Preprints
https://doi.org/10.5194/amt-2020-504
https://doi.org/10.5194/amt-2020-504

  07 Jan 2021

07 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal AMT.

Estimating optical extinction of liquid water clouds in the cloud base region

Karolina Sarna1, David P. Donovan2, and Herman W. J. Russchenberg1 Karolina Sarna et al.
  • 1TU Delft Climate Institute, Faculty of Civil Engineering and Geotechnology, Delft University of Technology, Stevinweg 1, 2628 CN, Delft, The Netherlands
  • 2Royal Netherlands Meteorological Institute (KNMI), P.O. Box 201, 3730AE, De Bilt, The Netherlands

Abstract. Accurate lidar-based measurements of cloud optical extinction, even though perhaps limited to the cloud base region, are useful. Arguably, more advanced lidar techniques (e.g. Raman) should be applied for this purpose. However, simpler polarization and backscatter lidars offer a number of practical advantages (e.g. better resolution, more continuous and numerous time series). In this paper we present a backscatter lidar signal inversion method for the retrieval of the cloud optical extinction in the cloud base region. Though a numerically stable method for inverting lidar signals using a far-end boundary value solution has been earlier demonstrated and may be considered well-established (i.e. the Klett inversion), the application to high-extinction clouds remains problematic. This is due to the inhomogeneous nature of real clouds, the finite range-resolution of many practical lidar systems and multiple-scattering effects. We use an inversion scheme where a backscatter lidar signal is inverted based on the estimated value of cloud extinction at the far end of the cloud and apply a correction for multiple-scattering within the cloud and a range resolution correction. By applying our technique to the inversion of synthetic lidar data, we show that for a retrieval of up to 90 m from the cloud base it is possible to obtain the cloud optical extinction within the cloud with an error better than 5 %. In relative terms, the accuracy of the method is smaller at the cloud base but improves with the range within the cloud until 45 m and deteriorates slightly until reaching 90 m from the cloud base.

Karolina Sarna et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2020-504', Anonymous Referee #1, 17 Feb 2021
    • AC1: 'Reply on RC1', Karolina Sarna, 09 Apr 2021
  • RC2: 'Comment on amt-2020-504', Anonymous Referee #2, 21 Feb 2021
    • AC2: 'Reply on RC2', Karolina Sarna, 09 Apr 2021

Karolina Sarna et al.

Karolina Sarna et al.

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