Anthropogenic Air Pollution Delays Marine Stratocumulus Breakup to Open Cells

Marine stratocumulus cloud (Sc) decks with high cloud fraction typically breakup when sufficient drizzle forms. Cloud breakup leads to a lower cloud radiative effect due to the lower cloud amount. Here we use realistic Lagrangian large eddy simulations along a 3‐day trajectory, evaluated with satell...

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Veröffentlicht in:Geophysical research letters Jg. 46; H. 23; S. 14135 - 14144
Hauptverfasser: Goren, Tom, Kazil, Jan, Hoffmann, Fabian, Yamaguchi, Takanobu, Feingold, Graham
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Washington John Wiley & Sons, Inc 16.12.2019
Schlagworte:
Aerosol concentrations
Aerosol effects
Aerosols
Aerosol‐cloud interaction
Air pollution
Albedo
Anthropogenic air‐pollution
Anthropogenic factors
Breakup
Cloud albedo
Cloud amount
Cloud cover
Cloud transitions
Cloudiness
Clouds
Decks
Diurnal
Diurnal cycle
Diurnal variations
Drizzle
Human influences
Large eddy simulation
Large eddy simulations
Marine pollution
Marine stratocumulus clouds
Meteorology
Radiative forcing
Satellite observation
Stratocumulus clouds
Trajectory analysis
ISSN:0094-8276, 1944-8007
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Zusammenfassung:Marine stratocumulus cloud (Sc) decks with high cloud fraction typically breakup when sufficient drizzle forms. Cloud breakup leads to a lower cloud radiative effect due to the lower cloud amount. Here we use realistic Lagrangian large eddy simulations along a 3‐day trajectory, evaluated with satellite observations, to investigate the timing of Sc breakup in response to aerosol conditions. We show that the timing of the breakup is strongly modulated by the diurnal cycle and large‐scale meteorology but varies systematically with the initial aerosol concentration: the more polluted the clouds, the later the breakup. This indicates that the cloud radiative effect via cloud cover adjustments is not saturated, in contrast to the effect of aerosol on cloud albedo at fixed cloudiness, which weakens with increasing aerosol levels. The results also show that the cloud radiative impact of anthropogenic aerosol is strongest far from its origin over land. Key Points Marine stratocumulus cloud breakup time is systematically delayed with increasing initial background aerosol concentration Cloud cover response to aerosol is not saturated, in contrast to the effect of aerosol on cloud albedo at fixed cloudiness Realistic Lagrangian large eddy simulations identify the roles of both aerosol and meteorology in determining cloud breakup time
Bibliographie:ObjectType-Article-1
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content type line 14
ISSN:0094-8276
1944-8007
DOI:10.1029/2019GL085412