Recent advances in understanding the characteristics, impacts, and fate of biomass burning emissions...
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- Slide 1
- Recent advances in understanding the characteristics, impacts,
and fate of biomass burning emissions Sonia M. Kreidenweis
Professor Department of Atmospheric Science AP Photo/Ed Andrieski
Second SINO-US Workshop on The Challenges Ahead: Sustainability
Issues at the NEWCAP 8-9 September 2014
- Slide 2
- Fires around the globe (2010)
- Slide 3
- Biomass burning impacts surface dimming solar heating possible
ice nuclei affect cloud albedo Direct impact on climate through
light scattering and absorption decrease snow/ice albedo reduce
cloudiness due to dynamical response to heating Above are for
EMITTED PARTICULATE MATTER effects on tropospheric gas-phase
chemistry also expected affect precipitation?
- Slide 4
- Burning in North America (Image: from van der Werf et al., ACP,
2006) In the U.S., about 2 million acres per year of federal
forests were burned by prescribed fires from 1998 to 2006, in
comparison to around 6 million acres of wildfires (Tian et al.,
ES&T, 2008)
- Slide 5
- From a presentation by Running & Reinhardt,
http://ametsoc.org/atmospolicy/climatebriefing/ Fires projected to
increase Already on rise due to many years of fire suppression
policies in US Pressure to conduct prescribed burns, with resulting
impacts on air quality
- Slide 6
- Agricultural burning in US average interannual variability of
crop residue burning emissions of +/- 10% (McCarty, JAWMA,
2011)
- Slide 7
- Examples of crop burning (AR, CA, FL, ID TX, WA), McCarty et
al., SciTotEnv, 2009
- Slide 8
- Lab studies (FLAME I - IV) USFS / USDA Fire Sciences
Laboratory, Missoula, MT Emission factors Optical properties
Cloud-interaction potential
- Slide 9
- Examples of fuels studied
- Slide 10
- soot organic matter Composition of particles in the lab studies
(Levin et al., JGR, 2010)
- Slide 11
- soot organic matter Composition of particles in the lab studies
Al, Ca largest contributors to ash elements Some fuels produced
surprisingly large mass fractions of INORGANIC species Potassium
salts most common Two fuels had large chloride emissions
- Slide 12
- organic matter Composition of particles in the lab studies Al,
Ca largest contributors to ash elements Some fuels produced
surprisingly large mass fractions of INORGANIC species Potassium
salts most common Two fuels had large chloride emissions
- Slide 13
- SMOLDERINGFLAMING Soot content depends on efficiency of
combustion Fraction of particulate matter that is black carbon
(McMeeking et al., JGR, 2009)
- Slide 14
- Single-scattering albedos (McMeeking et al., JGR, accepted)
Modified combustion efficiencyBlack carbon fraction of aerosol mass
More BC more absorbing (AND depends on fuel)
- Slide 15
- Single-scattering albedos (McMeeking et al., JGR, accepted)
Modified combustion efficiencyBlack carbon fraction of aerosol mass
More BC more absorbing (AND depends on fuel) More efficient more BC
(AND depends on fuel)
- Slide 16
- Brown carbon Processing temperature increases 405 nm: strong
reduction in light absorption with heating 532 nm781 nm
- Slide 17
- Absorption ngstrm exponents Very black smoke: closer to diesel
soot (absorbs over all s) bright smoke: highly reflective in vis,
absorbs strongly at shorts (McMeeking et al., JGR, submitted)
- Slide 18
- Absorption ngstrm exponents Very black smoke: closer to diesel
soot (absorbs over all s) bright smoke: highly reflective in vis,
absorbs strongly at shorts Highlights contrasts between fossil fuel
derived black carbon and light-absorbing aerosol from biomass
burning
- Slide 19
- Brown and black carbon in fog from China Fogwater samples from
Taishan obtained in CSU collaborative study with Shandong U and
Hong Kong Polytechnic; image courtesy Prof. Jeff Collett
- Slide 20
- Brown and black carbon in fog from China Fogwater samples from
Taishan obtained in CSU collaborative study with Shandong U and
Hong Kong Polytechnic; image courtesy Prof. Jeff Collett SOA, brown
carbon Lim et al., 2010 Boris et al., 2014
- Slide 21
- Colorado fire season: Regional smoke resulted in highest
AOD
- Slide 22
- What are the semivolatile components? Increasing vapor
pressure
- Slide 23
- What are the semivolatile components? Increasing vapor pressure
particles gases
- Slide 24
- What are the semivolatile components? Increasing vapor pressure
particles gases Either phase
- Slide 25
- Controlled dilution studies
- Slide 26
- The majority of initial particulate ends up in gas phase after
dilution Large variability in EF ~50% of PM mass is lost in
dilution to ~100 g m -3 Further evaporation below ~100 g m -3 ?
normalized mass fraction remaining [Levin, May et al., in
preparation]
- Slide 27
- What is the fate of these evolved gases? CMU smog chamber
- Slide 28
- New aerosol mass formed (sometimes) Hennigan et al., ACP,
2011
- Slide 29
- Loss of organic aerosol downwind in plume May et al., in prep
[OA] plume [CO] plume Aircraft data, Ft. Jackson burn
- Slide 30
- Loss of organic aerosol downwind in plume May et al., in prep
[OA] plume [CO] plume Aircraft data, Ft. Jackson burn Aerosol was
becoming more oxidized (SOA production?), but loss dominated
- Slide 31
- Conceptual picture new particle formation OZONE FORMATION
Secondary pollutants Primary pollutants
- Slide 32
- Fires influence on photochemistry VOCs NOx O 3 PAN
- Slide 33
- Ozone enhancement from biomass burning? Jaffe and Wigder
(2012): Ozone production from wildfires: A critical review estimate
global wildfires produce approximately 3.5% of all global
tropospheric O 3 production In plumes: observed O 3 / CO range:
-0.1 to 0.9 Interactions of numerous factors including fire
emissions, efficiency of combustion, chemical and photochemical
reactions, and age, aerosol effects on chemistry and radiation, and
local and downwind meteorological patterns
- Slide 34
- Summary Biomass burning is ubiquitous, and increasing globally
wildfires highly variable, agric burning more consistent We are
just beginning to understand what constitutes the semi-volatile
organic emissions, how they react in the atmosphere, and their role
in secondary organic aerosol formation Biomass burning likely plays
a role in N deposition budget The chemistry of the aqueous phase is
likely important, but work on this just beginning More controlled
lab studies needed, plus field work provide data needed by
modelers!