Raman lidar-derived optical and microphysical properties of ice crystals within thin Arctic clouds during PARCS campaign

• Published in: Atmospheric Measurement Techniques
• Main Authors: Chazette, Patrick, Raut, Jean-Christophe
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: Arctic stratiform clouds; lidar; optical properties; ice microphysical properties; effective radius; ice water content 30; [SDU]Sciences of the Universe [physics]; Arctic; Norway
• Online Access: https://insu.hal.science/insu-04172412; https://insu.hal.science/insu-04172412v2/document; https://insu.hal.science/insu-04172412v2/file/amt-16-5847-2023.pdf; https://doi.org/10.5194/amt-16-5847-2023

International audience Cloud observations in the Arctic are still rare, which requires innovative observation techniques to assess ice crystal properties. We present an original approach us- ing the Raman lidar measurements applied to a case study in northern Scandinavia. The vertical profiles of the optical properties, the effective radius of ice crystals and ice water content (IWC) in Arctic semi-transparent clouds were as- sessed using quantitative ground-based lidar measurements at 355 nm performed from 13 to 26 May 2016 in Hammer- fest (north of Norway, 70◦39′48′′ N, 23◦41′00′′ E). The field campaign was part of the Pollution in the ARCtic System (PARCS) project of the French Arctic Initiative. The pres- ence of low-level semi-transparent clouds was noted on 16 and 17 May. The cloud base was located just above the at- mospheric 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 se- lected case studies with cloud optical thickness (COT) lower than 2 and out of supercooled liquid pockets. 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. Us- ing Mie computations, we determine effective radii between ∼ 7 and 25 μm in the clouds for ice water contents between 1 and 8 mg m−3, respectively. The uncertainties regarding the effective radii and ice water content are on average 2 μm and 0.65 mg m−3, respectively.