ozone production in biomass burning...

Ozone Production in Biomass Burning Plumes Douglas Finch Paul Palmer

Introduction Plume Tracking Chemical Pathways Summary

Air Quality - A global problem

• Biomass burning can cause high air pollution events downwind

• What happens as this plume

travels? • What happens when the

plume interacts with other pollutants?

Introduction Plume Tracking Chemical Pathways Summary

Ozone from Wildfires

O3

• NOx and VOCs in different concentration lead to different reactions

• Some plumes have net

production of ozone - some have net loss

• What conditions do these

different scenarios occur in?

O3

O3 O3

O3

VOCs

NOx

• Can we capture the plumes chemistry in the model observed during BORTAS? (See Palmer et al, 2013)

Introduction Plume Tracking Chemical Pathways Summary

Following a Plume

• Run the model with only biomass burning CO • Follow the highest concentration of CO for the ‘centre’ of

the plume

Introduction Plume Tracking Chemical Pathways Summary

Ozone in Wildfire Plume

16th July 17th July 18th July 19th July Time (GMT)

Destruction over night (in N. America)

Peak ozone midday

Rapid destruction + jump in plume tracking (not perfect…)

Minor fluctuations - other factors coming into play like biogenic sources?

Ozo

ne (p

pb)

0 40

80

Introduction Plume Tracking Chemical Pathways Summary

Production of Ozone

NO2 + hv

O3

NO + O*

O* + O2

99.9% of all ozone production in the plume

=

NO2 is the controlling factor - what reactions create NO2?

Introduction Plume Tracking Chemical Pathways Summary

Production of NO2

Contribution to NO2

86.7 % NO + O3

Others 13.3%

89 reactions in GEOS-Chem that produce NO2

Introduction Plume Tracking Chemical Pathways Summary

Production of HO2

O3

NO2 + hv

HO2 + O3

CO + OH

Contribution to HO2 Reaction Pathway

99.9 %

4.9%

29.4%

1.4% of ozone was created through this chemical pathway

Introduction Plume Tracking Chemical Pathways Summary

% C

ontri

butio

n

Time since emission

Production of NO2 - Hourly

16th July 17th July 18th July 19th July

0 10

0 50

Introduction Plume Tracking Chemical Pathways Summary

Next Steps

• Look further down the chemical pathways - what species are the big players?

• Do the same for loss reactions • When do different emissions have the biggest

impact? • What does this mean for total reaction yield, not

just percentage contribution?

Delve Deeper…

1

Introduction Plume Tracking Chemical Pathways Summary

Next Steps

• Change biomass, biogenic and anthropogenic emissions one by one and in tandem

• Change in ozone will be tiny - will the change in reactions be larger?

• Do different emissions have different effects at later stages in the plume?

Sensitivity Analysis

2

Introduction Plume Tracking Chemical Pathways Summary

Next Steps

• How will increasing the number of species & reactions impact the ozone?

• Will an updated mechanism change what reaction pathways are important?

• Is the current mechanism getting the right answer for the wrong reasons?

A New Chemical Mechanism (CRI)

3

Introduction Plume Tracking Chemical Pathways Summary

Summary

• BB has been found to cause both production and loss of ozone

• Examining the chemical pathways along a plume track

can give us new insights

• We can quantify the reaction yield from certain pathways - eventually from volume of emission to amount of ozone

• We can determine when the different emission are most

important as the plume travels