Preprints
https://doi.org/10.5194/amt-2023-252
https://doi.org/10.5194/amt-2023-252
02 Jan 2024
 | 02 Jan 2024
Status: this preprint is currently under review for the journal AMT.

Lidar-radar synergistic method to retrieve ice, supercooled and mixed-phase clouds properties

Clémantyne Aubry, Julien Delanoë, Silke Groß, Florian Ewald, Frédéric Tridon, Olivier Jourdan, and Guillaume Mioche

Abstract. Mixed-phase clouds are not well represented in climate and weather forecasting models, due to a lack of the key processes
controlling their life cycle. Developing methods to study these clouds is therefore essential, despite the complexity of mixed-
phase cloud processes and the difficulty of observing two cloud phases simultaneously. We propose in this paper a new method
to retrieve the microphysical properties of mixed-phase clouds, ice clouds and supercooled water clouds using airborne or
satellite radar and lidar measurements. This method extends an existing variational method developed for ice clouds retrieval
using lidar, radar and passive radiometers. We assume that the attenuated lidar backscatter β at 532 nm is more sensitive to
particle concentration and is consequently mainly sensitive to the presence of supercooled water. In addition, radar reflectivity
Z at 95 GHz is sensitive to the size of hydrometeors and hence more sensitive to the presence of ice crystals. Consequently,
in the mixed-phase the supercooled liquid droplets are retrieved with the lidar signal and the ice crystals with the radar signal,
meaning that the retrieval rely strongly on a priori and errors values. This method retrieves then simultaneously the visible
extinction for ice αice and liquid αliq particles, the ice and liquid water contents IWC and LWC, the effective radius of ice
re,ice and liquid re,liq particles and the ice and liquid number concentrations Nice and Nliq. Moreover, total extinction αtot, total
water content TWC and total number concentration Ntot can also be estimated. As the retrieval of ice and liquid is different, it is
necessary to correctly identify each phase of the cloud. To this end, a cloud phase classification is used as input to the algorithm
and has been adapted for mixed-phase retrieval. The data used in this study are from DARDAR-MASK v2.23 products, based
on the CALIOP lidar and CPR radar observations, respectively from the CALIPSO and CloudSat satellites belonging to the
A-Train constellation launched in 2006. Airborne in situ measurements performed on the 7th April 2007 during the ASTAR
campaign and collected under the track of CloudSat-CALIPSO are compared to the retrievals of the new algorithm to validate
its performance. Visible extinctions and water contents properties derived from in situ measurements and the retrievals showed
similar trends and are globally in good agreement. The mean percent error between the retrievals and in situ is 39 % for αliq,
398 % for αice, 49 % for LWC and 75 % for IWC. It is also important to note that the temporal and spatial collocations are not
always optimal, that the sensibility of remote sensing and in situ are not the same and that in situ measurements uncertainties
are between 25 % and 60 %.

Clémantyne Aubry, Julien Delanoë, Silke Groß, Florian Ewald, Frédéric Tridon, Olivier Jourdan, and Guillaume Mioche

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-2023-252', Anonymous Referee #3, 23 Jan 2024
  • RC2: 'Comment on amt-2023-252', Anonymous Referee #2, 23 Jan 2024
  • RC3: 'Comment on amt-2023-252', Anonymous Referee #1, 24 Jan 2024
Clémantyne Aubry, Julien Delanoë, Silke Groß, Florian Ewald, Frédéric Tridon, Olivier Jourdan, and Guillaume Mioche
Clémantyne Aubry, Julien Delanoë, Silke Groß, Florian Ewald, Frédéric Tridon, Olivier Jourdan, and Guillaume Mioche

Viewed

Total article views: 428 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
307 96 25 428 12 14
  • HTML: 307
  • PDF: 96
  • XML: 25
  • Total: 428
  • BibTeX: 12
  • EndNote: 14
Views and downloads (calculated since 02 Jan 2024)
Cumulative views and downloads (calculated since 02 Jan 2024)

Viewed (geographical distribution)

Total article views: 423 (including HTML, PDF, and XML) Thereof 423 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 15 Apr 2024
Download
Short summary
The radar-lidar synergy is used to retrieve ice, supercooled water and mixed-phase clouds properties, making the most of the radar sensitivity to ice crystals and the lidar to the supercooled droplets. First analysis of the output of the algorithm run on the satellite data is compared with in situ data during an airborne Arctic field campaign, giving a mean percent error of 49 % for liquid water content and 75 % for ice water content.