the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Retrievals of vertically resolved aerosol microphysical particle parameters with regularization from spaceborne Aerosol and Carbon dioxide Detection Lidar (ACDL)
Abstract. Using an improved regularization method, we attempt to derive microphysical parameters (effective radius ðððð, surface area concentration ððĄ, volume concentration ððĄ) of aerosol particle size distribution directly from the detection results of Aerosol and Carbon dioxide Detection Lidar (ACDL), which is the first spaceborne high spectral resolution lidar. The backscatter and extinction coefficients at 532 nm, 1064 nm, 1572 nm are adopted for regularization algorithm. Preliminary simulations for different aerosol types demonstrate the algorithm performance of the 3α+3β optical data combination. For monomodal aerosols, the retrieval errors are constrained within 15 % for ðððð, 30 % for ððĄ, and 35 % for ððĄ. In bimodal cases, errors increase to 18–35 % for ðððð, 35 % for ððĄ, and up to 60 % for ððĄ. Sensitivity analysis confirms that systematic errors of ±20 % in input optical data induce parameter uncertainties below 60 %. Case studies reveal four typical aerosols profiles: urban (ðððð~0.5 μm), smoke (ðððð~0.6 μm), dust (ðððð~0.65 μm), and marine (ðððð~0.85 μm). The inversion ðððð is compared with CALIPSO and LIVAS, which confirms high consistency for marine and dust, while urban and smoke retrievals show slightly larger. The inclusion of 1572 nm significantly enhances coarse-mode retrieval accuracy. The error statistics of the simulations and the actual comparison results show that the proposed inversion algorithm can reliably derive the particle size distribution parameters from the spaceborne multi-wavelength lidar ACDL. This work provides preliminary validation of ACDL's capability to retrieve vertically resolved global aerosol microphysical characterization.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2025-4208', Anonymous Referee #1, 16 Sep 2025
- AC1: 'Reply on RC1', ziyu Bi, 22 Sep 2025
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RC2: 'Comment on egusphere-2025-4208', Anonymous Referee #2, 16 Oct 2025
The manuscript represents the application of the regularization algorithm to the first spaceborne HSRL lidar ACDL, and enabling the retrievals of vertically resolved aerosol microphysical parameters. Although there is potential to improve the retrieval of the fine-mode particles, this work shows a valuable contribution by obtaining AMP from the spaceborne lidar and it is interesting. Before the manuscript can be publication, the following questions need to be addressed.
1. The authorâs choice of wavelengths in the inversion process differs from the commonly scheme (3Îą+2Îē). Please explain the basis for the selection of the input data combination in this paper.
2. In the actual atmosphere, the refractive index of the atmosphere varies significantly due to changes of humidity and the type of aerosols, and there is a lack of discussion on the sensitivity of the inversion results to the choice of refractive index.
3. Please provide a further explanation for the increase in the bimodal inversion errors in the simulation (volume concentration reaching 60%).
4. There is a lack of quantitative description of the ACDL data errors shown in Fig. 10, as well as the other two sets of comparison data.
5. It would be better to add the display of parameters for the ACDL system.Citation: https://doi.org/10.5194/egusphere-2025-4208-RC2 - AC2: 'Reply on RC2', ziyu Bi, 24 Oct 2025
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Authors analyze possibility to retrieve the particle size distribution from the measurements of space based HSRL lidar, using inversion with regularization. Lidar perform measurements at 3 wavelengths 532 nm, 1064 nm, 1572 nm and authors assume that 3 backscattering and 3 extinction coefficients are available.
This inversion technique is widely used for ground based lidars, but it is really a challenge to use it for satellite measurements. The main problem is to provide high quality of input data, because measurements from space are characterized by high noise. So, anybody, who tries to present such inversion, first of all should demonstrate profiles of aerosol backscattering and extinction coefficients with corresponding uncertainties. This is what I miss in this manuscript. Authors should explain how they calculate backscattering and extinction at 1064 and 1572 nm. I could also provide other comments, but question about input data quality is the main. I think, without it manuscript cannot be published.