Organic Carbon Aerosol: Insights from the ACE-Asia and ICARTT field campaigns - PowerPoint PPT Presentation

Loading...

PPT – Organic Carbon Aerosol: Insights from the ACE-Asia and ICARTT field campaigns PowerPoint presentation | free to download - id: 1f749b-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Organic Carbon Aerosol: Insights from the ACE-Asia and ICARTT field campaigns

Description:

Daniel J. Jacob, Rokjin J. Park, Sol ne Turquety, Rynda C. Hudman, Rodney J. ... RADIATIVE FORCING OF CLIMATE ... observed at Crater Lake [Jaffe et al., 2005] PACIFIC ... – PowerPoint PPT presentation

Number of Views:29
Avg rating:3.0/5.0
Slides: 30
Provided by: colettel5
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Organic Carbon Aerosol: Insights from the ACE-Asia and ICARTT field campaigns


1
Organic Carbon AerosolInsights from the
ACE-Asia and ICARTT field campaigns
Colette L. Heald (heald_at_atmos.berkeley.edu) Dani
el J. Jacob, Rokjin J. Park, Solène Turquety,
Rynda C. Hudman, Rodney J. Weber, Rick Peltier,
Amy Sullivan, Lynn M. Russell Barry J. Huebert,
John H. Seinfeld, Hong Liao
Stony Brook University April 26, 2006
2
RADIATIVE FORCING OF CLIMATE
Biogenic OC currently not included in forcing
estimates ? is it important?
3
ORGANIC CARBON AEROSOL
Numbers from IPCC 2001
Secondary Organic Aerosol (SOA) 8-40 TgC/yr
Reactive Organic Gases
Nucleation or Condensation
OC
Oxidation by OH, O3, NO3
FF 45-80 TgC/yr BB 10-30 TgC/yr
Monoterpenes
Aromatics
Direct Emission
Fossil Fuel Biomass
Burning
ANTHROPOGENIC SOURCES
BIOGENIC SOURCES
4
MEASURING OC IN THE ATMOSPHERE
CHALLENGE To measure suite of compounds
classified as organic carbon
Filter samples Need to correct for
volatilization of particles (negative artifact)
and adsorption of gas-phase organics (positive
artifact)
Ambient Air
Denuder to remove gas-phase organics
Backup (2) (to capture OC evaporated from
filter 1)
Quartz Filter (1)
Thermal Optical analysis to determine OC
Concentration
5
DISTINGUISHING SOA FROM POA EC/OC RATIO
Example from Pittsburg Air Quality Study Cabada
et al., 2004
EC/OC ratio for primary emissions are
well-correlated (triangles). Deviations from the
slope are indicative of a secondary OC source
(squares).
  • Uncertainties
  • changing EC/OC emission ratios for sources
  • mixing of air masses

6
DISTINGUISHING SOA FROM POAAEROSOL MASS
SPECTROMETER (AMS)
m/z 44 oxygenated organic aerosol ? SOA
m/z 57 hydrocarbon like organic aerosol ? POA
Reduce complexity of observed spectra to 2
signals
2/3 of OC is SOA (in urban site!)
Zhang et al., 2005
7
FIRST SUGGESTIONS OF HIGH ORGANIC CARBON AEROSOL
CONCENTRATIONS IN THE FREE TROPOSPHERE
High organic loading in the FT
High organic loading in the UT
TARFOX (E US) Novakov et al., JGR, 1998
Single particles over NA Murphy et al.,
Science, 1998
8
ACE-ASIA OC AEROSOL MEASUREMENTS IN THE FREE
TROPOSPHERE
(ACE-Asia aircraft campaign conducted off of
Japan during April/May 2001)
Seinfeld group Huebert group Russell
group
High Levels of OC were observed in the FT during
ACE-Asia by 2 independent measurement
techniques. We cannot simulate this OC with
direct emissions
9
DO WE UNDERSTAND OTHER AEROSOLS?
Secondary production
Scavenging
Scavenging
GEOS-Chem simulates both the magnitude and shape
of sulfate and EC concentrations throughout the
troposphere ? what is different about OC?
10
ANY INDICATION THAT DIRECT EMISSIONS ARE
UNDERESTIMATED?
  • Biomass Burning
  • Satellite firecounts show no active fires in
    Siberia
  • OC aerosol from agricultural burning in SE Asia
    emitted earlier in the season, at lower latitudes
    and is not injected into the FT
  • Pollution
  • Although the highest aerosol observations are
    associated with elevated CO, there is a free
    tropospheric background of 1-3 µg sm-3 that is
    not correlated with CO or sulfate.

11
SECONDARY ORGANIC AEROSOL SIMULATION
Secondary Organic Aerosol
SOA parameterization Chung and Seinfeld,
2002 VOCi OXIDANTj ? ai,jP1i,j
ai,jP2i,j Parameters (as Ks) from smog
chamber studies
Condensation of low vapour pressure ROGs on
pre- existing aerosol
Gi,j
Pi,j
Equilibrium (Komi,j) ? also f(POA)
Reactive Organic Gases
Ai,j
Oxidation by OH, O3, NO3
GEOS-CHEM April Biogenic SOA
Biogenic VOCs (eg. monoterpenes)
FT observations 4mg/m3 Biogenic SOA far too
small!
12
IMPLICATIONS FOR TRANSPACIFIC TRANSPORT
NORTH AMERICA
ASIA
PACIFIC
13
CARBON CYCLE AND POTENTIAL RADIATIVE IMPLICATIONS
4 ug/sm3 (ACE-Asia) AOD _at_ 50 RH 0.057 TOA
Radiative Forcing -1.2 W/m2
OC AEROSOL 1 µg/sm3 from 2-7 km globally 105
TgC/yr
DISSOLVED ORGANIC CARBON IN RAINWATER 430 TgC/yr
Wiley et al., 2000
VOC EMISSIONS 500-1000 TgC/yr IPCC, 2001
14
ICARTT COORDINATED ATMOSPHERIC CHEMISTRY
CAMPAIGN OVER EASTERN NORTH AMERICA AND NORTH
ATLANTIC IN SUMMER 2004
  • 2004 fire season in North America
  • worst fire season on record in Alaska

Multi-agency, International Collaboration
Emissions derived from MODIS hot spots Turquety
et al., in prep
MOPITT Observations of CO Transport (July 17-19)
Turquety et al., in prep
OC 1.4 TgC
OC emissions from biomass burning were 4 times
climatological average!
15
UNDERESTIMATE OF OC AEROSOL DURING ICARTT
WSwater soluble (10-80 of total OC, primarily
SOA)
Observed WSOC GEOS-Chem WSOC GEOS-Chem SOA
NOAA ITCT-2K4 flight tracks (R. Webers PILS
instrument aboard)
OC aerosol underestimate observed over North
America as well Heald et al., in prep.
Note biomass burning plumes were removed
16
BIOMASS BURNING INJECTION HEIGHTS
Fires over boreal regions generate enough energy
to inject emissions into FT. Following Turquety
et al. in prep, we inject 60 of emissions
directly into FT (3-5km) thus avoiding
scavenging during lifting.
ITCT-2K4 BB plumes
ITCT-2K4 Background
Observations GEOS-Chem Simulation solid60
injected dashedBL emissions dottedno
BB
Large contribution of WSOC from boreal fires in
plumes and background. Injection of BB emissions
into the FT increases the OC observed in the FT
down-wind. Model may underestimate boreal fires,
or overestimate scavenging or dilution.
17
UNDERESTIMATE AT SURFACE SITES AS WELL
(IMPROVE network established in 1987 to monitor
visibility in national parks)
IMPROVE GEOS-Chem
Sulfate
OC
Uniform 0.9 µgCm-3 underestimate in OC across
the U.S. Smaller contribution from Alaskan
boreal fires at the surface than aloft.
18
INCLUDING ISOPRENE AS A SOURCE OF SOA
Recent study yield of SOA from isoprene is
0.9-3.0Kroll et al., 2005. Isoprene oxidation
products have been observed in the particulate
phase Claeys et al., 2004 Matsunaga et al.,
2005
GEIA Emissions July/August 2004
10 yield 0.8 Tg SOA
3 yield 0.4 Tg SOA
Isoprene is the second most abundant hydrocarbon
emitted to the atmosphere (500 Tg/yr). Even
with a modest yield this could be an
important
source of SOA.
19
INCLUDING ISOPRENE AS A SOURCE OF SOA
COMPARISON WITH ITCT-2K4 OBSERVATIONS
Observed WSOC Simulated WSOC solid SOA
terpenes only dotted SOA
terpenesisoprene Simulated SOA solid SOA
terpenes only dotted SOA terpenesisoprene
Including isoprene as a precursor to SOA
formation (using low NOx yields) leads to modest
increase in SOA simulated over the northeastern
NA.
20
SHARED CHEMICAL ORIGINS OF WSOC?
Correlation Coefficient Matrix
Note BB plumes removed
No single species can explain more than 16 of
the variability in WSOC. Toluene in combination
with other tracers can explain over half the
variability. ? Anthropogenic SOA? ?
21
IS SCAVENGING OF OC AEROSOLS OVERESTIMATED IN
MODELS?
Hydrophillic aerosols are wet scavenged assuming
100 solubility. Recent analysis of cloud events
at Puy de Dome suggest scavenging efficiency of
OC is much lower Sellegri et al.,
2003. However aerosols observed at Jungfraujoch
are internally mixed Baltensperger
ITCT 2K4
Observations GEOS-Chem Simulation dashed
scavenging e0.14 dottted HSOG103-107 M/atm
A large decrease in scavenging efficiency
increases OC throughout the troposphere, however
this assumes a large degree of external mixing.
22
OTHER STUDIES SUGGESTING UNDERESTIMATE OF SOA
ANTHROPOGENIC ORGANIC CARBON BUDGET
Growth in POM larger than decrease In aromatics
The increase in sub-µm POM could not be
explained by the removal of aromatic precursors
alone, suggesting that other species must have
contributed and/or that the mechanism for POM
formation is more efficient than previously
assumed.
de Gouw et al., 2005
23
SMOG CHAMBER STUDIES AMBIENT RELEVANCE
NITROGEN OXIDE LEVELS
TEMPERATURE
Cold Temperature Chemistry
m-xylene photoxidation
decomposition
RO (alkoxy radicals)
aerosol formation?
Add O2
Johnson et al., 2005
Song et al., 2005
m-xylene photoxidation
Terpene ozonolysis
283K
SOA yield at 283K 2x yield at 303K
303K
SOA yields ? zero at VOC/NOx 4.5
Presto et al., 2005
Takekawa et al., 2005
24
FORMATION MECHANISMS FOR ADDITIONAL SOA
OLIGOMERIZATION
CLOUD PROCESSING
2.5 hrs
Evaporation
Oxidation by OH
VOC
TMB
Mechanism for cloud-processing of isoprene has
been demonstrated in the lab.
4.5 hrs
Growth of higher mass
Lim et al., 2005
UPTAKE OF GLYOXAL ON AEROSOLS
6.5 hrs
Polymerization (oligomerization) produces higher
mass compounds with lower vapour pressure ? SOA
Uptake of glyoxal can increase SOA by at least 15
Kalberer et al., 2004
Volkamer et al., 2006
25
CONSTRAINTS FROM SATELLITES?AEROSOL OPTICAL
DEPTHS 2001/2005
MODIS MISR
CAM
Community Atmospheric Model (NCAR ESM with
MOZART chemistry)
Simulated AOD overestimated over land and
underestimated over oceans. Retrieval
uncertainties larger than SOA signal.
MODIS/ MISR
Aerosols
Land (difficult to characterize reflectance)
26
CONSTRAINTS FROM SATELLITES?GLYOXAL AROMATIC
OXIDATION PRODUCT
  • Space-based observations can test
  • Evidence of glyoxal uptake on aerosols?
  • General test on VOC chemistry

Courtesy Rainer Volkamer
27
BEFORE ORGANIC CARBON AEROSOL
Numbers from IPCC 2001
Secondary Organic Aerosol (SOA) 8-40 TgC/yr
Reactive Organic Gases
Nucleation or Condensation
OC
Oxidation by OH, O3, NO3
FF 45-80 TgC/yr BB 10-30 TgC/yr
Monoterpenes
Aromatics
Direct Emission
Fossil Fuel Biomass
Burning
ANTHROPOGENIC SOURCES
BIOGENIC SOURCES
28
ORGANIC CARBON AEROSOL
Cloud Processing
SOA ?? TgC/yr
Nucleation or Condensation
OC
ROG
Heterogeneous Reactions
Oxidation by OH, O3, NO3
FF 45-80 TgC/yr BB 10-30 TgC/yr
Monoterpenes
Aromatics
Isoprene
Direct Emission
Fossil Fuel Biomass
Burning
ANTHROPOGENIC SOURCES
BIOGENIC SOURCES
29
CONCLUSIONS
  • Concentrations observed in the FT off of Asia
    during ACE-Asia were 1-2 orders of magnitude
    greater than simulated.
  • Cannot be reconciled with uncertainties in
    current models
  • Important implications for transpacific transport
  • Concentrations of WSOC observed over NE North
    America during ITCT-2K4 were underestimated by a
    factor of 2
  • Much larger biomass burning influence
  • No clear indication from the observations on the
    source of background OC in the free troposphere ?
    anthropogenic SOA?
  • Uncertainties in sources and sinks can resolve
    the disagreement
  • Processes leading to SOA formation not clearly
    understood and not captured with current model
    parameterizations. Expect that estimates of the
    global source of SOA will be revised upwards.

FUNDING ACKNOWLEDGEMENTS EPA, EPRI, NASA ESS
Fellowship, NOAA Global Climate Change
Postdoctoral Fellowship
About PowerShow.com