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Biogenic Emissions of Organics: Global Budgets and Implications. Colette L. Heald Russ Monson, Mick Wilkinson, Clement Alo, Guiling Wang, Alex Guenther Scot Martin, Qi Chen, Jose Jimenez, Delphine Farmer. IGAC Conference, Annecy, France September 11, 2008. - PowerPoint PPT Presentation
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Biogenic Emissions of Organics:Global Budgets and Implications
IGAC Conference, Annecy, FranceSeptember 11, 2008
Colette L. Heald
Russ Monson, Mick Wilkinson, Clement Alo, Guiling Wang, Alex GuentherScot Martin, Qi Chen, Jose Jimenez, Delphine Farmer
ISOPRENE: CONTROLLING AIR QUALITY AND CLIMATE
C5 H8: Reactive hydrocarbon emitted from plants (primarily broadleaf trees)
Annual global emissions ~ equivalent to methane emissions
+ OH
O3
Depletes OH = ↑ CH4 lifetime
IPCC, 2007Beijing
CLIMATE
AIR QUALITY
METEOROLOGICAL AND PHENOLOGICAL VARIABLES CONTROLLING ISOPRENE EMISSION
LIGHTDiffuse and direct radiationInstantaneous and accumulated (24 hrs and 10 days)
TEMPERATURE (Leaf-level)instantaneous and accumulated (24 hrs, 10 days)
TPAR
L
T
[Guenther et al., 2006]SOIL MOISTURE suppressed under drought
AMOUNT OF VEGETATION Leaf area index (LAI)
Month
LAISUMMER
LEAF AGEMax emission = mature Zero emission = new
ISOPRENE IN THE FUTURE
Isoprene emissions projected to increase substantially due to warmer climate and increasing vegetation density.
LARGE impact on oxidant chemistry and climate
2000 2100
NPP ↑ Temperature↑
Surface O3 ↑ 10-30 ppb [Sanderson et al., 2003]
Methane lifetime increases[Shindell et al., 2007] SOA burden ↑ > 20%
[Heald et al., 2008]
A MISSING FACTOR: ISOPRENE EMISSION INHIBITION BY CO2
Long-Term growth environment: gene adaptationDependent on ambient CO2
Short-term exposure: changes in metabolite pools and enzyme activityDependent on intercellular CO2
Empirical parameterization from plant studies [Wilkinson et al., GCB, accepted]
To what degree does this CO2 inhibition counteract predicted increases in
isoprene (due to T and NPP)?
2100 (A1B): CO2 INHIBITION COMPENSATES FOR TEMPERATURE INCREASE
See that ↑in T activity factor ~ compensated by ↓ in CO2 activity factor
696 TgC/yr
Isoprene emissions in 2100Decrease when CO2 inhibition
included
31%
Dotted=2000Solid=2100
Global Model: NCAR CAM3-CLM3 (2x2.5)
CONCLUSION: ISOPRENE EMISSIONS PREDICTED TO REMAIN ~CONSTANT
Important implications for oxidative environment of the troposphere…
* With fixed vegetation
508 523
696
479
Eisop (TgCyr-1)
2000 2100 (A1B)
MEGANMEGAN with CO2 inhibition
UNLESS…CO2 FERTILIZATION IS STRONG
CLM DGVM projects a 3x increase in LAI associated with NPP and a northward expansion of vegetation.
[Alo and Wang, 2008]
Isoprene emissions more than double! (1242 TgCyr-1)
BUT, recent work suggests that NPP increases may be
overestimated by 74% when neglecting the role of
nutrient limitation [Thornton et al., 2007]
[Heald et al., GCB, accepted]
PRIMARY BIOLOGICAL AEROSOL PARTICLES (PBAP)
POLLEN
BACTERIA VIRUSES
FUNGUS
ALGAEPLANTDEBRIS
How much does this source contribute to sub-micron OC?
Jaenicke [2005] suggests may be as large a source as dust/sea salt (1000s Tg/yr)Elbert et al. [2007] suggest emission of fungal spores ~ 50 Tg/yr
LARGE particles (> 10 µm)
PRELIMINARY EMPIRICAL PBAP SIMULATIONBased on Elbert et al. [2007] who summarize observed PBAP concentrations and
estimate 50 Tg/yr of fungal spores emitted over entire size range.
Global Annual Mean Burden
1.4
1.0
POA SOA PBAPfine
PBAPint
< 1 m 1-3 m
Tg
0.150.03
Global Model: GEOS-Chem (2x2.5)
Surface: June
? ?
ANY INDICATION OF PBAP IN AMAZE-08?
**PRELIMINARY AMS obs: Scot Martin, Qi Chen (Harvard). Jose Jimenez, Delphine Farmer (CU Boulder)
SIMULATED OC
Early Feb: Fire influence
Field site: close to Manaus, Brazil (in Amazonia), Feb-Mar
No obvious indication of an important sub-micron PBAP in the “pristine” Amazon…
What about “intermediate” size range??
NEED: (1) better understanding of emission drivers(2) More observations of PBAP