dc.description.abstract | This study discusses the climatological characteristics of lightning and surface rainfall in Taiwan under three different types of weather systems between year 1989-2005. The three different types are typhoon, local thermal convective system and other convective systems. In order to discuss the temporal and spatial correlation between lightning and surface rainfall, three cases from each type of weather system were analyzed.
Lightnings mainly occur at the west part of Taiwan, on the west side of the Central Mountain Range. Lightning occurances are more often during May to September. The greatest part of lightnings happen during the local thermal convective systems and mainly gather up around the north-south oriented power transmission line at the west part of Taiwan. The ratio between –CG and +CG (the number of -CG divided by the number of +CG) during local thermal convective system is about 19, which is the largest among the three types of weather systems. The ratio between IC and total CG during year 2003-2005 is about 20.
The percentage of typhoon rainfall within annual total rainfall exhibits a rising trend between year 1989-2005, from ~20% to ~40%. During June to August, each month contributes about 30% of the annual total rainfall at the south-west part of Taiwan. The rainfall occur during these three months are mainly caused by typhoon and local thermal convective system. The correlation coefficient of typhoon rainfall and annual total rainfall is 0.79, while that of local thermal convective rainfall and other convective rainfall is 0.13 and 0.72 respectively.
In the local thermal convection system case, the area of the occurance of IC lightnings and rainfall are in good agreement, while CG lightnings happen around the maximum of the surface rainfall. In the other convective case, IC lightnings are very rare, and CG lightnings only happen in the area where local heavy rainfall occurs. | en_US |