Numerical Simulation on the Formation of Mesoscale Vortex in Col Field |
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| Authors: | Yongqiang Jiang Yuan Wang |
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| Institution: | 1. Key Laboratory of Mesoscale Severe Weather/Ministry of Education of China,and School of Atmospheric Sciences, Nanjing University, Nanjing 210093;Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101
2. Key Laboratory of Mesoscale Severe Weather/Ministry of Education of China,and School of Atmospheric Sciences, Nanjing University, Nanjing 210093 |
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| Abstract: | There exist typically two kinds of low-level col fields over the middle and lower reaches of the Yangtze River of China during
summer. One is associated with the mesoscale vortex embedded in the Meiyu front; the other is related to tropical cyclones
making landfall over eastern or southern China. The first one is the focus of this study. The meso-β scale vortex (MβV) causing heavy rainfall usually forms in a col field or within a shear line associated with the mesoscale low-level jet
(mLLJ). The MβV, triggered by mesoscale wind perturbation in a col field, is simulated by using a three-dimensional η-coordinate mesoscale model. This col field represents the circumstance of the “98.7” heavy rainfall event over eastern Hubei
Province. The results show that the MβV triggered by wind perturbation was weak and maintained only several hours if the latent heat feedback was switched off.
The wind perturbation also weakened rapidly. However, when the latent heat feedback was included, precipitation became more
intense and the mLLJ and MβV quickly developed. The MβV maintained quasi-stationary during its life cycle under the stable col field. |
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| Keywords: | col field mesoscale vortex mesoscale low-level jet wind perturbation |
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