## 3 Results and Discussion
### Verification of Classification Accuracy  
The accuracy of the previously proposed meteorological phenomenon classification algorithm was verified by considering nine cases based on intensive observation data: one case of AD, two cases of HZ, three cases of MI, and three cases of PR. The same observation periods as described in Sections 3.1 and 3.2 were considered, but the validation cases were excluded from this analysis. Table 5 shows the meteorological phenomena observed by the KMA as well as the results of the applied classification algorithms. All nine cases were consistent with the KMA observations. The results of back-trajectory analysis and mass concentration variability for AD and LH, which are long-distance transport cases, and one MI case are shown. Figure 8: Logarithmic probability density function for mass concentration versus particle diameter (D) for the following: (**a**) Asian dust (AD), (**b**) haze (HZ), (**c**) mist (MI), (**d**) precipitation (PR), and (**e**) clear days (CD) cases. Red lines show the optimum regression curve. \(d\) is the geometric mean diameter, and \(\sigma\) is the geometric standard deviation. The first case was an AD event occurring on 17 March 2009. The KMA site at Busan indicated that the AD event occurred in isolation, and the algorithm result was consistent with this finding. When assessing the backward trajectory model (Figure 9), we found that air masses generated near the Gobi Desert moved to the southern part of the Korean Peninsula. Based on the aerosol mass concentration time series in Busan and Anmyeondo, we further confirmed that an extreme AD event was observed in Anmyeondo on March 16, 2009, and it reached Busan at dawn on March 17, 2009. The time lag of the peak aerosol mass concentration at the two points was recorded as 6 h based on Mode 2. The median mass concentration of Mode 2 was 1.540 ug\(\cdot\)m\({}^{-3}\), and because the standard value (0.487 ug\(\cdot\)m\({}^{-3}\)) was exceeded, the phenomenon was determined as AD. The second case refers to an LH event occurring on 12 April 2009, which was classified as a simple HZ event by the KMA. For the 72-h backward trajectory analysis, air masses were introduced from Shandong Peninsula in China, and the high aerosol mass concentration of Mode 1 (which occurred in Anmyeondo on 11 April 2009) was observed in Busan on 11 April 2009 (Figure 10). The RH was approximately 63%, and the median mass concentration of Mode 2 was 0.237 ug\(\cdot\)m\({}^{-3}\). The concentration at Busan did not have a distinct peak compared to the AD case, but a high mass concentration of Mode 1 was observed at Anmyeondo. In addition, we determined that the air flowed to Busan during the back-trajectory analysis, and the mass concentration did not exceed the standard value (0.487 ug\(\cdot\)m\({}^{-3}\)); therefore, the phenomenon was identified as LH. \begin{table}
\begin{tabular}{c c c c c} \hline
**Case** & **Parameter** & **_Nt_ (\(\mu\)g\(\cdot\)m\({}^{-3}\))** & \(d\) (\(\mu\)m) & \(\sigma\) (\(\mu\)m) \\ \hline _Asian Dust_ & Mode 1 & 1.76 & 0.42 & 1.42 \\ _(AD)_ & Mode 2 & 4.03 & 5.10 & 1.52 \\  & Mode 1 & 3.00 & 0.38 & 1.36 \\ _Haze (HZ)_ & Mode 2 & 0.53 & 5.14 & 1.49 \\  & Mode 1 & 3.79 & 0.40 & 1.28 \\  & Mode 2 & 0.36 & 5.28 & 1.47 \\ _Precipitation_ & Mode 1 & 2.55 & 0.35 & 1.34 \\ _(PR)_ & Mode 2 & 0.36 & 5.49 & 1.51 \\ _Clear days (CD)_ & Mode 1 & 2.14 & 0.36 & 1.35 \\  & Mode 2 & 0.62 & 5.24 & 1.46 \\ \hline \end{tabular}
\end{table} 
Table 4: Lognormal fit parameters to the mass concentration distribution for each case, where _Nt_ is the total aerosol mass concentration, \(d\) is the geometric mean diameter, and \(\sigma\) is the geometric standard deviation.