in 2021 as a typical case to discuss the possible mechanism. The regressed circulation fields to daily SRP were highly consistent with the anomalies that occurred during July 9–22, 2021, indicating that the diurnal propagation of SRP modulated the circulation anomaly related to the heat wave event and that diabatic heating influenced by SRP was the primary factor to the thermal low over Northwest China. Diabatic heating was strengthened in the lower troposphere due to the enhancement of downward shortwave radiation and surface sensible heat flux accompanied by strong descending motions and cloud cover reduction by an SRP-guided anticyclone over Northwest China. This study enhances the understanding and certainty regarding large-scale circulation effects on local temperature anomalies in middle latitudes.