1. Update on: 1. Secondary Organic Aerosol 2. Biogenic VOC emissions Colette L. Heald heald@atmos.colostate.edu Chemistry Climate Working Group Meeting February 12, 2008

2. MODELING FRAMEWORK Community Land Model (CLM3) Datasets: Lawrence and Chase [2007] Feddema et al. [2007] LAI (MODIS) Plant Functional Types Soil moisture Vegetation Temperature BVOC Algorithms [Guenther et al., 1995; 2006] Monterpenes: GEIA Isoprene: MEGAN Community Atmospheric Model (CAM3) Chemistry Transport Radiation BVOC Emissions Vegetation Meteorology Radiation Precipitation SOA production Anthropogenic Emissions, GHG concentrations, SST

3. SECONDARY ORGANIC AEROSOL FORMATION Reactive Organic Gases OH, O 3, NO 3 Monoterpenes Aromatics Isoprene OH SOA Condensation of low vapour pressure ROGs on pre- existing aerosol SOA parameterization [Chung and Seinfeld, 2002] VOC i + OXIDANT j   i,j P1 i,j +  i,j P2 i,j Parameters (  ’s K’s) from latest smog chamber studies (Caltech) A i,j G i,j P i,j Equilibrium (Kom i,j )  also f(POA) Y~2-5%Y~15%Y~25%

4. SOA: WHAT IS IN “MY VERSION” OF CAM-CHEM 2-product model SOA 3 classes of SOA (5 tracers): –Monoterpenes (+OH, +O 3, +NO 3 ) [Chung and Seinfeld, 2002] –Isoprene (+OH) [Henze and Seinfeld, 2006] –Aromatics (Benzene, Toluene, Xylene + OH) [Henze et al., 2008] Yields are dynamically NOx dependent Include temperature sensitive partitioning coefficients Iteratively solves for gas-particle equilibrium at every time-step (therefore carry gas phase SOA = SOG as tracers), allows for re- volatilization BOTTOM LINE: addition of SOA/SOG, and rudimentary oxidation scheme for aromatics adds many tracers: –5 SOA, 5 SOG, Xylene/Benzene + oxidation products = 18 CAM-Chem now includes the state of the art for parameterized SOA modeling. PROBLEM: This may not be enough! DISCUSSION: Are simplifications possible to incorporate into Ghan aerosol scheme? Is this desirable?

5. STATUS: BVOC EMISSIONS IN CLM3.5 MONOTERPENES: As in Levis et al. [2003] Based on Guenther et al. [1995] ANNUAL TOT: 43 TgC/yr ISOPRENE: MEGAN v2 [Guenther et al., 2006] (includes T, PAR, soil moisture, LAI, leaf age) ANNUAL TOT: 495 TgC/yr Note: To run with MEGAN2 need new fsurdat file for CLM with isoprene basal emission rates Fluxes passed from CLM  CAM TO DO: Implement MEGAN2 emission factors for 19 other species (monoterpenes, sesquiterpenes, other OVOCs, etc.). Associated changes to chemical mechanism?

6. Several plant growth studies show that isoprene emission is inhibited in a high-CO 2 environment. INHIBITION OF ISOPRENE EMISSION DUE TO CO 2 [Possell et al., 2005] Mick Wilkinson and Russ Monson (UC Boulder) have examined isoprene emission for 4 plant species as a function of both short-term and long- term CO 2 exposure. They have parameterized the observed relationships for one species (aspen) which can be added to the MEGAN v2 activity factors [Wilkinson et al., in prep]. Some preliminary results when implemented in CLM…

7. FOR PRESENT-DAY (2000): EFFECT IS SMALL Annual global total isoprene emissions increase by 7% (from 495 TgC/yr to 530 TgC/yr (mostly in Australia, Amazon)

8. FOR FUTURE (2100 A1B): CO 2 INHIBITION COMPENSATES FOR TEMPERATURE INCREASE Future projected emissions drop from 615 TgC/yr to 506 TgC/yr (again, primarily in Australia and the Amazon) See that ↑in T activity factor ~ compensated by ↓ in CO 2 activity factor Dotted=2000 Solid=2100

9. CONCLUSION: ISOPRENE EMISSIONS PREDICTED TO REMAIN ~CONSTANT Important implications for oxidative environment of the troposphere… [Heald et al., in prep]

11. MEGAN v2 COMPOUNDS Compound/Class Name Class IDEF BT EF NT EF SHR EF GC  Leaf Age CaseLDF Isoprene1map 51 MBO2510080.10.0951 Myrcene32075220.30.0920.05 Sabinene44570500.70.0920.1 limonene545100520.70.0920.05 carene 618160250.30.0920.05 ocimene 790608510.0920.8 pinene 8903001001.50.0920.1 pinene 918045020020.0920.1 farnescene 106030500.90.1530.8 caryophyllene 116075651.20.1530.8 Methanol12400 0.0940 Acetone13100 0.1110 Acetaldehyde and ethanol14120 0.1310 formic acid, formaldehyde, acetic acid1570 0.0910 methane16300 0.0510.75 nitrogen gases: NO, NH3, N2O1755412000.0710 other monoterpenes188718010850.0920.1 other sesquiterpenes1910812510420.1530.8 other VOC20969 0.0910.75