Characteristics of surface energy balance and atmospheric circulation during hot-and-polluted episodes and their synergistic relationships with urban heat islands over the Pearl River Delta region

This study analyzed the nature, mechanisms and drivers for hot-and-polluted episodes (HPEs) in the Pearl River Delta, China. Numerical model simulations were conducted for the summer and autumn of 2009–2011. A total of eight HPEs were identified, mainly occurring in August and September. K-means clu...

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Bibliographic Details
Published in:Atmospheric chemistry and physics 2021-09, Vol.21 (17), p.13443-13454
Main Authors: Nduka, Ifeanyichukwu C, Tam, Chi-Yung, Guo, Jianping, Yim, Steve Hung Lam
Format: Article
Language:English
Subjects:
Air pollution
Analysis
Atmospheric boundary layer
Atmospheric circulation
Climate change
Cluster analysis
Clustering
Convection
Cyclones
Energy
Energy balance
Environmental protection
Heat
Heat islands
High temperature
Hurricanes
Hybrid systems
Identification
Investigations
Low wind speeds
Lower atmosphere
Mathematical models
Numerical models
Numerical simulations
Observatories
Pollution
Radiative forcing
Rivers
Surface energy
Surface energy balance
Surface properties
Synergistic effect
Tropical climate
Tropical cyclones
Urban areas
Urban heat islands
Vector quantization
Weather
Wind speed
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Summary:This study analyzed the nature, mechanisms and drivers for hot-and-polluted episodes (HPEs) in the Pearl River Delta, China. Numerical model simulations were conducted for the summer and autumn of 2009–2011. A total of eight HPEs were identified, mainly occurring in August and September. K-means clustering was applied to group the HPEs into three clusters based on their characteristics and mechanisms. We found three HPEs were driven by weak subsidence and convection induced by approaching tropical cyclones (TC-HPE) and two HPEs were controlled by calm (stagnant) conditions (ST-HPE) with low wind speed in the lower atmosphere, whereas the remaining three HPEs were driven by the combination (hybrid) of both aforementioned systems (HY-HPE). A positive synergistic effect between the HPE and urban heat island (UHI; ∼ 1.1 ∘C increase) was observed in TC-HPE and ST-HPE, whereas no discernible synergistic effect was found in HY-HPE. Total aerosol radiative forcing (TARF) caused a reduction in temperature (0.5–1.0 ∘C) in TC-HPE and ST-HPE but an increase (0.5 ∘C) in HY-HPE.
ISSN:1680-7324
1680-7316
1680-7324
DOI:10.5194/acp-21-13443-2021