Efficient single-scattering look-up table for lidar and polarimeter water cloud studies

Optics Letters, vol. 48, pp. 13

Abstract

Combined lidar and polarimeter retrievals of aerosol, cloud, and ocean microphysical properties involve single-scattering cloud calculations that are time consuming. We create a look-up table to speed up these calculations for water droplets in the atmosphere. In our new Lorenz–Mie look-up table we tabulate the light scattering by an ensemble of homogeneous isotropic spheres at wavelengths starting from 0.35 µm. The look-up table covers liquid water cloud particles with radii in the range of 0.001–500 µm while gaining an increase of up to 104 in computational speed. The covered complex refractive indices range from 1.25 to 1.36 for the real part and from 0 to 0.001 for the imaginary part. We show that we can precisely compute inherent optical properties for the particle size distributions ranging up to 100 µm for the effective radius and up to 0.6 for the effective variance. We test wavelengths from 0.35 to 2.3 µm and find that the elements of the normalized scattering matrix as well as the asymmetry parameter, the absorption, backscatter, extinction, and scattering coefficients are precise to within 1% for 96.7%–100% of cases depending on the inherent optical property. We also provide an example of using the look-up table with in situ measurements to determine agreement with remote sensing. The table together with C++, Fortran, MATLAB, and Python codes to interpolate the complex refractive index and apply different particle size distributions are freely available online.

Authors 18

1. Eduard Chemyakin

   Langley Research Center · Science Systems and Applications (United States)

   Affiliation as printed

   NASA Langley Research Center (LaRC)

   Science Systems and Applications, Inc. (SSAI)

2. Snorre Stamnes

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

3. Johnathan W. Hair

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

4. S. P. Burton

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

5. Adam Bell

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

6. C. A. Hostetler

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

7. R. A. Ferrare

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

8. Jacek Chowdhary

   Goddard Institute for Space Studies · Columbia University

   Affiliation as printed

   Columbia University

   NASA Goddard Institute for Space Studies (GISS)

9. Richard H. Moore

   Langley Research Center

   Affiliation as printed

   NASA Langley Research Center (LaRC)

10. Luke D. Ziemba

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

11. Ewan Crosbie

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

12. Claire E Robinson

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

13. Michael A. Shook

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

14. Lee K. Thornhill

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

15. Edward L. Winstead

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

16. Yongxiang Hu

    Langley Research Center

    Affiliation as printed

    NASA Langley Research Center (LaRC)

17. Bastiaan van Diedenhoven Aachen SRON Netherlands Institute for Space Research

    Space Research Organisation Netherlands

    Affiliation as printed

    SRON Netherlands Institute for Space Research

18. Brian Cairns

    Goddard Institute for Space Studies

    Affiliation as printed

    NASA Goddard Institute for Space Studies (GISS)