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Keywords:

  • subtropical jet;
  • polar front jet;
  • concurrent variation;
  • snowstorm

Abstract

[1] The concurrent variation features between the East Asian subtropical jet and polar front jet were investigated during persistent snowstorm period in 2007/2008 winter over southern China. The East Asian subtropical jet was divided into two parts: (1) the plateau jet, located along the southern side of the Tibetan Plateau, and (2) the ocean jet, situated at the southeastern Japan Island. The concurrent intensity variation among the polar front jet, plateau jet, and ocean jet and the associated atmospheric anomalous signals were examined. A possible mechanism for concurrent variation among the three jets was also investigated from a perspective of synoptic-scale transient eddy activities (STEA). The enhanced plateau jet was simultaneously correlated with the weakened polar front jet, while the variation of the ocean jet lagged the variation of the plateau jet (polar front jet) about 5 days. The concurrent variation between the plateau jet and the polar front jet acted as an important bridge that linked the snowstorm to the atmospheric anomalous signals associated with the cold and warm air activities. Due to the opposite trends of STEA variation over the southern and northern sides of the Tibetan Plateau, the plateau jet and the polar front jet exhibited a significant concurrent variation feature. The STEA anomalies over the plateau jet and polar front jet regions propagated downstream to the East Asian coast as a wave train along the southern and northern sides of the Tibetan Plateau, respectively, resulting in a 5 day lag variation relationship between the ocean jet and the plateau jet (polar front jet).