Using Satellite Observations to Understand Tropospheric Ozone Randall Martin

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

Challenge for the Next Decade: Improve Emission Inventories

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

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

Top-Down Information from the GOME Satellite Instrument Operational since 1995 Nadir-viewing solar backscatter instrument (237-794 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)

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)

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

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

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

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

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

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 -0.5 0 1016 molec cm-2 2.0 2.5 Agreement in general pattern, regional discrepancies point to need for improving GEOS-CHEM isoprene emissions Abbot et al., 2003

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

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

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

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

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

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

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

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

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

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

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

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 100-110 ppb 111-124 ppb 125+ ppb Canadian standard 82 ppb for 1-hour 65 ppb for 8 hour by 2010

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

Insignificant Trend (1980-1995) 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

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 . . .

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

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

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

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

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

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

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

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