EGU General Assembly 2020
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Study on the influence of different aerosol mixing states on lidar ratio

zhijie zhang
zhijie zhang
  • School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, 510275, P. R. China

             After years of development, Mie lidar has become an important technical means to explore aerosol particles in the atmosphere, and has been widely used to explore the optical and physical properties of aerosols in atmosphere. By Using backscatter signal collecting by lidar, optical characteristics of aerosols can be qualitatively analyzed. However, in order to get the actual value of optical parameters, the accurate lidar ratio (LR) (the ratio of extinction coefficient to back-scattering coefficient) is needed in inversion.

            Using the Mie scattering theory, the key parameter of inversion: LR, can be measured out. The value of LR has been discussed in detail by changing complex refractive index, size parameter  and field angle of a single particle. It is found that when the scale parameter is greater than 0.6, the value of LR increases first and then decreases with the increasing scale parameter, and there are several extremums; the value of LR decreases with the increasing imaginary part of the complex refractive index; the value of LR increases with the increasing filed angle.

            To study the influence of different mixing states on optical parameters of aerosol clusters, a three-component optical equilibrium spherical aerosol model is assumed. The results shows that when the mixing states of aerosol are complete external mixture, complete uniform internal mixture and complete coated mixture, the value of LR appears to be: complete uniform internal mixture > complete external mixture > complete coated mixture.

            Assuming that the hygroscopic growth factor of aerosol is a constant which does not increase with the particle size and its value is GF = 1.5[p2] , the value of LR after hygroscopic growing is discussed. It is found that the value of LR will increase after hygroscopic growing, but it still follows the law that: complete uniform internal mixture > complete external mixture > complete coated mixture.

            By correcting the value of LR, accurate extinction coefficient and back-scattering coefficient can be measured out with inversion. The production of lidar will be quantified instead of qualitative after doing this.

How to cite: zhang, Z.: Study on the influence of different aerosol mixing states on lidar ratio, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21217,, 2020


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displays version 1 – uploaded on 03 May 2020
  • CC1: Comment on EGU2020-21217, Franz Kanngiesser, 06 May 2020

    This appears to be a rather fascinating study.
    Unfortunately the statement of decreasing LR with increasing imaginary part of the refractive index, appears to be contradicted by the values listed in the table. I assume that's just a mistake.

    However, in a recent modelling study of soot aggregates embedded in a spherical coating, we saw in one case a lower LR for soot coated with a mildly absorbing coating, than for soot coated with a non-absorbing coating. Do you also consider differences in the refractive index of the core-shell geometries? And if so, did you observe a similar effect?
    The study, I referred to, is presented here: