Buchumschlag

Optical Properties of Near-Surface Cloud Layers and Their Interactions with Aerosol Layers: A Case Study of Australia Based on CALIPSO

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Veröffentlicht in:Atmosphere vol. 16, no. 7 (2025), p. 793-811
1. Verfasser: Zhang, Miao
Weitere Verfasser: Zhang Yating, Wang, Yingfei, Liang Jiwen, Zilu, Yue, Song Wenkai, Han, Ge
Veröffentlicht:
MDPI AG
Schlagworte:
Australia
Southern Hemisphere
Cytotoxicity
Optical thickness
Correlation analysis
Datasets
Aerosols
Troposphere
Mountains
Lymphocytes T
Clouds
Cloud development
Lidar
Aerosol layers
Night-time
Seasonal variations
Atmospheric stability
Radiation
Climate change
Heterogeneity
Statistical analysis
Regional analysis
Cloud properties
Cloud height
Precipitation
Diurnal variations
Remote sensing
Optical properties
Regional planning
Satellite observation
Low clouds
Aerosol effects
Cloud systems
Seasonal variation
Stratiform clouds
Data processing
Satellites
Patchiness
CALIPSO (Pathfinder satellite)
Aerosol optical properties
Optical analysis
Spatial heterogeneity
Lower troposphere
Nighttime
Regional differences
Night
Orographic effects
Aerosol-cloud interactions
Cloud formation
Radiative cooling
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Abstract:This study utilized Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite level-2 data with high-confidence cloud–aerosol discrimination (|CAD| > 70) to investigate the optical properties, vertical distributions, seasonal variations, and aerosol interactions of near-surface cloud layers (cloud base height < 2.5 km) over Australia from 2006 to 2021. This definition encompasses both traditional low clouds and part of mid-level clouds that extend into the lower troposphere, enabling a comprehensive view of cloud systems that interact most directly with boundary-layer aerosols. The results showed that the optical depth of low clouds (CODL) exhibited significant spatial heterogeneity, with higher values in central and eastern regions (often exceeding 6.0) and lower values in western plateau regions (typically 4.0–5.0). CODL values demonstrated clear seasonal patterns with spring peaks across all regions, contrasting with traditional summer-maximum expectations. Pronounced diurnal variations were observed, with nighttime CODL showing systematic enhancement effects (up to 19.29 maximum values compared to daytime 11.43), primarily attributed to surface radiative cooling processes. Cloud base heights (CBL) exhibited counterintuitive nighttime increases (41% on average), reflecting fundamental differences in cloud formation mechanisms between day and night. The geometric thickness of low clouds (CTL) showed significant diurnal contrasts, decreasing by nearly 50% at night due to enhanced atmospheric stability. Cloud layer number (CN) displayed systematic nighttime reductions (18% decrease), indicating dominance of single stratiform cloud systems during nighttime. Regional analysis revealed that the central plains consistently exhibited higher CODL values, while eastern mountains showed elevated cloud heights due to orographic effects. Correlation analysis between cloud and aerosol layer properties revealed moderate but statistically significant relationships (|R| = 0.4–0.6), with the strongest correlations appearing between cloud layer heights and aerosol layer heights. However, these correlations represent only partial influences among multiple factors controlling cloud development, suggesting measurable but modest aerosol effects on cloud properties. This study provides comprehensive observational evidence for cloud optical property variations and aerosol–cloud interactions over Australia, contributing to an improved understanding of Southern Hemisphere cloud systems and their climatic implications.
ISSN:2073-4433
DOI:10.3390/atmos16070793
Quelle:Publicly Available Content Database