资源环境科技发展态势分析平台

Based on the Final operational global analysis data from the Global Forecasting System of the National Centers for Environment Prediction and the radiosonde data, the development and eastward movement mechanisms of 15 Tibetan Plateau vortices (TPVs) after they move off the plateau are investigated. The results show that the convergence to the east of the TPVs at 500hPa, the divergence associated with the westerly jet stream at 200hPa, as well as the corresponding ascending motion provide favorable conditions for the development and eastward movement of the TPVs. The spatial structures of the atmospheric apparent heat source (Q(1)) and the apparent moisture sink (Q(2)) are studied, showing that the heating centers of Q(1) at 400hPa mainly sourced from the condensation latent heat are beneficial to the eastward movement of the TPVs, while the horizontal distribution of Q(1) at 500hPa goes against that. The development and eastward movement mechanisms of the TPVs after they move off the plateau are further discussed through diagnosing the potential vorticity (PV) tendency equation. It is revealed that the horizontal PV flux convergence to the east of the TPVs related to the convergence at 500hPa plays as the dominant role, exerting positive contribution to the PV tendency. Meanwhile, the heating fields induce feeble PV tendency, indicating more important effect of the dynamic factor. The development and eastward movement mechanisms of the TPVs after they move off the plateau are different from those before the TPVs move off, and the dynamic effect is vital in the former stage while the effect of Q(1) is revealed as the dominant influencing factor in the latter.