Preprints
https://doi.org/10.5194/amt-2023-122
https://doi.org/10.5194/amt-2023-122
07 Jul 2023
 | 07 Jul 2023
Status: a revised version of this preprint is currently under review for the journal AMT.

Optical and microphysical properties of ice crystals in Arctic clouds from lidar observations

Patrick Chazette and Jean-Christophe Raut

Abstract. The vertical profiles of the optical properties, effective radius of ice crystals and ice water content (IWC) in Arctic semi-transparent stratiform clouds were assessed using quantitative ground-based lidar measurements performed from 13 to 26 May 2016 in Hammerfest (north of Norway, 70° 39′ 48″ North, 23° 41′ 00″ East). The field campaign was part of the Pollution in the ARCtic System (PARCS) project of the French Arctic Initiative. The presence of low-level semi-transparent stratus clouds was noted on 16 and 17 May, and they were sampled continuously by a ground-based Raman-N2 lidar emitting at the wavelength of 355 nm. These clouds were located just above the atmospheric boundary layer where the 0 °C isotherm reached around 800 m above the mean sea level (a.m.s.l.). To ensure the best penetration of the laser beam into the cloud, we selected case studies with cloud optical thickness (COT). Lidar-derived multiple scattering coefficients were found to be close to 1 and ice crystal depolarization around 10 %, suggesting that ice crystals were small and had a rather spherical shape. This agrees with our Mie computations determining effective radii between ~5 and 20 µm in the clouds for ice water contents between 1 and 8 mg m-3, respectively. Direct estimate of the microphysical parameters of ice clouds via lidar measurements is a significant asset for the study of their large-scale radiative impact, while reducing the need for experimental resources.

Patrick Chazette and Jean-Christophe Raut

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-2023-122', Anonymous Referee #1, 19 Jul 2023
  • RC2: 'Comment on amt-2023-122', Anonymous Referee #2, 23 Jul 2023

Patrick Chazette and Jean-Christophe Raut

Patrick Chazette and Jean-Christophe Raut

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Short summary
The vertical profiles of effective radius of ice crystals and ice water content in Arctic semi-transparent stratiform clouds were assessed using quantitative ground-based lidar measurements. The field campaign was part of the Pollution in the ARCtic System (PARCS) project which took place from 13 to 26 May 2016 in Hammerfest (70° 39′ 48″ N, 23° 41′ 00″ E). We show that under certain cloud conditions, lidar measurement combined with a dedicated algorithmic approach is an efficient tool.