1. Global BVOC Emission Inventories:
A focus on the Southeastern US
Colette L. Heald
Are biogenic emission models sufficient to describe BVOC and oVOC emissions in forested areas, suburban areas, urban areas?
SOAS Workshop
May 25, 2011

2. THE SOUTHEAST IS THE LUSHEST REGION IN THE US
Leaf Area Index (LAI)

3. BIOGENIC VOC EMISSIONS: MEGAN v2
εi is the emission factor at standard conditions for vegetation type i
χi, fractional areal coverage
the emission activity factor
 is the canopy loss and production factor
E=f( )
Baseline emission factors (for some species?) relatively well characterized in the SE…
(I defer to Alex and others…)
[Guenther et al., 2006]

4. UNCERTAINTY ABOUT CURRENT LAND COVER

5. More important than spatial resolution??
HOW DOES UNCERTAINTY IN LAND COVER TRANSLATE TO UNCERTAINTY IN EMISSIONS?
CLM
Guenther
CLM-Guenther
% vegetation cover
Baseline Isoprene Emission Factor
Large uncertainties in BVOC emissions result.
More important than spatial resolution??

6. BVOC EMISSIONS IN THE EASTERN US: MEGAN v2 in CLM
6.8 Tg/yr
0.6 Tg/yr
0.14 Tg/yr
3.2 Tg/yr
Fraction of US BVOC emitted in the SE: ~25% of isoprene, ~15% of MT, ~10% SQ, ~25% oVOC

7. WHAT ABOUT BI-DIRECTIONAL FLUX OF oVOCs?
Fluxes measured at the top of the canopy are NET
Risk that models are effectively double-counting deposition?
Larger issue of evaluating simulated deposition...
And possibly implications of oVOC deposition

8. FUTURE ANTHROPOGENIC LAND USE CHANGE IN THE SE
Anthropogenic land use change is largely the invasion of croplands. In the W US this is at the expense of grasslands, but in the E US also at the expense of trees.
BVOC emissions will decrease in the SE.

9. WHAT ABOUT PLANTATION SPECIES IN THE SOUTHEAST?
Isoprene emissions from oil palm (basal EF: 7.8 mg/m2/h) are 4-8 times the fluxes at a Borneo rainforest.
Also saw higher estragole and lower monoterpenes.
Pictures courtesy: Nick Hewitt

10. NATURAL LAND USE CHANGE ALSO HIGHLY UNCERTAIN
LAI ( )
Same land model (CLM) driven by 8 different climate projections
[Alo and Wang, 2008]
Some key questions:
1. Increase/decrease in precip?
2. How efficient is carbon fertilization?