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Update on CAM/CLM Biogenic VOC Emissions and Secondary Organic Aerosols

Update on CAM/CLM Biogenic VOC Emissions and Secondary Organic Aerosols. Colette L. Heald (heald@atmos.berkeley.edu). Chemistry-Climate Working Group Meeting, CCSM February, 2007. THE ROLE OF VOCs IN TROPOSPHERIC CHEMISTRY. h n. O 3. NO 2. NO. VOCs: contribute to O 3 formation

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Update on CAM/CLM Biogenic VOC Emissions and Secondary Organic Aerosols

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  1. Update on CAM/CLM Biogenic VOC Emissions and Secondary Organic Aerosols Colette L. Heald (heald@atmos.berkeley.edu) Chemistry-Climate Working Group Meeting, CCSM February, 2007

  2. THE ROLE OF VOCs IN TROPOSPHERIC CHEMISTRY hn O3 NO2 NO • VOCs: • contribute to O3 formation • ↓OH  ↑GHGs (eg. CH4) • oxidation products can form aerosols SOA OH HO2 CH4, CO, VOC NOx VOC VOC NATURAL ANTHROPOGENIC

  3. PREVIOUS/STANDARD CAM (up to v3.3.41) • Includes Guenther [1995] emissions of monoterpenes and isoprene within CLM  Not passed to CAM chemistry simulation (BVOC are specified) • No aromatic VOC emissions • SOA from monoterpenes only UPDATES: • Implemented MEGAN [Guenther et al., 2006] emission scheme for isoprene in CLM (monoterpene scheme the same at this time) • Emissions passed to CAM • Aromatic VOC emissions (RETRO) and oxidation reactions have been added for SOA scheme • SOA scheme now includes isoprene and aromatics (benzene, toluene, xylene) according to latest yields from the Seinfeld group • Also fixed SOA scheme bug and added T-dependence for yields Note: MEGAN being implemented in standard CAM by Francis Vitt, SOA is still research code (contact Colette Heald for more info)

  4. BVOC EMISSIONS SCHEME Flux = Emission Factor x Activity Factor () SOIL MOISTURE LIGHT TEMPERATURE LEAF AGE ISOPRENE MONTERPENES [Guenther et al., 2006] [Guenther et al., 1995]

  5. PLANT FUNCTION TYPES (PFTs) CLM: 16 PFTs mapped to Guenther et al 6 PFTs Isoprene basal emission factor for each PFT, each gridbox  modulated by local conditions

  6. ANNUAL AVERAGE ISOPRENE EMISSION ACTIVITY FACTORS: 2000

  7. DISTRIBUTION OF BVOC EMISSIONS: 2000 ISOPRENE MONOTERPENES Annual Totals: Isoprene = 558 TgC/yr Monoterpenes = 45 TgC/yr

  8. INTERACTIVE BVOC EMISSIONS  SOA FORMATION Community Land Model (CLM) LAI (MODIS) Plant Functional Types Soil moisture Vegetation Temperature BVOC Algorithms Monterpenes: GEIA Isoprene: MEGAN Vegetation Meteorology BVOC Emissions Radiation Precipitation Community Atmospheric Model (CAM) Chemistry Transport Radiation SOA production

  9. 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 Partition (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 Also include temperature sensitivity: Base case: ΔH = 42 kJ/mol (11-83) Monoterpenes Isoprene Aromatics Y~1-3% Y~5-15% Y~20-50%

  10. SOA (monoterpenes) SOA (isoprene) SOA (aromatics) DJF MAM JJA SON SURFACE SOA CONCENTRATIONS: 2000 TOTAL SOA PRODUCTION = 22 TgC Global Burden: SOA (M): 0.05 TgC SOA (I): 0.40 TgC SOA (A): 0.10 TgC POA: 0.88 TgC Note: monoterpene emissions here are low compared to global estimates (~100 TgC/yr), may expect aromatic SOA to be comparable to monoterpene SOA.

  11. EXTRAS

  12. ISOPRENE: LIGHT AND TEMPERATURE SCALING [Guenther et al., 2006] • LIGHT • Diffuse and direct radiation • Instantaneous and accumulated (24 hrs and 10 days) • TEMPERATURE (Leaf-level) • instantaneous and accumulated (24 hrs, 10 days) T L PAR T

  13. ISOPRENE: SOIL MOISTURE, PHENOLOGY, LAI [Guenther et al., 2006] AMOUNT OF VEGETATION  Leaf area index (LAI) SOIL MOISTURE  suppressed under drought LAI SUMMER Month • LEAF AGE • Max emission = mature • Zero emission = new

  14. MONTERPENES: TEMPERATURE, LAI [Guenther et al., 1995] AMOUNT OF VEGETATION  Leaf area index (LAI) LAI • TEMPERATURE (Leaf-level) • Instantaneous only SUMMER Month T T NO LIGHT dependence Outstanding: dependence onSOIL MOISTUREandLEAF AGE

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