Preprints
https://doi.org/10.5194/amt-2022-10
https://doi.org/10.5194/amt-2022-10
 
14 Feb 2022
14 Feb 2022
Status: a revised version of this preprint was accepted for the journal AMT.

Detection of supercooled liquid water clouds with ceilometers: Development and evaluation of deterministic and data-driven retrievals

Adrien Guyot1, Alain Protat1, Simon P. Alexander2, Andrew R. Klekociuk2, Peter Kuma3, and Adrian McDonald4 Adrien Guyot et al.
  • 1Australian Bureau of Meteorology, Melbourne, Victoria, Australia
  • 2Australian Antarctic Division, Kingston, Tasmania, Australia
  • 3Department of Meteorology, Stockholm University, Stockholm, Sweden
  • 4University of Canterbury, Christchurch, New Zealand

Abstract. Cloud and aerosol lidars measuring backscatter and depolarization ratio are most suitable instruments to detect cloud phase (liquid, ice, or mixed phase). However, such instruments are not widely deployed as part of operational networks. In this study, we propose a new algorithm to detect supercooled liquid water clouds based solely on ceilometers measuring only co-polarisation backscatter. We utilise observations collected at Davis, Antarctica, where low-level, mixed phase clouds, including supercooled liquid water (SLW) droplets and ice crystals remain poorly understood, due to the paucity of ground-based observations. A 3-month set of observations were collected during the austral summer of November 2018–February 2019, with a variety of instruments including a depolarization lidar and a W-Band cloud radar which were used to build a 2-dimensional cloud phase mask distinguishing SLW and mixed phase clouds. This cloud phase mask is used as the reference to develop a new algorithm based on the observations of a single polarisation ceilometer operating in the vicinity for the same period. Deterministic and data-driven retrieval approaches were evaluated: an extreme gradient boosting (XGBoost) framework ingesting backscatter average characteristics was the most effective method at reproducing the classification obtained with the combined radar-lidar approach with an accuracy as high as 0.91. This study provides a new SLW retrieval approach based solely on ceilometer data and highlights the considerable benefits of these instruments to provide intelligence on cloud phase in polar regions that usually suffer from a paucity of observations.

Adrien Guyot 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-2022-10', Anonymous Referee #1, 14 Mar 2022
    • AC1: 'Reply on RC1', Adrien Guyot, 03 May 2022
  • RC2: 'Comment on amt-2022-10', Anonymous Referee #2, 31 Mar 2022
    • AC2: 'Reply on RC2', Adrien Guyot, 03 May 2022

Adrien Guyot et al.

Data sets

PLATO data Adrien Guyot, Simon Alexander, Alain Protat, Andrew Klekociuk, & Adrian McDonald https://doi.org/10.5281/zenodo.5832199

Adrien Guyot et al.

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Short summary
Ceilometers are instruments that are widely deploy as part of operational networks. They are usually not able to detect cloud phase. Here, we propose an evaluation of various methods to detect supercooled liquid water with ceilometer observations, using an extensive dataset from Davis, Antarctica. Our results highlight the possibility for ceilometers to detect supercooled liquid water in clouds.