[Obtaining aerosol backscattering coefficient using pure rotational Raman spectrum].
Atmospheric aerosol backscattering coefficient ratio can be obtained with the ratio of elastic signal to the total rotational Raman backscattering signal without assuming the ratio of aerosol extinction to backscatter. Generally, the intensity ofpartial rotational Raman spectrum lines instead of the total rotational Raman spectrum lines is measured. The intensity of the total rotational Raman spectrum lines is not dependent on the temperature, but the intensity of the partialrotational Raman spectrumlines is dependent on the temperature. So calculating aerosol backscattering coefficient ratio with the intensity of the partial rotational Raman spectrum lines would lead to an error. In the present paper, the change in the intensity sums of different rotational Raman spectrum lines with temperature was simulated and the errors of aerosol backscattering coefficient ratio derived from them were discussed. A new method was presented for measuring aerosol backscattering coefficient ratio, which needed not to measure the intensity of the total rotational Raman spectrum lines. Aerosol backscattering coefficient ratio could be obtained with the atmospheric temperature and a single rotational Raman spectrum line. Finally, a erosol backscattering coefficient ratio profiles of the atmosphere were acquired with the combined Raman lidar of our lab. The results show that there is no need to assume any relation between aerosol backscattering and extinction or to consider any wavelength calibration to determine the aerosol scattering coefficient.
Su
Jia
J
Key Lab of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, The Chinese Academy of Sciences, Hefei 230031, China. sujia0804@163.com
Zhang
Yin-chao
YC
Hu
Shun-xing
SX
Zhao
Pei-tao
PT
Cao
Kai-fa
KF
Wang
Shao-lin
SL
Xie
Jun
J