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

摘要：

从能量角度分析台风和暴雨区显热能、潜热能和动能的时空分布特征，定量讨论台风强度长时间维持和暴雨区远距离降水突然增幅过程中能量加强的成因以及动能的补充途径。结果表明：（1）台风中心和暴雨区上空潜热能比显热能小一个量级，但潜热能平流明显大于显热能平流，潜热能对台风中心和暴雨区总能量增量的贡献大于显热能。（2）台风远距离暴雨发生时，暴雨区低层是一个深厚的潜热能大值区，凝结潜热释放有利于暴雨发生，低层是显热能和气温低值区，冷区的存在增加了暴雨区上空斜压不稳定，对暴雨具有增幅作用。（3）区域外能量的补充是“海棠”登陆后强度长时间维持的主要原因，西南风急流是显热能和潜热能补充台风的主要途径，潜热能增量远大于显热能增量。（4)“海棠”登陆后强度长时间维持导致西南急流加强，暴雨区低层显热能平流和潜热能平流也得到加强。暴雨区西边界纬向动能平流的加强、中高层动能的下传和斜压不稳定能量的转化使低层动能得到加强。低层动能加强、能量的积累和冷区的建立为台风远距离暴雨的发生提供能量、动力条件和不稳定条件。（5）台风远距离暴雨的发生具有前兆性，暴雨区低层出现正能量平流时间提前强降水发生时间约12 h。

关键词: 西南低空急流, 台风暴雨, 显热能, 潜热能, 动能转换