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| Titel |
Biomass burning influences on ozone during the SAMBBA aircraft campaign. |
| VerfasserIn |
Tim Keslake, Martyn Chiperfield, Graham Mann, Johannes Flemming, Will Morgan, Eoghan Darbyshire, Sam Remy, Sandip Dhomse, Richard Pope, Carly Reddington |
| 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 |
250151165
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| Publikation (Nr.) |
 EGU/EGU2017-15722.pdf |
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| Zusammenfassung |
| Ozone (O3) is an air pollutant and a greenhouse gas. It is detrimental to human and plant
health, damaging plant stomata and therefore limiting photosynthesis. O3 is both formed and
lost via the interconversion between nitric oxide (NO) and nitrogen dioxide (NO2); the
relative amount of O3 produced depends on the amount of NOx (NO + NO2) and volatile
organic compounds (VOCs), which indirectly compete with O3 to oxidise NO back into
NO2, leading to more O3. The Amazon region has some of the lowest background
O3 levels on the planet (∼20 ppb) and is a NOx-limited environment for ozone
production. During the tropical dry season emissions of NOx and VOCs from both
tropical and savannah fires lead to a large increase in O3mixing ratios over the
Amazon.
With a predicted increase in non-agricultural fire activities, due to a changing climate it is
important to understand how much O3is being formed in the Amazon and the sensitivity of
this to fire and other emissions. The amount of O3 is potentially of additional importance as
the Amazon forest is the largest single land carbon sink on the planet, with an estimated net
annual sink of 2.4 pG C yr−1, which could be limited by O3 plant damage. Despite this,
detailed observation of O3and its precursors in the Amazon have been limited. However, the
SAMBBA field campaign (September- October 2012) provides an opportunity to observe
in-situ O3formation.
The ECMWF C-IFS (Composition Integrated Forecast System) developed under MACC
and continued under CAMS, provides global operational forecasts and re-analyses of
atmospheric composition at high spatial resolution (T255, ∼80km). In this study, we
present results from C-IFS experiments for the SAMBBA period, with and without
composition data assimilation, exploring how well the C-IFS represents biomass
burning influences on O3in the Amazon. The aim is to test our understanding of
O3formation and precursor emissions as well as the capability of the C-IFS for air quality
forecasts.
The flight campaign showed average O3 values of 43 ppb, over tropical vegetation in
the dry season with larger values observed in the upper troposphere during the
wet season (61ppb). The largest surface O3values were observed over the eastern
savannah region (75 ppb), where NOx emissions were most significant. Comparisons
to the C-IFS show that the model persistently underestimated O3value compared
to the in-situ observations (MFB -39%). The bias is thought to be caused by an
underestimation of both fire and lightning NOx emissions in the model. When NOx
emissions are improved by assimilation of OMI satellite NO2 data in the Eastern region,
O3values show a smaller overestimation compared to the observations (MFB 4%). |
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