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<p>The classification of Northeast China Cold Vortex (NCCV) activity paths provides a fundamental framework for understanding their characteristics, but the formation mechanisms of NCCVs with distinct paths remain insufficiently explored. Based on the 6-hourly ERA5 reanalysis data from 1991 to 2022, this study develops an objective identification method for NCCVs during May to July, classifies their activity paths using the K-means clustering method, and investigates their atmospheric circulation configurations and responses to the background flow. The main conclusions are as follows: (1) The NCCV activity paths can be classified into four types: the southern-positioned type (type A) originating over the Mongolian Plateau and moving eastward into the ocean; the northwestward-activity type (type B) primarily occurring between the Greater and Lesser Khingan Mountains with limited propagation distances; the northeastward-activity type (type C) concentrated to east of Northeast China (NEC) and the irregular type (type D) characterized by sparse occurrence and scattered distribution. (2) Differences in the activity paths of NCCVs manifest in the atmospheric circulation features and evolutionary characteristics. Type A and type B NCCVs mainly affect the southern and northern NEC region, respectively, while type C NCCVs impact east of Heilongjiang Province. (3) The background flow modulates wave propagation and eddy generation by regulating Rossby wave energy accumulation and dispersion in different regions. Variations in the double-jet structure’s position, along with differences in the location of zonal wind deceleration and acceleration regions and the intensity of zonal wind anomaly, jointly facilitate local baroclinic eddies formation at different locations, thereby leading to diverse activity paths of NCCVs.</p>

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Activity of summer Northeast China cold vortex with different paths and its response to background flow

  • 期刊论文

  • 发表日期：

    2025年8月31日

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  • Xiaowen Zhao,
  • Lijuan Wang,
  • Zhaoyong Guan

摘要

The classification of Northeast China Cold Vortex (NCCV) activity paths provides a fundamental framework for understanding their characteristics, but the formation mechanisms of NCCVs with distinct paths remain insufficiently explored. Based on the 6-hourly ERA5 reanalysis data from 1991 to 2022, this study develops an objective identification method for NCCVs during May to July, classifies their activity paths using the K-means clustering method, and investigates their atmospheric circulation configurations and responses to the background flow. The main conclusions are as follows: (1) The NCCV activity paths can be classified into four types: the southern-positioned type (type A) originating over the Mongolian Plateau and moving eastward into the ocean; the northwestward-activity type (type B) primarily occurring between the Greater and Lesser Khingan Mountains with limited propagation distances; the northeastward-activity type (type C) concentrated to east of Northeast China (NEC) and the irregular type (type D) characterized by sparse occurrence and scattered distribution. (2) Differences in the activity paths of NCCVs manifest in the atmospheric circulation features and evolutionary characteristics. Type A and type B NCCVs mainly affect the southern and northern NEC region, respectively, while type C NCCVs impact east of Heilongjiang Province. (3) The background flow modulates wave propagation and eddy generation by regulating Rossby wave energy accumulation and dispersion in different regions. Variations in the double-jet structure’s position, along with differences in the location of zonal wind deceleration and acceleration regions and the intensity of zonal wind anomaly, jointly facilitate local baroclinic eddies formation at different locations, thereby leading to diverse activity paths of NCCVs.