ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 43 Issue 11 > 2017,43(11):1326-1338. DOI:10.7519/j.issn.1000-0526.2017.11.002 Prev Next
Diagnostic Analysis on the Energy of a Mesoscale Convective Vortex in Enhancing Stage
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Abstract:
Based on the fourtimes daily CFSR global reanalysis data and the hourly observed national base station precipitation in the Central China region, we focused on one mesoscale convective vortex (MCV) weather process that occurred in Central China on 1 June 2015, and studied the characteristics of energy distribution and the mechanism that impacted the MCV during the enhancement phase by using the WRF simulation and energy diagnosis method. The results showed that the MCV was born in the central part of Hubei Province, then it moved towards Dabie Mountain in northeast of Hubei Province with enhancing intensity of MCV. By analyzing the precipitation distribution characteristics during the vortex enhancing stage, we found that the precipitation mainly focused on three regions at the early stage, then evolved into the distribution of zonal pattern. By analyzing meteorological conditions corresponding to the vortex enhancing stage, we found that latent heat caused by precipitation, the warm and wet southwest flow transport in the lower troposphere, the cold and dry air intrusion in the midlevel and a sharp increase of CAPE value were favorable for the enhancement of MCV intensity. On one hand, the convergence flow was strengthening in MCV peripheral section while the vortex was developing, resulting in the increase of perturbation kinetic energy. On the other hand, latent heat of condensation generated by precipitation resulted in the increase of perturbation available potential energy in middle level of troposphere. Then, the available potential energy was transferred upward by vertical air flow, hence it caused the enhancement of available potential energy in upper level of troposphere. With the method of calculating budget of the above two kinds of energy, we found that the energy producing items in the MCV enhancing stage were the conversion between perturbation available potential energy and perturbation kinetic energy which was triggered by pressure change between inside and outside of the MCV system, the effect of viscous force produced by basic air flow in different levels of troposphere, the conversion between zonal mean available potential energy and the perturbation kinetic energy caused by latent heat release as well as the input of perturbation kinetic energy from the outside of MCV system. However, the conversion between perturbation available potential energy and perturbation kinetic energy was the most contributable item for the development of MCV. By further analyzing its spatial distribution characteristics, we concluded that in the lower level and upper levels of troposphere, the forward conversion was propitious to strengthen the convergence and divergence flow, but in middlelevel and upperlevel troposphere, the reverse conversion was propitious to store the energy to satisfy the need of maintenance of vortex after it developed into maturity.
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P458
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