Global BVOC Emission Inventories:A focus on the Southeastern US

Colette L. Heald

SOAS WorkshopMay 25, 2011

Are biogenic emission models sufficient to describe BVOC and oVOC emissions in forested areas, suburban areas, urban areas?

THE SOUTHEAST IS THE LUSHEST REGION IN THE USLeaf Area Index (LAI)

BIOGENIC VOC EMISSIONS: MEGAN v2

i ii

F 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( )

[Guenther et al., 2006]

Baseline emission factors (for some species?) relatively well characterized in the SE…(I defer to Alex and others…)

UNCERTAINTY ABOUT CURRENT LAND COVER

HOW DOES UNCERTAINTY IN LAND COVER TRANSLATE TO UNCERTAINTY IN EMISSIONS?

% vegetation cover

Baseline Isoprene Emission Factor

CLM Guenther CLM-Guenther

Large uncertainties in BVOC emissions result.More important than spatial resolution??

BVOC EMISSIONS IN THE EASTERN US: MEGAN v2 in CLM

Fraction of US BVOC emitted in the SE: ~25% of isoprene, ~15% of MT, ~10% SQ, ~25% oVOC

6.8 Tg/yr

0.6 Tg/yr

0.14 Tg/yr

3.2 Tg/yr

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

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.

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

NATURAL LAND USE CHANGE ALSO HIGHLY UNCERTAIN

LAI (2100-2000)

Some key questions:1. Increase/decrease in precip?2. How efficient is carbon fertilization?

[Alo and Wang, 2008]

Same land model (CLM) driven by 8 different climate

projections