Sea ice melt and freeze onset from space-based lidar measurements

This paper describes a method to accurately identify the melt and freeze onset of sea ice using polar-orbiting Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar measurements from the Cloud and Aerosol Lidar and Infrared Pathfinder Observation (CALIPSO) mission. The proposed method is based on the integrated depolarization ratio and attenuated backscatter to separate surface melting and freezing from open water and snow/ice covered surfaces. The method has been applied to CALIOP data over different Arctic regions to study the annual variability of melt and freeze onset. The > 10 years of CALIOP continuous observations of the sea ice melt and freeze onset will benefit the scientific research communities to better assess and quantify global environmental changes.