Differences in storm structure and internal dynamics of the two storm source regions over East Asia

Using a new localized multi-scale energetics analysis method and a feature tracking and compositing technique, this study investigates the structure and internal dynamics of the storms over the two storm source regions over East Asia based on data from the European Centre for Medium-Range Weather Forecasts ReAnalysis (ERA-40). It is found that the two regions are significantly different in both storm structure and internal dynamics. Storms in the south exhibit the bottom-trapped feature with perturbations intensified at the bottom, similar to the most unstable mode in the linear baroclinic model, whereas storms in the north have the largest amplitude in the upper troposphere, just as that described in terms of downstream development. Besides, it is found that storms in the south have stronger ageostrophic winds. Localized multi-scale energetics analysis result shows that they experience both baroclinic instability and barotropic instability. For storms in the north, however, barotropic instability is absent. We find that the buoyancy conversion and diabatic effect are much stronger in the south, which can be attributed to the stronger vertical motion and more vapor content there.