GLOBAL CONSTRAINTS ON BIOGENIC VOC EMISSIONS FROM ATMOSPHERIC OBSERVATIONS

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GLOBAL CONSTRAINTS ON BIOGENIC VOC EMISSIONS
FROM ATMOSPHERIC OBSERVATIONS
Daniel J. Jacob with Paul I. Palmer, Dorian S.
Abbot, May Fu, Brendan Field, Mat J. Evans,
Yaping Xiao
and Randall V. Martin (Dalhousie U. ), Kelly V.
Chance (Harvard-Smithsonian), Hanwant B. Singh
(NASA-Ames), Joost DeGouw (NOAA/AL), Armin Hansel
(U. Innsbruck), Don Blake (UCI), Nicholas Jones
(U. Woolagong)
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PART1 MAPPING OF ISOPRENE EMISSIONS USING
HCHO COLUMN MEASUREMENTS FROM SPACE
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SPACE-BASED MEASUREMENTS OF HCHO COLUMNSAS
CONSTRAINTS ON VOC EMISSIONS
340 nm
hn (l lt 345 nm), OH
Oxidation (OH, O3, NO3)
VOC
HCHO
lifetime of hours
many steps
Emissions
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MEASUREMENT OF HCHO COLUMNS FROM THE GOME
SATELLITE INSTRUMENT(P.I. John Burrows)

• HCHO column is determined from backscattered
  solar radiance in 340 nm absorption band
• Instrument is in polar sun-synchronous orbit,
  1030 a.m. observation time
• 320x40 km2 field of view, three cross-track
  scenes
• Complete global coverage in 3 days
• Operational since 1995

Expect higher-resolution measurements soon from
SCIAMACHY (30x60 km2, launched 2002) and OMI
(13x24 km2, to be launched in June)
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RETRIEVING SLANT COLUMNS FROM SOLAR BACKSCATTER
MEASUREMENTS
absorption
Backscattered intensity IB
l1
l2
wavelength
Slant optical depth
Slant column
Scattering by Earth surface and by atmosphere
EARTH SURFACE
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FITTING OF HCHO SLANT COLUMNS FROM GOME SPECTRA
Chance et al., 2000
ts 1.0 0.3 x1016 cm-2
Fitting uncertainty of 4x1015 molecules
cm-3 corresponds to 1 ppbv HCHO in lowest 2 km
ts 3.0 0.4 x1016 cm-2
ts 8.4 0.7 x1016 cm-2
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HCHO SLANT COLUMNS MEASURED BY GOME (JULY 1996)
2.5x1016 molecules cm-2
2
1.5
1
0.5
South Atlantic Anomaly (disregard)
0
-0.5
High HCHO regions reflect VOC emissions from
fires, biosphere, human activity
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AIR MASS FACTOR (AMF) CONVERTS SLANT COLUMN WS
TO VERTICAL COLUMN W
Geometric AMF (AMFG) for non-scattering
atmosphere
EARTH SURFACE
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IN SCATTERING ATMOSPHERE, AMF DEPENDS ON VERTICAL
DISTRIBUTION OF ABSORBER
HCHO
Use GEOS-CHEM chemical transport model to specify
shape of vertical profile for given scene
Observations (Y.N. Lee)
Model
SOS (southeast U.S., Jul 1995)
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AMF CALCULATION FOR SCATTERING ATMOSPHERE
GOME sensitivity f (sun angle, albedo,
aerosols, cloud)
Vertical concentration profile shape factor
(normalized)
Geometric AMF
ATMOSPHERIC CHEMISTRY MODEL (GEOS-CHEM)
RADIATIVE TRANSFER MODEL
From GOME
Slant column
Vertical column
AMF
From model
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ILLUSTRATIVE PROFILE FOR SCENE OVER TENNESSEE
AMFG 2.08 actual AMF 0.71
what GOME sees
GOME sensitivity w(z)
HCHO mixing ratio profile S(z) (GEOS-CHEM)
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FORMALDEHYDE COLUMNS FROM GOME July 1996 means
compare to GEOS-CHEM including GEIA biogenic
VOC emissions and EPA anthropogenic VOC
emissions GEOS-CHEM vs. GOME R 0.83, bias
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RELATING HCHO COLUMNS TO VOC EMISSION
hn (340 nm), OH
oxn.
VOCi
HCHO
yield yi
k 0.5 h-1
Emission Ei
smearing, displacement
In absence of horizontal wind, mass balance for
HCHO column WHCHO
Local linear relationship between HCHO and E
but wind smears this local relationship between
WHCHO and Ei depending on the lifetime of the
parent VOC with respect to HCHO production
Isoprene
WHCHO
a-pinene
propane
Distance downwind
100 km
VOC source
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SEASONALITY OF GOME HCHO COLUMNS
(9/96-8/97)Largely reflects seasonality of
isoprene emissionsgeneral consistency with GEIA
but also some notable differences
GOME GEOS-CHEM (GEIA)
GOME GEOS-CHEM (GEIA)
JUL
MAR
AUG
APR
SEP
MAY
JUN
OCT
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INTERANNUAL VARIABILITY OF GOME HCHO COLUMNS
Augusts 1995-2001 correlation with temperature
anomaly explains some but not all of the HCHO
column variability
GOME HCHO Temp. anomaly
GOME HCHO Temp. anomaly
1995
1999
1996
2000
2001
1997
1998
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OZARKS ISOPRENE VOLCANO AS SEEN BY GOME(but
not always)
GOME HCHO columns over the Ozarks, July 1996
daily orbits and relationship to temperature
Temperature dependence of isoprene emission (GEIA)
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ULTIMATE YIELD OF HCHO FROM ISOPRENE
Uncertainty in peroxide recycling under low-NOx
conditions
OH
.OO
HO2
NO
hn,OH
HCHO, MVK, MACR
HOO
?
Isoprene peroxides are recycled in GEOS-CHEM
(consistent with MCM)
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HCHO COLUMN vs. ISOPRENE EMISSION RELATIONSHIPIN
GEOS-CHEM MODEL
Results for U.S. quadrants in July 1996
simulation w/ 2ox2.5o horizontal resolution show
(1) dominance of isoprene emission as predictor
of WHCHO variability (2) linear
relationship between the two
Standard simulation
NW
NE
R2 0.43
HCHO from simulation w/o Isoprene emission
R2 0.51
Model HCHO column 1016 molec cm-2
R2 0.65
SE
SW
R2 0.49
We use this relationship to derive top-down
isoprene emissions from the GOME HCHO column
observations
Isoprene emission 1013 atomC cm-2 s-1
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ISOPRENE EMISSION INVENTORIES, JULY1996
GOME top-down (5.7 Tg)
GEIA (7.1 Tg)
BEIS2 (2.6 Tg)
Paui Palmer to show comparisons to MEGAN
inventory Wednesday
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MODEL vs. OBSERVED SURFACE HCHO
Mean daytime HCHO observations Jun-Aug 1988-1998
GEOS-CHEM simulation with GOME isoprene
emissions
high outliers
GOME isoprene emission inventory gives better fit
to surface HCHO data than either GEIA or BEIS2
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WHAT ABOUT THE REST OF THE WORLD?
Were starting to look at China
GOME (July 1997)
GEOS-CHEM using GEIA (July 1997)
High emissions from forests in NE China? Need to
be careful about possible fire influence
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PART 2GLOBAL BUDGET OF METHANOL
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GLOBAL GEOS-CHEM BUDGET OF METHANOL (Tg
yr-1)with (in parentheses) ranges of previous
budgets from Singh et al. 2000,Heikes et al.
2002, Galbally and Kirstine 2003, Tie et al.
2003
CH3O2 (85) RO2 (15)
OH
CH3OH lifetime 10 days (5-12)
130
VOC
CH3O2
Atmospheric production 37(18-31)
OH(aq) - clouds
lt1 (5-10)
Dry dep. (land) 56 Wet dep. 12
NPP based, x3 for young leaves
Ocean uptake 11 (0-50)
Plant growth 128 (50-312)
Biomass burning 9 (6-13) Biofuels 3
Urban 4 (3-8)
Plant decay 23 (13-20)
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SIMULATED METHANOL CONCENTRATIONS IN SURFACE AIR

• Representative observations
• In ppbv Heikes et al., 2002
• Urban 20 (lt1-47)
• Forests 10 (1-37)
• Grasslands 6 (4-9)
• cont. background 2 (1-4)
• NH oceans 0.9 (0.3-1.4)

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METHANOL-CO RELATIONSHIP OVER N. INDIAN OCEAN
INDOEX cruise Wisthaler et al., 2002
Small dots obs Large dots model
Positive correlation reflects outflow from India,
where CO is mainly from combustion and methanol
mostly from terrestrial biosphere
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METHANOL IN ASIAN OUTFLOW OVER PACIFIC
TRACE-P campaign, March-April 2001
Observed H.B. Singh Model Plant growth
tracer Biomass burning tracer
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METHANOL AT NORTH AMERICAN HIGH LATITUDES (TOPSE
MISSION) MODEL (red) vs. OBSERVED (black)
Observations from D.R. Blake (U.C. Irvine)
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METHANOL VERTICAL PROFILES OVER S. PACIFIC
obs. From H.B. Singh
Could the atmospheric source from CH3O2 CH3O2
be underestimated?
HO2
CH3OOH
70
OH
In model over S. Pacific,
NO
CH4
CH3O2
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HCHO
CH3O2
5-10
0.6 CH3OH
Photochemical model calculations for same data
set Olson et al., 2001 are 50 too high for
CH3OOH, factor of 2 too low for HCHO
Could there be a biogenic VOC soup driving
organic and HOx chemistry in the remote
troposphere?
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PART 3ACETONE. ACETALDEHYDE, HCN
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GLOBAL GEOS-CHEM BUDGET OF ACETONE (Tg yr-1)from
Jacob et al. 2002 with photolysis update from
Blitz et al. 2004
hn
propane i-butane
OH
(CH3)2CO lifetime 15 days 18 days
46
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21 (16-26)
OH
OH, O3
terpenes MBO
7 (3-11)
27
37
Dry dep. (land) 9
12
Ocean uptake 14 19
Ocean source 27 (21-33)
microbes
DOChv
Vegetation 33 (22-42)
Biomass burning 5 (3-7)
Urban 1 (1-2)
Plant decay 2 (-3 - 7)
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OCEANIC SOURCE OF ACETONE IN MODELNEEDED TO
MATCH OBSERVATIONS OVER S. PACIFIC
from Jacob et al. 2002
obs from Solberg et al. 1996
obs. From H.B. Singh
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MORE RECENT AIRCRAFT DATA IMPLY A NET OCEANIC
SINK FOR ACETONE
TRACE-P observations over tropical North Pacific
in spring Singh et al., 2003
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CORRELATION OF ACETONE WITH TRACERS OF SOURCES IN
ASIAN OUTFLOW (TRACE-P DATA)
Multiple regression
Continental source
Propane source
Acetone b0 b1 Ethane b2 HCN b3
Methanol
Acetone pptv
Acetone pptv
Intercept 200 pptv
CO pptv
Ethane pptv
Acetone b0 b1 CO b2 HCN b3
Methanol
Biomass burning source
Acetone pptv
Acetone pptv
Biogenic source
Intercept 238 pptv
How to explain the pervasive 200 pptv acetone
background?
Methanol pptv
HCN pptv
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HIGH CONCENTRATIONS OF ALDEHYDES OVER REMOTE
NORTH PACIFIC
Singh et al. 2003
Inconsistent with observed PAN/NOx Staudt et
al., 2003
Also inconsistent with observed PAN/PPN 100!
HOW RELIABLE ARE THE OBSERVATIONS?
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GLOBAL GEOS-CHEM BUDGET OF HCN (Tg N yr-1)from
Li et al. 2003
HCN lifetime 5 mos.
OH
0.1
Ocean uptake 0.73
Residential fuel 0.2
HCN(aq)/CN-
Vegetation ?
Biomass burning 0.63
3 mos.
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FTIR SURFACE-BASED MEASUREMENTS OF HCN COLUMNS
Lines are model values
Japan
Kitt Peak
Spitzbergen
Jungfraujoch
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CONFIRMATION OF BIOMASS BURNING SOURCE, OCEAN
SINK IN TRACE-P AIRCRAFT DATA
Mean vertical profile over remote N. Pacific
Correlation with CO
Li et al. 2003 HCN observations from H.B.
SIngh
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SIMULATED GLOBAL DISTRIBUTION OF HCNLi et al.,
2003
Lauder
Neumayer
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BUT MODEL UNDERESTIMATES RECENT HCN COLUMN
OBSERVATIONS AT NEUMAYER
Southern Ocean is not a sink for HCN
compensation point?
Obs, Neumayer (N. Jones)
Obs, Lauder (C. Rinsland)
Model, Neumayer
Model, Lauder
Need better understanding of HCN(aq)/CN-
chemistry in ocean and of role of terrestrial
biosphere in HCN budget