Organic Carbon Aerosol:An Overview

(and Insight from Recent Field Campaigns)

Colette L. HealdNOAA Climate and Global Change Postdoctoral Fellow

(heald@atmos.berkeley.edu)

*New Affiliation as of Jan 2008*Colorado State University

GEOS-Chem User’s MeetingApril 12, 2007

ORGANIC CARBON AEROSOL

Semi-Volatiles

Oxidation by OH, O3, NO3

Direct Emission

Fossil Fuel Biomass Burning

Terpenes

Nucleation or Condensation

Aromatics

ANTHROPOGENIC SOURCESBIOGENIC SOURCES

Isoprene

Secondary

Organic

Aerosol

Primary

Organic

Aerosol

GEOS-CHEM OC AEROSOL SIMULATION

Semi-Volatiles

Fossil Fuel BiomassBurning

Monoterpenes Aromatics

ANTHROPOGENIC SOURCESBIOGENIC SOURCES

Isoprene

Semi-Volatiles

Fossil Fuel BiomassBurning

Monoterpenes Aromatics

ANTHROPOGENIC SOURCESBIOGENIC SOURCES

Isoprene

Primary Organic Aerosol [Rokjin Park]

FF: Cooke / BondBF: Logan & YevichBB: Duncan

50% hydrophobic, 50% hydrophillic

Secondary Organic Aerosol [Rokjin Park, Hong Liao, Daven Henze]

Terpenes: Chung and Seinfeld [2002]Isoprene: Henze and Seinfeld [2006] (v7.04.05)Aromatics: new smog chamber data (Henze)Heterogeneous Chemistry: glyoxal (May Fu)

SOA treated as hydrophilic, semi-volatile gases are soluble

Empirical parameterization: 2-product model fit to smog chamber studies

VOC + Oxidant α1 P1 + α2 P2

Equilibrium Partitioning Depends on T, [OC]

k1 k2

GLOBAL OC BUDGET IN GEOS-CHEM

SOURCE TgC/yr

Fossil Fuel 10.6

Biofuel 7.6

Biomass Burning ~25

Terpene SOA 9

Isoprene SOA 5.5

Aromatic SOA ~4

Glyoxal/methylglyoxal uptake May’s talk!

[Park et al., 2003; Henze and Seinfeld, 2006]

ORGANIC CARBON AEROSOL: AT THE SURFACE

Organic carbon constitutes 10-70% of aerosol mass at surface.ISSUE: Measurements do not differentiate POA and SOA

2004 NARSTO Assessment

ACE-ASIA: FIRST OC AEROSOL MEASUREMENTS IN THE FREE TROPOSPHERE

Mean ObservationsMean SimulationObservations+

Concentrations of OC in the FT were under-predicted by a factor of 10-100!We conclude this is missing SOA

(ACE-Asia aircraft campaign conducted off of Japan during April/May 2001)

v7.01.02(only terpene SOA)

[Heald et al., 2005]

[Mader et al., 2002] [Huebert et al., 2003] [Maria et al., 2003]

SEVERAL STUDIES SUGGESTING UNDERESTIMATE OF SOA

[Volkamer et al., 2006]

Global underestimate in SOA?

WHAT CONTRIBUTES TO OC AEROSOL OVER NORTH AMERICA?

NOAA WP-3 Flight tracks

OC concentrations in the FT doubled as a result of Alaskan boreal fires.

Observed boreal fireInfluence down-wind

BB filtered using CH3CN

2004: worst fire season on record in Alaska

DO WE UNDERSTAND OC AEROSOL OVER NORTH AMERICA?

Note: biomass burning plumes were removed

OC aerosol concentrations 4x lower than observed off of Asia, model within 25%

BUT we cannot simulate variability in observations (R=0.21) incomplete understanding of formation.

[Heald et al., 2006]

Sulfur Oxides (SOx)Water soluble

OC Aerosol (WSOC)Simulated source

attribution

ObservedSimulated

v7.02.04(includes isoprene SOA)

WHAT DON’T WE UNDERSTAND ABOUT SOA FORMATION?

SVOC

Oxidation by OH, O3, NO3

Direct Emission

Terpenes

Nucleation or Condensation

Aromatics

OC

Isoprene

CloudProcessing

FF: 45-80 TgC/yrBB: 10-30 TgC/yr

SOA: ?? TgC/yr

Fossil Fuel Biomass Burning

ANTHROPOGENIC SOURCESBIOGENIC SOURCES

Heterogeneous ReactionsPRECURSORS

CHEMISTRY1. NOx, SO2/acidity2. Multi-step oxidation

FORMATION PATHWAYS

MODELING OC AEROSOL: FUTURE?

• Better constraints on role of NOx, seed particles, T, RH, and radiative properties

• CMAQ (A. Carlton)

• Example: Donahue volatility basis sets

• Robinson and Donahue suggest

primary aerosol emission is

misconception…

Implementation of smog-chamber results

In-cloud SOA formation

New SOA Schemes?

Semi-volatile primary emissions?

ACKNOWLEDGEMENTS

Daniel Jacob, Rokjin Park, Solène Turquety, Rynda Hudman

Barry HuebertLynn Russell John Seinfeld, Hong Liao

Rodney Weber,Amy SullivanRick Peltier

ITCT-2K4 Science Team

Hosts: Inez Fung & Allen Goldstein