2016年臺灣梅雨季午後對流降雨分析

During the Meiyu season (May and June) of year 2016, the seasonal mean temperature reaches the record high in Taiwan. Because the change in local temperature refers the change in local atmospheric thermal instability, which is important to the convective afternoon rainfall (hereafter CAR) formation, it is expected that the rainfall characteristics in Taiwan during the 2016 Meiyu season are very different to the climatological mean status. The main objective of this study is to find out how the 2016 Meiyu season rainfall characteristics (especially CAR) in Taiwan have changed in response to the atmospheric thermodynamical changes. Using the data extracted from 21 surface observations in Taiwan, our results showed that for most stations during the 2016 Meiyu season (1) the occurrence frequency of CAR is above normal, in response to the increase in local thermal instability; (2) the magnitude of CAR rate is below normal, in response to the decrease in moisture flux convergence; (3) the CAR’s contribution to total rainfall amount is above normal due to the increase in CAR frequency not the change in CAR rate. Analyses also indicated that the frontal rainfall amount during the 2016 Meiyu season is below normal, mainly due to that the intensification of subtropical high has prevent the Meiyu frontal systems moving southward to affect Taiwan.