## 3 Results and Discussion
### Aerosol Optical Properties  
#### 3.3.1 Aerosol Scattering Properties  
(1) Aerosol Scattering Coefficient  
The scattering coefficient of aerosols is an important value among the aerosol optical properties, because it reflects the scattering ability of the aerosols. The scattering coefficient variation at the wavelength of 550 nm (\(\sigma_{\mathrm{s}}\)_550) is shown in Figure 4a. It increased sharply during the haze period and reached its maximum value of 4.49 \(\mathrm{km}^{-1}\) during the afternoon of 11 June, which was the day with the worst conditions. During the haze, the mean value (2.32 \(\mathrm{km}^{-1}\)) was approximately 5.3 times that of normal weather (0.44 \(\mathrm{km}^{-1}\)). This result indicated that the haze episode was severe and that it could \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Date**} & **WS** & **WD** & **Temp** & **Pressure** & **RH** & **Visibility** \\  & **(m-s\({}^{-1}\))** & **(Degrees)** & **(\({}^{\circ}\)C)** & **(hPa)** & **(\%)** & **(km)** \\ \hline \multirow{2}{*}{6 June 2012} & 0.41 & 181.95 & 30.27 & 992.44 & 70.13 & 3.62 \\  & (0.21, 0.68) & (95.00, 256.13) & (29.84, 30.64) & (991.48, 992.99) & (68.62, 71.59) & (1.81, 6.75) \\ \multirow{2}{*}{7 June 2012} & 0.57 & 226.48 & 30.08 & 992.42 & 60.55 & 3.46 \\  & (0.22, 0.78) & (150.27, 258.59) & (29.79, 31.40) & (991.61, 993.24) & (59.36, 68.21) & (1.78, 4.30) \\ \multirow{2}{*}{8 June 2012} & 0.69 & 234.50 & 32.43 & 992.12 & 64.15 & 5.41 \\  & (0.42, 0.90) & (203.62, 250.28) & (30.89, 35.96) & (991.28, 992.84) & (52.87, 67.59) & (3.08, 9.72) \\ \multirow{2}{*}{9 June 2012} & 0.50 & 214.82 & 34.65 & 988.31 & 60.67 & 7.55 \\  & (0.34, 0.72) & (152.79, 239.41) & (32.79, 38.56) & (987.82, 991.85) & (49.60, 67.68) & (3.50, 12.93) \\ \multirow{2}{*}{10 June 2012} & 0.31 & 133.40 & 31.96 & 987.88 & 64.72 & 6.38 \\  & (0.24, 0.43) & (56.58, 190.36) & (29.86, 33.53) & (987.20, 989.00) & (60.72, 69.53) & (3.63, 8.55) \\ \multirow{2}{*}{11 June 2012} & 0.47 & 42.65 & 31.20 & 989.95 & 63.08 & 1.09 \\  & (0.21, 0.74) & (19.33, 186.79) & (29.17, 33.00) & (988.04, 990.79) & (59.79, 65.45) & (0.77, 6.91) \\ \multirow{2}{*}{12 June 2012} & 0.32 & 185.02 & 40.64 & 987.91 & 66.93 & 1.72 \\  & (0.11, 0.73) & (47.64, 240.46) & (36.42, 42.65) & (987.44, 989.73) & (51.15, 73.95) & (1.04, 5.47) \\ \multirow{2}{*}{13 June 2012} & 0.32 & 124.87 & 34.54 & 990.17 & 65.08 & 3.62 \\  & (0.18, 1.08) & (79.89, 198.18) & (31.13, 41.12) & (988.27, 990.98) & (45.20, 69.89) & (2.09, 7.45) \\ \multirow{2}{*}{14 June 2012} & 0.26 & 128.10 & 30.90 & 993.50 & 59.89 & 3.29 \\  & (0.21, 0.55) & (92.22, 242.92) & (29.78, 36.92) & (991.20, 994.38) & (47.53, 63.07) & (2.09, 4.34) \\ \hline \end{tabular} Median values are stated on the top line and the 10 th and 90 th percentiles are stated underneath within the parentheses.  
\end{table} 
Table 1: Meteorological information obtained during the study. have had adverse effects on human health. [PERSON] _et al._ found that the mean value of \(\sigma_{\text{s}}\_550\) on the eastern coast of China (ECH) under haze conditions was 1.050 \(\text{km}^{-1}\), and that the maximum value for ECH was 1.310 \(\text{km}^{-1}\)[23]. In a winter regional haze event in the NCP, the mean value of the scattering coefficient was determined as 0.58 \(\text{km}^{-1}\), which is 8.1 times higher than on non-haze days [3]. At Wuqing, [PERSON] _et al._ found a mean scattering coefficient of 0.74 \(\text{km}^{-1}\) during a pollution episode in spring and 0.87 \(\text{km}^{-1}\) in summer [49]. Both values are lower than that determined in Wuhan, indicating the severity of the Wuhan event. The rapid increase of the aerosol scattering coefficient was attributed mostly to the large local aerosol loading within the regional transport. The aerosol scattering Angstrom exponent (\(\alpha_{\text{s}}\)) reveals aerosol size information according to the Mie theory.