Update on:1. Secondary Organic Aerosol

2. Biogenic VOC emissions

Colette L. Healdheald@atmos.colostate.edu

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