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| Titel |
Modelling of the Effect of Biomass Burning Aerosol in South America |
| VerfasserIn |
Gillian Thornhill, Claire Ryder, Eleanor Highwood, Len Shaffrey |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144426
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| Publikation (Nr.) |
 EGU/EGU2017-8251.pdf |
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| Zusammenfassung |
| Modelling of biomass burning aerosol over S. America was undertaken using the HADGEM3
model in order to investigate the impact of absorbing aerosols on climate, particularly in the
S. American region, as part of the SAMBBA project. The model was run for a 30 year period
with a resolution of N96 (1.25 x 1.875 degrees) and 85 vertical levels, using a bulk aerosol
scheme (CLASSIC).
In order to examine the impacts of biomass burning aerosol on radiative fluxes and
climate, we performed two 30-year climate model runs with high and low emissions
over South America (based on the years 2010 and 2000 respectively). Emissions
outside of S. America are taken as the 1997-2000 mean for both runs. The emissions
are taken from GFED 3.1, and scaled by a factor of 2 in the model. Other aerosol
emissions, sea-surface temperatures and sea-ice are based on monthly climatological
means.
The results for September (the month of greatest emissions) show a reduction in the
clear-sky surface SW radiation of 11.5 Wm−2 for the high emissions case over the area of the
highest AOD compared to the low emissions case, with a corresponding reduction in the
surface temperature of the order of 1 K and surface sensible heat flux of 4.3 Wm−2; the
differences in the latent heat flux are less clearly correlated with the differences in
the AOD spatially, with a smaller reduction of 1.8 Wm−2in the biomass burning
area.
The total cloud fraction also shows a reduction for the high emissions case, as expected
from cloud ‘burn-off’ due to the semi-direct effect, with the greatest effect on the
cloud layer in and just above the aerosol. We also see changes to the low-level
(850mb) circulation, with a strengthening of the low-level jet to the east of the
Andes, together with changes in the positioning of the S. Atlantic high pressure
system.
The results show the predicted effects on the radiation budgets and the semi-direct effect
on the cloud cover; we are continuing to study the detailed effects on cloud cover at different
heights, and effects on the general climate for changes in the biomass burning aerosol burden
for S. America.
This modelling work was undertaken as part of the SAMBBA project, which was a
consortium of several UK and Brazilian universities, and included field measurements,
aircraft observations and climate modelling. |
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