ozone production from wildfires in the west part 1: factors influencing ozone production

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Nicole Wigder Ph.D. Candidate University of Washington, Department of Atmospheric Sciences 5 March 2013

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Ozone Production from Wildfires in the West Part 1: Factors Influencing Ozone Production. Nicole Wigder Ph.D. Candidate University of Washington, Department of Atmospheric Sciences 5 March 2013. Ozone production in wildfire plumes is complex. VOCs & OVOCs + NOx → O 3 downwind transport. - PowerPoint PPT Presentation

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Page 1: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

Nicole WigderPh.D. Candidate

University of Washington, Department of Atmospheric Sciences5 March 2013

Page 2: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

VOCs & OVOCs + NOx → O3

downwind transport

Photo by Jon Hee

• CO• CO2

• VOCs• OVOCs• NOx• PM• CH3CHO• Etc.

Why do some wildfires produce ozone while others do not?

ozone production?

Page 3: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

Normalized Enhancement Ratios allow an analysis of variability that is not influenced by fire size or dilution:

∆O3/∆CO or ∆O3/∆CO2

Page 4: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

Plume Age Mean ∆O3/∆CO (ppbv/ppbv) (# plumes)

Range of ∆O3/∆CO

≤ 1-2 days 0.018 (n=55) -0.032-0.34

2-5 days 0.15 (n=39) -0.07-0.66

≥ 5 days 0.22 (n=29) -0.42-0.93

Boreal/ Temperate

Plume Age Mean ∆O3/∆CO (ppbv/ppbv) (# plumes)

Range of ∆O3/∆CO

≤ 1-2 days 0.14 (n=59) -0.06-0.37

2-5 days 0.35 (n=13) 0.26-0.42

≥ 5 days 0.63 (n=18) 0.19-0.87

Tropics/ Subtropics

Jaffe & Wigder (2012)

Page 5: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

VOCs & OVOCs + NOx O3

Photo credits: NPS, USFS

• Fuel nitrogen content: 0.2 - 4%• Combustion efficiency (smoldering ↔ flaming)• Photochemistry

sunlight

NOx/CO2 emission factors4.8x10-4 – 2.3x10-3 g g-1

Variation by a factor of 5!

Page 6: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

NOx

Aerosol NO3-

HNO3

PAN: temperature dependent reservoir

Within hours: ~40% of NOx → PAN (boreal; Alvarado et al., 2010)~22% of NOx → PAN (temperate; Akagi et al., 2012)

O3

Page 7: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

MBO: research site in central Oregon since 2004

2763 meters a.s.l.

Meteorological parameters, CO, PM1, O3, mercury

2012 fire season: CO2, NOx, NOy, EC/OC

Page 8: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

• multiple chemical & PM measurements

• HYPSLIT backward airmass trajectories

• MODIS near real-time images

• FIRMS fire hotspots (NASA)

COPM

1

O3

Page 9: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

r = 0.65

r = 0.14

Two fire plumes observed at MBO in 2012:

Page 10: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

32 wildfires

13 produced ozone

Wigder et al., submitted to Atmos. Environ.

These 13 fires:

∆O3/∆CO range: 0.01-0.51

Large variation within a small geographic area

MBO

Page 11: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

Wildfire plumes transported < 1 day:

∆O3/∆CO wildfire plumes

∆O3/∆CO wildfire/urban mixed plumes

0.04 (n=2) 0.28 (n=2)

That’s a factor of 7 increase in mixed plumes!

Similar results for Californian plumes (Singh et al., 2012)

Page 12: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

MBO

fire

Page 13: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production
Page 14: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

flaming

smoldering

Page 15: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

975 µg/m3

Photo by Jon Hee

Page 16: Ozone Production from Wildfires  in the West Part 1: Factors Influencing Ozone Production

Wildfire identification easiest using a combination of multiple chemical measurements, satellite data and models

Ozone enhancements not necessarily related to PM enhancements

Large variability in ozone production, even within one biome

Evidence that ozone production affected by:• Combustion efficiency• PM• Transport distance• PAN