Detection of cloud phase using ceilometer observations in New Zealand and the Southern Ocean. ...

• Main Author: Whitehead, Luke
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Canterbury 2023
• Subjects: Southern Ocean
• Online Access: https://dx.doi.org/10.26021/15045; https://ir.canterbury.ac.nz/handle/10092/106162

Supercooled liquid water (SLW) clouds are commonly observed in the Southern Hemisphere but are poorly represented in current climate models. Due to signal attenuation, satellite borne lidar observations of SLW are biased, so surface-based measurements are needed for understanding the distribution of SLW cloud for the purposes of model evaluation. The use of depolarization lidar to measure atmospheric volume depolarization ratio (VDR) is a common technique in classifying cloud phase (liquid or ice). Unfortunately, such lidars are uncommon and not suited to remote and extended measurement campaigns. This thesis is focused on identifying whether ceilometers (simple, low-power lidars) can be utilized to quantify SLW occurrence over the Southern Hemisphere, particularly the Southern Ocean. Previous work has established a technique to detect supercooled liquid water containing clouds (SLCC) from ceilometer retrievals, using a supervised machine learning model. Utilizing a depolarization lidar training dataset from ...