Transcript Cambridge seminar

North American
Hydrocarbon Emissions
Measured from Space
Paul Palmer
Division of Engineering and Applied Sciences
Harvard University
http://www.people.fas.harvard.edu/~ppalmer
Talk Overview
• Why are accurate hydrocarbon
emissions important?
•How is it possible to relate measured
HCHO columns to specific hydrocarbon
emissions?
•Are satellite observations consistent
with in situ data?
•The future?
O3
hv
O2
STRATOSPHERE
hv
O3
hv, H2O
OH
NO2
NO
OH
HO2
TROPOSPHERE
HNO3
H2O2
CO, hydrocarbons, NOx
HCHO + h  2HO2 + CO
(radical channel)
HCHO + OH  HO2 + CO + H2O
lifetime = few hrs
How do we validate satellite
observations?
GOME,
MOPITT,
SCIAMACHY
TES, OMI
Global 3d model
of chemistry
Summertime in situ HCHO
datasets
Fried et al 1997
Harris et al 1989
Kleindienst et al 1988
Lee et al 1995, 1998
Martin et al 1991
McKeen et al 1997
OZIE -Guenther
Reimer et al 1998
Shepson et al 1991
ppb
Aircraft HCHO profile data
North Atlantic Regional
Experiment 1997
Southern Oxidant Study 1995
Altitude [km]
Altitude [km]
measurements
GEOS-CHEM model
[ppb]
Continental outflow
Surface source (mostly
isoprene+OH)
Relating HCHO columns to
hydrocarbon emissions
Chemical loss kHCHO
HCHO 
HC oxidation
ki (HCHO
Emission Ei
yield Yi)
HCi
•Absence of transport
 = i Yi Ei
kHCHO
HCHO yields from HCs
Species Emission
HCHO Yield
[TgC month-1] [C-1]
CH4
2.6
1.0
Potential HCHO
production [%]
28.5
ISOP
7.3
0.45
32.0
 pinenes
MBO
1.1
0.8
0.8
0.019
0.045
0.06
0.23
0.39
0.53
HCHO
0.15
1.0
1.64
CH3OH
2.1
1.0
23.0
Total:
86%
Horizontal transport displaces HCHO signal
Displacement length scale
L d,i =
ki
U
ln(
)
ki -kHCHO
kHCHO
midmorning eg values
KHCHO = 0.5h-1; U = 20kmh-1; [OH]=5E6 mol cm-3
ISOP
Ld,i  40 km
CH4
Ld,i = many 1000s km
CH3OH Ld,i =100s km
GEOS-CHEM global
3D model: 101
•Driven by DAO GEOS met data
o
•2x2.5 resolution/26 vertical levels
•O3-NOx-VOC chemistry
•GEIA isoprene emissions
•Aerosol scattering: AOD:O3
Dickerson et al, [1997]
GEIA isoprene
emissions
GEOS-CHEM
HCHO
columns
July 1996
[1016 molec cm-2]
Model HCHO column [1016 molec cm-2]
July 1996 (25-50oN, 65-130oW)
NW
NE
Slope S = Y/kHCHO
SW
SE
model without isoprene
Isoprene emission [1013 atomC cm-2 s-1]
n
S
[103 s]
r2

lifetime
[hours]
Y
[C-1]
NW 1810 2.04
0.51 1.67
0.34
NE
2193 1.90
0.43 1.76
0.30
SE
1913 2.09
0.65 1.48
0.39
SW 1750 1.27
0.49 1.48
0.24
Yields consistent with photochemical model
Global Ozone Monitoring
Experiment
• Nadir-viewing SBUV instrument
• Launched April 1995
• Pixel 320 x 40 km2
• 10.30 am cross-equator time
• Global coverage in 3 days
• O3, NO2, BrO, OClO, SO2, HCHO, H2O, &
cloud coverage
HCHO columns – July 1996
GEOS-CHEM
r2 = 0.7
n = 756
Bias = 11%
[1016molec cm-2]
GOME
HCHO fitted in UV
(~340 nm)
1 uncertainty:
4 x 1015 molec cm-2
GOME
Isoprene “volcano”
GEOS-CHEM
July 7 1996
July 20 1996
[1016 molec cm-2]
mm
The Ozarks
• Dissected plateau - 129,500 sq km
• Oak forests – good isoprene emitters
Cambridge, MA
"Trees cause more pollution than automobiles do."
Ozark Isoprene Experiment 1998
Enclosure measurements
Result Summary
Type
Balloon-borne
measurements
Photos c/o Alex
Guenther, NCAR
Spec ppb
Alt [m]
Local time
Balloon Isop
1-7
400-1000 0830-1930
Plane
3-6
450-900 1800-2000
Isop
Surface HCHO 7-15(11)
0830-1930
Plane
1300-1800
HCHO 3-11(7)
HCHO data over the Ozarks
SOS 1999
Aircraft data @ 350 m during July 1999
Illinois
Missouri
Kansas
OZARKS
[ppb]
c/o Y-N. Lee, Brookhaven National Lab.
Isoprene “volcano”GEOS-CHEM
July 7 1996
Slant column HCHO [1016 mol cm-2]
GOME
Temperature dependence of
isoprene emission
Surface temperature [K]
July 20 1996
[1016 molec cm-2]
Global 3d model
of chemistry
GEIA
EPA
BEIS2
Summertime in situ HCHO
datasets
Fried et al 1997
Harris et al 1989
Kleindienst et al 1988
Lee et al 1995, 1998
Martin et al 1991
McKeen et al 1997
OZIE -Guenther
Reimer et al 1998
Shepson et al 1991
ppb
Modeling in situ data
GEIA
r2 = 0.53
BEIS2
r2 = 0.65
Bias -3%
Bias -30%
Model HCHO column [1016 molec cm-2]
Model Transfer functions
NW
NE
SW
SE
model without isoprene
Isoprene emission [1013 atomC cm-2 s-1]
GOME isoprene emissions –
July 1996
[1012 atom C cm-2 s-1]
Consistency: GOME and in situ data
r2 = 0.77
Bias -12%
Global HCHO from GOME: July 1996
[1016 molec cm-2]
ATSR Firecounts – July 1996
Global HCHO from GOME: Oct 1996
[1016 molec cm-2]
Summary
 New methodology for HC emission from
space-based HCHO columns
 Isoprene is dominant HC for North
American summertime
GOME shows Ozarks isoprene volcano
GOME data consistent with in situ data
The future?
Acknowledgements
 Daniel Jacob, Arlene Fiore, Randall Martin
(Harvard University)
 Kelly Chance, Thomas Kurosu
(Harvard-Smithsonian Observatory)
http://www.people.fas.harvard.edu/~ppalmer