Title :
Spectral behavior of imaginary part of aerosol refractive index obtained from ground-based sun-sky radiometer measurements in Beijing, China
Author :
Wang, Ling ; Li, Zhengqiang ; Tian, Qingjiu
Author_Institution :
Int. Inst. for Earth Syst. Sci., Nanjing Univ., Nanjing, China
Abstract :
Black carbon, organic matter, and mineral dust are the main absorption components in atmospheric aerosols and their fractions determine the wavelength dependence of absorption. We analyze the spectral measurements of imaginary refractive indices (k) from 440 to 1020 nm obtained from ground-based AErosol RObotic NETwork sun-sky radiometer located in Beijing. The results show that the k spectra in Beijing have a wavelength dependent characteristic, with k at 440 nm significantly higher than that at the other three bands. Hence, the ratio of k(440 nm) to k(670 nm) is established to express the k spectral behavior. A significant seasonal variations of k(440 nm)/k(670 nm) is found in Beijing, with maximum value of about 3.5 appeared in March, and minimum value of about 0.9 in August. This is consistent with the variation trends of absorption angstrom exponent, indicating that k(440 nm)/k(670 nm) is also a useful tool in identifying aerosol composition.
Keywords :
aerosols; atmospheric composition; dust; Beijing; China; absorption wavelength; aerosol composition; aerosol refractive index; angstrom exponent; atmospheric aerosols; black carbon; ground-based AErosol RObotic NETwork sun-sky radiometer; ground-based sun-sky radiometer measurements; imaginary refractive indices; mineral dust; organic matter; spectral behavior; spectral measurements; wavelength 440 nm to 1020 nm; Absorption; Aerosols; Atmospheric measurements; Minerals; Radiometry; Refractive index; Springs; aerosol; chemical components; refractive index; sun-sky radiometer;
Conference_Titel :
Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International
Conference_Location :
Munich
Print_ISBN :
978-1-4673-1160-1
Electronic_ISBN :
2153-6996
DOI :
10.1109/IGARSS.2012.6350337