1. Using Satellite Observations to Understand Tropospheric Ozone
Randall Martin

2. ? ? ? Tropospheric Ozone Formaldehyde (HCHO) Lightninghv
hv,H2O
Nitrogen oxides (NOx)
CO, Volatile Organic Compounds (VOCs) ?
Ozone (O3)
Hydroxyl (OH)
Fires
Biosphere
Human
activity

3. Challenge for the Next Decade: Improve Emission Inventories

4. Seasonal Variation in Biomass Burning Determined from Space-based ATSR Firecounts
Annual BB Emission Inventory (Logan & Yevich)
Observed Daily Satellite FireCounts
molecules CO cm-2 month-1
Duncan, Martin, et al., JGR, 2003

5. How Do We Evaluate and Improve A Priori Bottom-up Inventories?
Surface NOX
Isoprene during July
North American Isoprene Emissions (3-15 Tg C yr-1)
Global NOx Emissions (Tg N yr-1)
Fossil Fuel 24 (20-33) Biomass Burning 6 (3-13) Soils 5 (4-21)
GEIA

6. Top-Down Information from the GOME Satellite Instrument
Operational since 1995
Nadir-viewing solar backscatter instrument ( nm)
Low-elevation polar sun-synchronous orbit, 10:30 a.m. observation time
Spatial resolution 320x40 km2, three cross-track scenes
Complete global coverage in 3 days
Predecessor to SCIAMACHY (30x60 km2) and OMI (13x24 km2)

7. Use GOME Measurements to Retrieve Tropospheric NO2 and HCHO Columns to Map NOx and VOC Emissions
Tropospheric NO2 column ~ ENOx
Tropospheric HCHO column ~ EVOC
BOUNDARY
LAYER
NO2
NO/NO2  
W ALTITUDE NO
HCHO CO OH
hours
hours
VOC
lifetime hours
HNO3
Emission
Emission
NITROGEN OXIDES (NOx)
VOLATILE ORGANIC COMPOUND (VOC)

8. Perform a Spectral Fit of Solar Backscatter Observations
absorption
Solar Io
Backscattered
intensity IB l1 l2
wavelength
Slant optical depth
“Slant column”
Scattering by
Earth surface
and by atmosphere
EARTH SURFACE

9. Perform a Radiative Transfer Calculation to Account for Viewing Geometry and Scattering Cloud Screening: Remove Scenes with IB,c > IB,o
IB,o
IB,c Io q
LIDORT Radiative Transfer Model [Spurr et al., 2002]
GOME Clouds Fields [Kurosu et al., 1999]
GOME Surface Reflectivity [Koelemeijer et al., 2001] Rc Ro Pc t dt Rs

10. HCHO Columns Retrieved from GOME (July 1996)
2.5x1016
molecules
cm-2 2
1.5 1
detection
limit
0.5
South
Atlantic
Anomaly
(disregard)
-0.5
High HCHO regions reflect VOC emissions from fires, biosphere, human activity

11. Tropospheric NO2 Columns Retrieved from GOME (July 1996)
6x1015
molecules
cm-2 4 2
detection
limit
Martin et al., 2002b

12. Compare with Bottom-up Inventories Using GEOS-CHEM Chemical Transport Model
Assimilated Meteorology (GEOS)
2ox2.5o horizontal resolution, 26 layers in vertical
O3-NOx-VOC chemistry
Radiative and chemical effects of aerosols
Anthropogenic and natural emissions
Cross-tropopause transport
Deposition
Seasonal and Interannual Biomass Burning Based on ATSR Firecounts
Bey et al., JGR, 1999
Martin et al., JGR, 2002a
Martin et al., JGR, 2003a
Calculated Mean Surface Ozone for August 1997

13. GEOS-CHEM isoprene emissions
GOME HCHO Columns Show Seasonal VOC Emissions
GOME GEOS-CHEM (GEIA) GOME GEOS-CHEM (GEIA)
MAR
JUL
APR
AUG
MAY
SEP
JUN
OCT
molec cm
Agreement in general pattern, regional discrepancies point to need for improving
GEOS-CHEM isoprene emissions
Abbot et al., 2003

14. GOME HCHO Columns Dominated by Biogenic Isoprene Even Over Eastern Texas
Martin et al., JGR, submitted

15. GEOS-CHEM Tropospheric NO2
GOME Tropospheric NO2
GEOS-CHEM Tropospheric NO2
r=0.75 bias 5%
Martin et al., 2003b
1015 molecules cm-2

16. STRATEGY: Optimize Surface Inventories by Combining A Priori Bottom-up and GOME Top-down Information
Top-down emissions
A priori emissions
A posteriori emissions
A priori errors
Top-down errors
Martin et al., 2003b
GOME
GEOS-CHEM

17. Optimized Surface NOX Emissions
36.4 Tg N yr-1
37.7 Tg N yr-1
Martin et al., 2003b

18. A Posteriori Minus A Priori Emissions
Martin et al., 2003b

19. GOME Tropospheric NO2 Generally Consistent With In Situ Measurements from Aircraft Over Houston
geometric mean ratio = 1.08
In Situ NO2 Measurements by Tom Ryerson
Martin et al., JGR, submitted

20. A Posteriori Minus A Priori Emissions
Martin et al., 2003b

21. Biogenic soil emissions of NO
“Hole-in-the-pipe model”
Davidson et al. 2000
Soil emissions of NO:
 with temperature;  with precipitation (up to a point)
“pulsing”: when it rains after dry period
 after burning of vegetation
Canopy recapture.
In situ measurements show NOx emissions
2-4 times larger than included in a priori
NO and N2O produced in soils by nitrifying and denitrifying bacteria.
NO/N2O flux = function of nitrogen cycling + soil moisture controls size of holes (transport of O2/NO in soils)
Burning enhances biogenic soil emissions of NO: increase in ammonium (burn ash)  increase in nitrogen available
Pulsing: light rain after extended dry period: release of built-up inorganic nitrogen trapped in dry soil + reactivation of water stresses bacteria which
Metabolize the excess nitrogen
Large uncertainties: soil emissions could contribute to 40% of global NOx budget

22. NOx Emissions From Sahel During Wet Season
Jaeglé, Martin, et al., submitted

23. GOME Observes Pulsing of Soil NOx Emissions in Sahel
Jaeglé, Martin, et al., submitted

24. Soils Contribute 40% of Surface NOx Emissions from Africa
Jaeglé, Martin, et al., submitted

25. 0-60 ppb 61-79 ppb 80-99 ppb 100-110 ppb 111-124 ppb 125+ ppb
Surface Ozone Remains a Major Issue in North America Peak Surface Ozone Concentration For a “Typical” Episode
1-hour Average Peak Concentration
          
0-60 ppb
61-79 ppb
80-99 ppb
ppb
ppb
125+ ppb
Canadian standard 82 ppb for 1-hour
65 ppb for 8 hour by 2010

26. Surface ozone concentrations are sensitive to the ratio of NOx emissions to VOC emissions
(ppbv)
NOx Saturated
NO2 + OH
NOx Sensitive
HO2 + HO2
Sillman and He, 2002

27. Insignificant Trend ( ) in Observed Summer Afternoon Ozone Over Most of the United States despite 12% decrease in VOC emissions (no change in NOx emissions) Decreasing trend in major metropolitan centers
Fiore et al., JGR, 1998

28. Ozone Control Strategies Require Independent Information on Effectiveness of Reducing NOx or VOCs
Sillman introduced the concept of NOx-VOC indicators, i.e. HCHO/NOy (NOy = total reactive nitrogen)
NOx-saturated
NOx-sensitive
HCHO strongly correlated with HOx source & VOC oxidation
Predicted reduction in peak (afternoon) ozone for a 35% decrease in NOx and VOC emissions
VOC
Sillman, JGR, 1995
Would like to observe this transition from space
Can observe tropospheric NO2 and HCHO columns . . .

29. Diagnose Indicators with GEOS-CHEM Model
Conduct Three Simulations
Base Case
Reduce Anthropogenic NOx Emissions by 50%
Reduce Anthropogenic VOC Emissions by 50%
Fiore et al., JGR, 2002
Calculated Mean Surface Ozone for August 1997

30. Tropospheric HCHO/NO2 Column Ratio Is an Indicator of the Sensitivity of Afternoon Surface Ozone to NOx and VOC Emissions in a Well-mixed Environment GEOS-CHEM Model Calculation For Polluted Regions, Mar-Nov
NOx Saturated
NOx Sensitive
Martin et al., 2004

31. GOME Observations Show NOx-Sensitive Conditions Over Most Polluted Regions During August Major Industrial Areas are Clear Exceptions
White areas indicate clouds or data below the GOME detection limit
August
Martin et al., 2004

32. Seasonal Evolution from NOx-Sensitive to NOx-Saturated Conditions in Fall
Martin et al., 2004

33. GOME Observations Provide Confidence in a Recent Model Prediction NOx-Sensitive in the South and NOx-Saturated in the North in Fall
Seasonal Maximum in Surface Ozone in Urban China Occurs in Fall (More High-Pressure Systems)
GOME
Model
Luo et al., JGR, 2000

34. Biomass Burning Emissions are Clearly NOx-Sensitive, In Contrast with NOx-Saturated Conditions Over the Industrial Highveld
Also observe plume evolution
August

35. SCIAMACHY Provides Much Finer Spatial Resolution (30 km x 60 km)
OMI (13 km x 24 km) Will Be Launched in June
AUG 2002

36. Daniel Jacob Dorian Abbot Paul Palmer
Aaron Van Donkelaar
Arlene Fiore
David Parrish
Tom Ryerson
Lyatt Jaeglé
Daniel Jacob Dorian Abbot Paul Palmer
Kelly Chance Thomas Kurosu Chris Sioris