The impacts of winter snow cover of central Asia on the northeastern China cold vortex in succeeding spring

Abstract

Abstract During the boreal spring, extratropical cyclones in East Asia exhibit the highest frequency of occurrence in northeastern China. These cyclones are characterized by a distinct cold core, which is commonly referred to as the northeastern China cold vortex (NCCV), and most of NCCV events are usually accompanied by complex and hazardous weather, significantly impacting the regional climate in northeastern China. In this study, an automatic algorithm was employed to identify spring NCCVs from 1979 to 2013 using ERA-Interim reanalysis dataset, and a notable annual periodicity of 3–4 years was observed based on the defined spring NCCV intensity index (NCCVI). Through the analysis of anomalous strong/weak NCCVI years, it was found that the consistent heating (cooling) in the middle and lower troposphere of central Asia (northeastern China), along with a corresponding negative anomaly of geopotential height, as well as the enhanced cyclonic circulation in northeastern China, all contribute to the intensification and maintenance of NCCV activities. Furthermore, the winter snow cover in central Asia plays a vital role in local atmospheric heating and is associated with anomalous quasi-stationary Rossby waves that propagate eastward into northeastern China. The thermal forcing, caused by preceding (DJF) snow cover anomalies of central Asia, and associated anomalous Rossby wave trains was also replicated well by snow cover anomalies driven sensitive experiment.