Terrestrial emissions of isoprene

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Terrestrial emissions of isoprene
Paul Palmer Division of Engineering and Applied
Sciences, Harvard University
http//www.people.fas.harvard.edu/ppalmer
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Tropospheric O3 is an important climate forcing
agent
Level of Scientific Understanding
Natural VOC emissions (50 isoprene) CH4
emissions.
IPCC, 2001
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Isoprene emissions July 1996
Isoprene oxidation products (e.g. HCHO) provide
constraints on estimated emissions
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GOME isoprene emissions (July 1996) agree with
surface measurements
Modeled HCHO ppb
Observed HCHO ppb
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Modeling the terrestrial biosphere
PAR direct and diffuse (GMAO)
Temperature Instantaneous (G95) 10-day avg
(Petron 01)
Fixed base emission factors (Guenther 2004)
Canopy model (Guenther 1995)
Altitude
Emission
MODIS/AVHRR LAI
Emissions
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Global 3-D Modeling Overview

• Driven by NASA GMAO met data
• 2x2.5o resolution/30 vertical levels
• O3-NOx-VOC-aerosol chemistry

Monthly mean LAI (AVHRR/MODIS)
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Isoprene
Monoterpenes
MBO
VOC emissions during 2001 growing season
1012 atom C cm-2 s-1
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HCHO production from biogenics using the MCM
Y become closer at t progresses further
isoprene
0.5
0.33
Cumulative HCHO yield per C
GEOS-CHEM
HOURS
Use this analysis to parameterise source of HCHO
from monoterpenes
Mike Pilling and Jenny Stanton, Leeds University
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Global Ozone Monitoring Experiment

• Nadir-viewing SBUV instrument
• Pixel 320 x 40 km2
• 10.30 am cross-equator time (globe in 3 days)
• O3, NO2, BrO, OClO, SO2, HCHO, H2O, cloud

• HCHO slant columns fitted 337-356nm
• Fitting uncertainty lt continental signals

Isoprene
Biomass Burning
HCHO JULY 1997
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GROWING SEASON 2001
HCHO column 1016 molec cm-2
HCHO column signal from monoterpenes is
comparable to GOME column uncertainty
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HCHO data over the Ozarks
GOME
c/o Y-N. Lee, Brookhaven National Lab.
1016 molec cm-2
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Relating HCHO Columns to VOC Emissions
Master Chemical Mechanism
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EVALUATE GOME DATA USING LONG-TERM ISOPRENE FLUX
DATA PROPHET RESEARCH SITE (MI)
Maple, beech, birch, basswood, mixed aspen, bog
conifers (lower, wet areas), and pine and red oak
(drier upland regions).  Average height near 20
m.  Overstory age of the hardwood forest is
approximately 75 years.
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Long term in situ isoprene flux measurements at
PROPHET site during 2001
Isoprene flux 1012 molec cm-2 s-1
Measured (WSU) MEGAN GOME
HCHO column 1016 molec cm-2
/- uncertainty
Y2K1 Day
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May
July
June
September
August
1996
1997
1998
1999
2000
2001
HCHO column 1016 molec cm-2
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Interannual variability of the seasonal cycle
GOME HCHO Column 1016 molec cm-2
Southeast US 32-38N 265-280W
Days 2K1
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In situ observations over Atlanta GA provide some
verification of large interannual variability
Mean values associated with individual values gt
30 ppbC
Lance McCluney, EPA
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What is driving this variability?
2nd-order polynomial fit to HCHO columns
Curve based on greenhouse data (Guenther)
r0.9
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Closing Remarks

• GOME HCHO data provide constraints on natural VOC
  emissions
• Data consistent with seasonal and interannual
  variability observed with in situ measurements
• Improved understanding and quantification of air
  quality and climate
• Just the beginningneed to relate
  model-observation discrepancy to a better
  understanding of the underlying processes