TITLE:
A Synthetic Study of the Position Difference of the Southern Branch Trough of the Qinghai-Tibet Plateau Based on Objective Identification
AUTHORS:
Ke Li, Shunwu Zhou, Xia Shi, Siyuan Chen, Qianqian Song
KEYWORDS:
The SBT, Winter, Spring, Full-Type Vertical Vorticity Inclination Equation, Dynamic Characteristics, Thermodynamic Characteristics, T-N Wave Activity Flux
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.3,
March
30,
2021
ABSTRACT: The southern branch trough (SBT) mainly appears in the winter half year (November to May of the following year), using the 4 times daily NCEP/NCAR re-analysis data nearly 41 years (1979-2019) to analyze the differences of the SBT distribution of spatial location, frequency in winter and spring, then selects the “eastern type” and “western type” of the 10 most typical SBT, using simplified vertical vorticity tendency equation, using simplified vertical vorticity tendency equation to diagnosis of the SBT in power, heat, water vapor and wave energy in different positions. The results show that: 1) The location of the SBT is more eastward in winter, and more westward in spring. 2) The diagnosis results of the vorticity equation show that the vorticity of the southern branch of the “western type” is mainly contributed by advection term; the vorticity of the “eastern type” south branch is mainly contributed by the non-adiabatic heating term. 3) The SBT of the “eastern type” has more obvious vorticity advection than the southern branch of the “western type”, and the dynamic action is stronger. The “western type” SBT has stronger Q1, specific humidity advection and water vapor flux than the “eastern type” SBT, which is greatly affected by thermal action and water vapor. When the “eastern type” and “western type” SBT occur, the T-N wave activity flux appears obvious abnormal energy fluctuation propagation.