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Update on: 1. Secondary Organic Aerosol 2. Biogenic VOC emissions

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. MODELING FRAMEWORK. Community Land Model (CLM3) Datasets: Lawrence and Chase [2007] Feddema et al . [2007]

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Update on: 1. Secondary Organic Aerosol 2. Biogenic VOC emissions

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  1. Update on:1. Secondary Organic Aerosol2. 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 Vegetation Meteorology BVOC Emissions Radiation Precipitation Community Atmospheric Model (CAM3) Chemistry Transport Radiation SOA production Anthropogenic Emissions, GHG concentrations, SST

  3. SOA parameterization [Chung and Seinfeld, 2002] VOCi + OXIDANTj ai,jP1i,j+ ai,jP2i,j Parameters (a’s K’s) from latest smog chamber studies (Caltech) Gi,j Pi,j Equilibrium (Komi,j)  also f(POA) Ai,j SECONDARY ORGANIC AEROSOL FORMATION SOA Condensation of low vapour pressure ROGs on pre- existing aerosol Reactive Organic Gases OH OH OH, O3, NO3 Monoterpenes Isoprene Aromatics 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, +O3, +NO3) [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 Fluxes passed from CLM  CAM ISOPRENE: MEGAN v2 [Guenther et al., 2006] (includes T, PAR, soil moisture, LAI, leaf age) ANNUAL TOT: 495 TgC/yr MONOTERPENES: As in Levis et al. [2003] Based on Guenther et al. [1995] ANNUAL TOT: 43 TgC/yr Note: To run with MEGAN2 need new fsurdat file for CLM with isoprene basal emission rates TO DO: Implement MEGAN2 emission factors for 19 other species (monoterpenes, sesquiterpenes, other OVOCs, etc.). Associated changes to chemical mechanism?

  6. INHIBITION OF ISOPRENE EMISSION DUE TO CO2 Several plant growth studies show that isoprene emission is inhibited in a high-CO2environment. [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 CO2 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): CO2 INHIBITION COMPENSATES FOR TEMPERATURE INCREASE Future projected emissions drop from 615 TgC/yr to 506 TgC/yr (again, primarily in Australia and the Amazon) Dotted=2000 Solid=2100 See that ↑in T activity factor ~ compensated by ↓ in CO2 activity factor

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

  10. MEGAN v2 COMPOUNDS

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