mesoscale features and the lightning distribution in tyohoon morakot after it passed Taiwan

An observational analysis on mesoscale features and the lightning distribution over Taiwan after the passage of typhoon “Morakot” is conducted. The main objective of the study is to investigate the evolution of deep convection and the related significant lightning activity. The height of cloud convection that produce significant lightning is identified and the associated horizontal convergence is calculated by using Doppler radars of Cigu and Makung.

Although the center of Morakot made landfall in Hualien County along the central east coast of Taiwan and passed over the central northern part of the island, Southern Taiwan experienced the heaviest rainfall particularly in the mountainous area. Based on the 24-hr accumulated rainfall recorded by Central Weather Bureau, the heaviest rainfall was recorded after the typhoon Morakot made landfall traversing the mountainous area of central Taiwan. One of the striking features during the passage of Morakot are the unprecedented rainfall over Southern Taiwan particularly the mountainous area and significant intra-cloud lightning activity in the Taiwan Strait along with the line of convective rain cells were detected by the lightning detection system. In this study, the evolution of the lightning activity associated with the developing convection observed by the Doppler radar is studied. It is interesting to point out that the heaviest lightning was observed over the Taiwan Strait instead of inland. Over the mountain, where the heaviest rainfall occurred the lightning activity was a minimum. Interpretation of this feature will be discussed in the presentation.