| dc.description.abstract | This study uses the Lagrangian particle dispersion model – Windmodel to simulate each day during August 2003 to 2006. Through the distribution of the particles we discuss the relationship between the summer surface circulation and convection in Taiwan.
In order to understand the accumulation of the particles in dispersion process, we choose the particle calculating domain (120.35°E-120.90°E，23.6°N-24.0°N) , because there is the area of most highly frequency of lightning occurrences during August 2003 to 2006. We divide the particle calculating domain into the rectangle areas which have the same width of longitude. We can know the particles variation in the calculating domain in a day through the calculation of the particles variation in different areas.
First, this study chooses the cases which have more lightning occurrences because of the convection systems development in the afternoon and have the least lightning occurrences of August 2006. Then we calculate the particles variation of the case that has more (lower) lightning occurrences in twenty-four hours. Next, we calculate the correlation coefficient Ra(Rb) of the particles variation of the case that has more (lower) lightning occurrences and the particles variation of the other days in whole calculating domain. The result reveals that some cases with high Ra value have the development of the convection system and several thousand lightning occurrences in the afternoon in Taiwan. However, these cases with high Ra value also have high Rb value.
In the following discussion, we use the several particles variation of the different particle calculating domains. To define the correlation coefficient R1(R2) is the correlation of the particles variation of the case that has more (lower) lightning occurrences and the particles variation of the other days in A01 domain(120.35°E-120.40°E，23.6°N-24.0°N). Then we calculate the correlation of R1(R2) and daily lightning occurrences during August 2003 to 2006. The best correlation is 0.5 between R1 and the daily lightning occurrences in the area of 120°E-121°E, 23°N-24°N. It reveals that the accuracy is about 50% if we use R1 to judge the frequency of daily lightning occurrences in a day.
In case study, we discuss a case that the particles increase in the afternoon, and it has more occurrences of lightning near the particle calculating domain at the same time. We see the impact of the sea-breeze circulation on particles through the two-dimensional particles distribution figures. It shows the most occurrences of lightning near the particle calculating domain in a day, almost the same time the particles have a peak in the divided particle calculating domain which the location is in the land and far away the ocean. | en_US |