| The daily average monitoring data of PM10、PM2.5 and PM1 at Mt. Chengdu and meteorological elements data at Mt. Wenjiang during 2009 to 2011 were used to analyze the temporal distribution characteristics of PM10, PM2.5 and PM1 and the correlations among them. Additionally, the relationships between the particle matters and the meteorological elements were also studied. The research indicated that the variations of the average mass concentrations of PM10, PM2.5 and PM1 were generally the same in Chengdu, showing "V" distributions(except April), which showed that the peak(troughs) values of average mass concentrations of PM10, PM2.5 and PM1 appeared in January (in September), respectively. From 2009 to 2011, the inter-annual average mass concentrations of PM10, PM2.5 and PM1 had the same changing trend that values reduced year by year. The correlations analysis among PM10, PM2.5 and PM1 showed that the correlation coefficients of daily concentrations of PM10 with PM2.5, PM10 with PM1 and PM2.5 with PM1 were generally high, reached to 0.91,0.83 and 0.98, respectively. In addition, the average ratios of PM2.5/PM10, PM1/PM10 and PM1/PM2.5 were 84.61%,7.82% and 91.71%, respectively. It could be inferred that the fine particles were the main particles over Chengdu Region. The influence of meteorological elements to the particle matters were differently from each other. Except the air pressure, negative correlations existed between the particle matters and wind speed, temperature, precipitation, relative humidity and visiblity.The characteristics of aerosol optical depth (AOD) and Angstrom exponent retrieved from the CE-318 sunphotometer at the Chengdu station from February 2007 to December 2009 were studied. It could be concluded that high monthly AOD were observed in March, August and December. The maximum AOD values at 1020 nm,870 nm,670 nm and 440 nm in March were 0.55±0.13,0.64±0.16,0.85±0.22,1.29±0.38, respectively. The AOD values in August at these four wavelengths were 0.42±0.15, 0.53±0.20,0.76±0.29 and 1.19±0.38, respectively. The AOD values in December were 0.44±0.11,0.54±0.14,0.75±0.22 and 1.16±0.36, respectively, on the other hand, low values were observed in October, the minimum value of AOD appeared in October. The values at the 4 wavelengths above were 0.19±0.06,0.24±0.08,0.32±0.12 and 0.50±0.19, respectively. The minimum value of the Angstrom exponent occurred in April (0.94 ± 0.31), and the maximum value was 1.24 ± 0.16 in November. In addition, monthly variations in Angstrom exponent were opposite to the AOD in March. The Multi-peak Gauss Fitting Method were used for studying the AOD frequency, the results showed that there was a bi-modal distribution of the AOD centred at about 0.59 and 1.06. Besides, the Angstrom exponent single peak distributions centred at approximately 1.12.Aerosol optical depth (AOD) and Angstrom exponent under three typical weather cases were compaered and dicussed. From the results, it could be found that the AOD on the dust day was the largest while minimum AOD occurred on the haze day. On the contrast, the Angstrom exponent distributions among three weather conditions were opposite to the AOD. By the 72-hour back-trajectory analysis, it was inferred that the origin of the air masses largely affected the aerosol optical properties over the Chengdu Region.Combined with the data of SO2, NO2 and PM10 from Environmental monitoring station at Chengdu, the relationships between AOD and these three atmospheric compositons were learned. The correlation coefficients between AOD and SO2, NO2 and PM10 were only 0.44,0.35 and 0.43, respecticely, which meaned that there was a complicated (not linear) positive relationship between AOD and the atmospheric composition because of the complex influence mechanism. |
PDF Full Text Request