Lidar measurements of thin laminations within Arctic clouds

Abstract

Very thin ( < 10 m) laminations within Arctic clouds have been observed in all seasons using the Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh–Mie–Raman lidar (CRL) at the Polar Environment Atmospheric Research Laboratory (PEARL; located at Eureka, Nunavut, in the Canadian High Arctic). CRL's time (1 min) and altitude (7.5 m) resolutions from 500 m to greater than 12 km altitude make these measurements possible. We have observed a variety of thicknesses for individual laminations, with some at least as thin as the detection limit of the lidar (7.5 m). The clouds which contain the laminated features are typically found below 4 km, can last longer than 24 h, and occur most frequently during periods of snow and rain, often during very stable temperature inversion conditions. Results are presented for range-scaled photocounts at 532 and 355 nm, ratios of 532∕355 nm photocounts, and the 532 nm linear depolarization parameter, and with context provided by twice-daily Eureka radiosonde temperature and relative humidity profiles.