Update on:1. Secondary Organic Aerosol
2. Biogenic VOC emissions
Colette L. [email protected]
Chemistry Climate Working Group MeetingFebruary 12, 2008
MODELING FRAMEWORK
Community Land Model (CLM3)Datasets: Lawrence and Chase [2007]
Feddema et al. [2007]
LAI (MODIS)Plant Functional Types
Soil moistureVegetation Temperature
BVOC Algorithms[Guenther et al., 1995; 2006]
Monterpenes: GEIAIsoprene: MEGAN
Community Atmospheric Model (CAM3)
ChemistryTransportRadiation
BVOC Emissions
VegetationMeteorology
RadiationPrecipitation
SOA production
AnthropogenicEmissions,
GHG concentrations,SST
SECONDARY ORGANIC AEROSOL FORMATION
Reactive Organic Gases
OH, O3, NO3
Monoterpenes AromaticsIsoprene
OHOH
SOA
Condensation of low vapour pressure
ROGs on pre-existing aerosol
SOA parameterization [Chung and Seinfeld, 2002]
VOCi + OXIDANTj i,jP1i,j + i,jP2i,j
Parameters (’s K’s) from latest smog chamber studies (Caltech)
Ai,j
GGi,ji,j
Pi,jEquilibrium (Komi,j) also f(POA)
Y~2-5% Y~15% Y~25%
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 = 18CAM-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?
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?
Several plant growth studies showthat isoprene emission is inhibited in a high-CO2 environment.
INHIBITION OF ISOPRENE EMISSION DUE TO CO2
[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…
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)
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)
See that ↑in T activity factor ~ compensated by ↓ in CO2 activity factor
Dotted=2000Solid=2100
CONCLUSION: ISOPRENE EMISSIONS PREDICTED TO REMAIN ~CONSTANT
Important implications for oxidative environment of the troposphere…
[Heald et al., in prep]
MEGAN v2 COMPOUNDS
Compound/Class NameClass
ID EFBT EFNT EFSHR EFGC
Leaf Age
Case LDFIsoprene 1 map map map map 5 1MBO 2 5 100 8 0.1 0.09 5 1Myrcene 3 20 75 22 0.3 0.09 2 0.05Sabinene 4 45 70 50 0.7 0.09 2 0.1limonene 5 45 100 52 0.7 0.09 2 0.05carene <3-> 6 18 160 25 0.3 0.09 2 0.05ocimene <trans beta> 7 90 60 85 1 0.09 2 0.8pinene <beta-> 8 90 300 100 1.5 0.09 2 0.1pinene <alpha-> 9 180 450 200 2 0.09 2 0.1farnescene <alpha-> 10 60 30 50 0.9 0.15 3 0.8caryophyllene <beta-> 11 60 75 65 1.2 0.15 3 0.8Methanol 12 400 400 400 400 0.09 4 0Acetone 13 100 100 100 100 0.11 1 0Acetaldehyde and ethanol 14 120 120 120 120 0.13 1 0formic acid, formaldehyde, acetic acid 15 70 70 70 70 0.09 1 0methane 16 300 300 300 300 0.05 1 0.75nitrogen gases: NO, NH3, N2O 17 5 5 41 200 0.07 1 0other monoterpenes 18 87 180 108 5 0.09 2 0.1other sesquiterpenes 19 108 125 104 2 0.15 3 0.8other VOC 20 969 969 969 969 0.09 1 0.75