MOIST POTENTIAL VORTICITY DIAGNOSIS OF A MEIYU FRONTAL HEAVY RAIN PROCESS SIMULATION DURING SUMMER, 1991 |
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Authors: | Zhang Jing Wei Tongjian and Zhang Xiangdong |
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Institution: | Department of Geophysics, Peking University, Beijing 100871;Department of Atmospheric Sciences, Nanjing University, Nanjing 210093;Chinese Academy of Meteorological Sciences, Beijing 100081 |
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Abstract: | In this paper,the heavy rain process from June 30 to July 2,1991,has been simulated by MM4.and three-dimensional moist potential vorticity distribution of the simulation results has been calculated.It is shown that moist potential vorticity is an important physical variable to reveal heavy rain structure and dynamic mechanisms.Negative moist potential vorticity corresponds to the Meiyu front-wind shear line system and the negative center corresponds to the heavy rain center.Negative moist potential vorticity mainly attributes to the effects of meridional baroclinic term and convective unstable term.The former is favourable to the maintenance of zonal precipitation and the latter is the mechanism of the heavy rain center propagating along the rain belt.The heavy rain is contributed by the cooperative effects of conditional convective instability,baroclinic instability and upper air inertial instability. |
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Keywords: | moist potential vorticity heavy rain Meiyu mesoscale model 4(MM4) |
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