| dc.description.abstract | This study focus on the warm season (May-September) from 2016 to 2020 in recent years to conduct a statistical analysis of the characteristics of the afternoon thunderstorm environment in the central region of Taiwan. This study discuss the impact of different wind fields on the development of afternoon thunderstorms. The northeast wind (NE), east wind (EE), southeast wind (SE), south wind (SS), and southwest wind (SW) prevail in the warm season, respectively on afternoon thunderstorm days (TSA) and non-afternoon thunderstorm days (noTSA). Based on the differences between TSA and noTSA, we conducted environmental field analysis to discussed the environmental characteristics before the occurrence of afternoon thunderstorms and the environmental factors that can be used for forecasting. We hope this study could be benefit to future afternoon convective forecasting in central Taiwan. In this study we use the sounding data from the Magong Station with 00UTC and the ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) to conduct a comprehensive weather types analysis, as well as the data from the ground station of the Central Weather Bureau (CWB), to examine the temporal and spatial changes of the surface environmental field, and to explore the afternoon thunderstorms environmental characteristics in the central Taiwan.
The results of the study show that the location of the mid-subtropical high will affect the occurrence of afternoon convection. The more the high-pressure ridge extends to the west and the south, the environment in Taiwan tends to be more stable. When Taiwan is on the edge of subtropical high pressure, Taiwan′s environmental instability will be relatively high. Under different synoptic wind fields, the height of the obvious difference in temperature and humidity fields is not the same but affected by the wind direction and intensity of the wind field. The lower and middle environmental conditions of the TSA are warmer and humid, resulting in lower convective inhibition and less external force can reach the level of free convection. Coupled with larger convective available potential energy and precipitable water, makes TSA quite conducive to the development of convective environmental conditions. Near-surface sea breeze transports water vapor, which can be transported to inland areas. When the thermal effect is sufficient, it is easier to turn into clouds and precipitation, and the onshore wind will split into north or south due to the terrain effects on synoptic wind field, resulting in changes in the location of the precipitation hot zone. It shows that the precipitation hot zone is highly related to the influence of terrain effects on the prevailing surface wind field. | en_US |