Aircraft Measurements of Ozone and its Pre-cursors in Wildfires.
Abstract
Tropospheric ozone (O3) can adversely affect human health and environmental ecosystems and it is therefore vitally important to understand its formation pathways from both natural and anthropogenic precursors. Wildfires are an important source of these precursors (both VOCs and NOx) and it is likely that the prevalence of wildfires will increase in a warming climate. Wildfires have been shown to contribute to elevated O3 at air quality monitoring sites, so it is therefore important to better understand the emissions, photochemistry and impacts of these fires. Here we present measurements of O3 and its precursors taken from aircraft flights in wildfires in the Amazon rainforest in Brazil, scrublands in Senegal, wetlands in Uganda and moorland peat fires in the UK.
Measurements of O3, CO, NOx, CH4, CO2, C2H6 and a wide range of VOCs were made from the UK FAAM large research aircraft and including sampling directly in the plume and in more aged background haze. Measurements of a range of O3 enhancement ratios (delta[O3] / delta[CO]) are observed, ranging from 0.05 when sampling within 1-2 hours transport time from the all 4 types of fire, to 0.3 when sampling up to 24 hours away from the Senegalese fires. VOC composition of the plumes is also investigated and ratios of different VOCs to CO are examined in order to derive emission estimates of VOCs from wildfires. OH reactivity and model calculations using the Master Chemical Mechanism in the plumes are used to assess the potential contribution of different VOCs to O3 formation. Measurements of HCHO in the plumes and comparison to those predicted by model calculations are used to assess model performance and hence understanding of the photochemistry within the fire plumes.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A31K2869W
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE