Objective identification of aerosol transport regimes from long-term polarization micro-pulse lidar observations over coastal Antarctica

Le résumé fourni par la source

Long-term polarization-sensitive micro-pulse lidar (PMPL) observations provide valuable information on aerosol transport over coastal Antarctica. Still, the interpretation of aerosolenhanced layers has largely relied on manual inspection of quick-look images. Here we propose an objective image-based framework for identifying aerosol transport regimes from PMPL observations at Syowa Station, East Antarctica, during 2016–2022. Aerosol-enhanced layers were first detected using the backscatter ratio, its temporal variability, and the particle depolarization ratio. Image features were then extracted from PMPL quick-look images using a pre-trained ResNet50 convolutional neural network, standardized, reduced in dimensionality by principal component analysis, and classified by k-means clustering. A total of 254 aerosol events were identified and classified into two transport regimes with distinct vertical structures: one characterized by vertically extensive aerosol layers and the other by shallow, near-surface layers. Independent composite analyses of ERA5 500-hPa geopotential height anomalies indicate that the two regimes occur under different synoptic environments. These results suggest that PMPL observations alone contain sufficient information to objectively identify physically meaningful aerosol transport regimes without using meteorological information in the classification. The framework provides a reproducible tool for long-term analyses of Antarctic aerosol transport.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.