Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires
Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These “fire aerosols” can...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/14495/2016/acp-16-14495-2016.pdf |
| Summary: | Open-burning fires play an important role in the earth's climate system. In
addition to contributing a substantial fraction of global emissions of carbon
dioxide, they are a major source of atmospheric aerosols containing
organic carbon, black carbon, and sulfate. These “fire aerosols” can
influence the climate via direct and indirect radiative effects. In this
study, we investigate these radiative effects and the hydrological fast
response using the Community Atmosphere Model version 5 (CAM5). Emissions of
fire aerosols exert a global mean net radiative effect of
−1.0 W m<sup>−2</sup>, dominated by the cloud shortwave response to organic
carbon aerosol. The net radiative effect is particularly strong over boreal
regions. Conventionally, many climate modelling studies have used an
interannually invariant monthly climatology of emissions of fire aerosols.
However, by comparing simulations using interannually varying emissions vs.
interannually invariant emissions, we find that ignoring the interannual
variability of the emissions can lead to systematic overestimation of the
strength of the net radiative effect of the fire aerosols. Globally, the
overestimation is +23 % (−0.2 W m<sup>−2</sup>). Regionally, the
overestimation can be substantially larger. For example, over Australia and
New Zealand the overestimation is +58 % (−1.2 W m<sup>−2</sup>), while over
Boreal Asia the overestimation is +43 % (−1.9 W m<sup>−2</sup>). The
systematic overestimation of the net radiative effect of the fire aerosols is
likely due to the non-linear influence of aerosols on clouds. However,
ignoring interannual variability in the emissions does not appear to
significantly impact the hydrological fast response. In order to improve
understanding of the climate system, we need to take into account the
interannual variability of aerosol emissions. |
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| ISSN: | 1680-7316 1680-7324 |