Abstract
In order to make clear the process of energy production in a tropical cyclone, Typhoon “Harriet” is studied during its stage of decay and transformation into an extratropical cyclone.
Analysing the temperature field, it is shown that the thermal structure changes from the symmetric to the asymmetric configuration and that the horizontal extent of the warm core decreases. From the analysis of the surface wind field, the velocity convergence is computed, and some characteristic features of its distribution are described. The intensification of the surface front near the typhoon in later stages is discussed from the standpoint of kinematics.
From the expectation that the modification of the structure might cause some changes in production rate of kinetic energy, the correlation between the temperature at 700mb level and the surface convergence, and also the amount of the work done by difference of the geopotential between the inner and the outer region are estimated. The result shows that the correlation changed such that it makes the production rate of kinetic energy increased, whereas the amount of the work is remarkably decreased.
