关键词: 西南低空急流, 台风暴雨, 显热能, 潜热能, 动能转换

Abstract:

This paper focused on the energy variations in the typhoon center and storm regions. The temporal and spatial distributions of apparent energy, latent energy and kinetic energy were investigated in the process of the typhoon’ s transition by means of energy analysis. The variations of the energies increase in the process of abrupt enhancement of remote precipitation and the long time maintenance of typhoon intensity were studied quantitatively. On the other hand, the source of the energy increase was discussed quantitatively in the typhoon center and storm regions. The main results were as follows: (1) Though the magnitude of latent heat energy was less than that of apparent heat energy, the advection of latent heat energy was stronger than that of apparent heat energy. The contribution to typhoon certre and storm regions made by latent heat energy was larger than that made by apparent heat energy. (2) A deep latent heat energy layer was in the lower-middle troposphere over the rainstorm regions when the remote typhoon rainstorm occurred. The released condensation latent heat was beneficial to the occurrence of the rainstorm. The low value region of apparent heat energy and air temperature in the lower level troposphere was favourable for the development of baroclinic instability potential energy and played a role in the enhancement of the precipitation. (3) The main reasons of long time maintenance of the typhoon intensity was due to the extra regional energy supplement. The southwest wind jet was the main way to supplement typhoon energy by apparent heat energy and latent heat energy. The increment of latent heat energy was much larger than that of apparent heat energy. (4) The long time maintenance of typhoon intensity strengthened the southwest low level jet. At the same time, the apparent energy advection and latent heat advection in the lower level troposphere were also strengthened in the rainstorm area. The kinetic energy in the lower troposphere in storm regions was enhanced by the incoming kinetic energy from the west boundary of the storm regions, by the downward transport of the kinetic energy  and by the conversion of the baroclinic potential energy into the kinetic one. The low level kinetic energy enhancement, energy accumulation and cold area establishment in the rainstorm area provided energy, dynamic conditions and unstable conditions for the occurrence of remote typhoon rainstorm.(5) There was  a precursory signal about occurrence of remote typhoon rainstorm, the positive energy advection generation in the lower troposphere in the rainstorm area was about 12 hours ahead of the rainstorm.

Key words: southwest low level jet, typhoon rainstorm, apparent heat energy, latent heat energy, dynamic energy conversion