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Isolating large-scale smoke impacts on cloud and precipitation processes over the Amazon with convection permitting resolution

Abstract:
Absorbing aerosol from biomass burning impacts the hydrological cycle and radiation fluxes both directly and indirectly via modifications to convective processes and cloud development. Using the ICON model in a regional configuration with 1500 m convection-permitting resolution, we isolate the response of the Amazonian atmosphere to biomass burning smoke via enhanced cloud droplet number concentrations Nd (aerosol-cloud-interactions; ACI) and changes to radiative fluxes (aerosol-radiation-interactions; ARI) over a period of 8 days. We decompose ARI into contributions from reduced shortwave radiation and localized heating of the smoke. We show ARI influences the formation and development of convective cells: surface cooling below the smoke drives suppression of convection that increases with smoke optical depth, whilst the elevated heating promotes initial suppression and subsequent intensification of convection overnight; a corresponding diurnal response (repeating temporal response day-after-day) from high precipitation rates is shown. Enhanced Nd (ACI) perturbs the bulk cloud properties and suppresses low-to-moderate precipitation rates. Both ACI and ARI result in enhanced high-altitude ice clouds that have a strong positive longwave radiative effect. Changes to low-cloud coverage (ARI) and albedo (ACI) drive an overall negative shortwave radiative effect, that slowly increases in magnitude due to a moistening of the boundary layer. The overall net radiative effect is dominated by the enhanced high-altitude clouds, and is sensitive to the plume longevity. The considerable diurnal responses that we simulate cannot be observed by polar orbiting satellites widely used in previous work, highlighting the potential of geostationary satellites to observe large-scale impacts of aerosols on clouds.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1029/2021JD034615

Authors


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Institution:
University of Oxford
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Role:
Author
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Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Atmos Ocean & Planet Physics
Role:
Author
ORCID:
0000-0002-8391-6334


Publisher:
American Geophysical Union
Journal:
Journal of Geophysical Research: Atmospheres More from this journal
Volume:
126
Issue:
13
Article number:
e2021JD034615
Publication date:
2021-06-23
Acceptance date:
2021-06-02
DOI:
EISSN:
2169-8996
ISSN:
2169-897X


Language:
English
Keywords:
Pubs id:
1180033
Local pid:
pubs:1180033
Deposit date:
2021-06-02

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