Using Satellite Data to Infer Surface Emissions and Boundary Layer Concentrations of NOx (and SO2)

Randall Martin

With contributions from:With contributions from:Xiong Liu, Chris Sioris, Kelly Chance (Harvard-Smithsonian Center for Astrophysics)Xiong Liu, Chris Sioris, Kelly Chance (Harvard-Smithsonian Center for Astrophysics)

Rob Pinder, Robin Dennis (EPA/NOAA)Rob Pinder, Robin Dennis (EPA/NOAA)

Satellite Instruments With the Capability of Remote Satellite Instruments With the Capability of Remote Sensing of Tropospheric NOSensing of Tropospheric NO22 and SO and SO2 2 ColumnsColumns

•Nadir-viewing solar backscatter instruments including visible (NO2) and ultraviolet (SO2) wavelengths

GOME/ERS-2 1995-2002•Spatial resolution 320x40 km2

•Global coverage in 3 days

•SCIAMACHY/Envisat 2002-presentSpatial resolution 60x30 km2

Global coverage in 6 days

•OMI/Aura 2004-presentSpatial resolution 24x13 km2

Daily global coverage

Spectral Fit of NOSpectral Fit of NO22

Scattering by Earth surface and by atmosphere

Backscatteredintensity IB

Solar Io

Distinct NO2 Spectrum

seIAIB )()()( 0

Nonlinear least-squares fitting

Ozone

NO2

O2-O2

Albedo A

Martin et al., 2002, 2006

Total NOTotal NO22 Slant Columns Observed from SCIAMACHY Slant Columns Observed from SCIAMACHY Dominant stratospheric background (where NODominant stratospheric background (where NO22 is produced from N is produced from N22O oxidation)O oxidation)

Also see tropospheric hot spots (fossil fuel and biomass burning)Also see tropospheric hot spots (fossil fuel and biomass burning)

May-October 2004

Retrieval Uncertainty

Spectral fit 5-10x1014 molec cm-2

Stratospheric removal 2-10x1014 molec cm-2

Perform an Air Mass Factor (AMF) Calculation to Account for Perform an Air Mass Factor (AMF) Calculation to Account for Viewing Geometry and ScatteringViewing Geometry and Scattering

RcRo

IB,o IB,c

Pc

Rs

•GOMECAT (Kurosu) & FRESCO Clouds Fields [Koelemeijer et al., 2002]

•Surface Reflectivity [Koelemeijer et al., 2003]

•LIDORT Radiative Transfer Model [Spurr et al., 2002]

•GEOS-CHEM NO2 & aerosol profiles

d

Io

Palmer et al., 2001; Martin et al., 2002, 2003

Cloud Radiance Fraction IB,c / (IB,o + IB,c)

AMF Uncertainty 40%

Cloud-filtered Tropospheric NOCloud-filtered Tropospheric NO22 Columns Retrieved from Columns Retrieved from

SCIAMACHYSCIAMACHY

May 2004 – Apr 2005

Martin et al., 2006

Mean Uncertainty ±(5x1014 + 30%)

Tropospheric NOTropospheric NO22 Columns More Sensitive to Lower Columns More Sensitive to Lower

Tropospheric NOxTropospheric NOx

NO NO2

NOx lifetime < day

Nitrogen Oxides (NOx)

BoundaryLayer

NO/NO2

with altitude

hv

NO NO2

O3, RO2

hv

HNO3

NOx lifetime ~ week

Ozone (O3)

Upper Troposphere

Ozone (O3)

HNO3

O3, RO2

ICARTT Campaign Over and Downwind of Eastern North America in ICARTT Campaign Over and Downwind of Eastern North America in Summer 2004 Summer 2004

Aircraft Flight Tracks and Aircraft Flight Tracks and Validation LocationsValidation Locations Overlaid on SCIAMACHY Overlaid on SCIAMACHY Tropospheric NOTropospheric NO2 2 ColumnsColumns

NASA DC-8 NOAA WP-3D

Martin et al., 2006

Significant Agreement Between Coincident Cloud-Filtered Significant Agreement Between Coincident Cloud-Filtered SCIAMACHY and In-Situ MeasurementsSCIAMACHY and In-Situ Measurements

r = 0.77

slope = 0.82

1:1 line

Ryerson (WP-3D)

Cohen (DC-8)

Cloud-radiance fraction < 0.5

In-situ measurements below 1 km & above 3 km

Assume constant mixing ratio below lowest measurement

Add upper tropospheric profile from mean obs

Horizontal bars show 17th & 83rd percentilesMartin et al., 2006

Errorweighting

Conduct a Chemical Inversion For NOx EmissionsConduct a Chemical Inversion For NOx Emissions

A posteriori emissionsxTop-Down Emissions

1015 molec N cm-2

A Priori NOx Emissions (xa)SCIAMACHY NO2 Columns (y)

1011 molec N cm-2 s-1

GEOS-CHEM model F(x)

( ) ( T TJ -1 -1y a a ax y F(x)) S (y - F(x)) + (x - x ) S (x - x )min cost function

Sy

Sa

19982004-2005

Significant Agreement Between A Priori and A PosterioriSignificant Agreement Between A Priori and A PosterioriLargest Discrepancy in East AsiaLargest Discrepancy in East Asia

r=0.91

Martin et al., 2006

0

2

4

6

8

10

12

East Asia NorthAmerica

Europe Africa SE Asia& India

SouthAmerica

Australia

NO

x E

mis

sio

ns

(Tg

N/y

r)

A Posteriori NOx Emissions from East Asia Exceed A Posteriori NOx Emissions from East Asia Exceed Those from Either North America or EuropeThose from Either North America or Europe

A posteriori (46 Tg N/yr)

A priori (38 Tg N/yr)

CMAQ SCIAMACHY

On-going efforts:• Model Evaluation (2004)• Test and Improve NOx Emission Inventories

molec/cm2

Evaluation of Modeled Spatial DistributionsEvaluation of Modeled Spatial DistributionsNONO22 Columns: Summer 2004 Columns: Summer 2004

Rob Pinder, Robin Dennis

Similar discrepancies at surface

Comparable spatial distributionsSCIAMACHY higher in rural areas higher regional background missing source (lightning) or NOxNOy too rapid

CMAQ higher downwind of urban areas (e.g., Atlanta, St. Louis), Point sourcesair mass factor from GEOS-CHEM NOx lifetime difference due to resolution

Evaluation of NOEvaluation of NO22 Spatial Distributions (contd.) Spatial Distributions (contd.)

Rob Pinder, Robin Dennis

CMAQ EvaluationCMAQ -SCIAMACHY

Can Satellite Measurements of Tropospheric NOCan Satellite Measurements of Tropospheric NO22

Columns Provide a Proxy for Surface NOColumns Provide a Proxy for Surface NO22 In Regions In Regions

Without In Situ Measurements?Without In Situ Measurements?

Highest NO2 maximum quarterly mean by county, 2001

Relationship Between Surface NORelationship Between Surface NO22 and GOME NO and GOME NO22

Columns Northern ItalyColumns Northern Italy

Ordonez et al., JGR, 2006

Fall/Winter Spring/Summer

In Situ Measurements Corrected for NOy Contamination

Relationship Between Simulated (GEOS-Chem) Relationship Between Simulated (GEOS-Chem) and Measured NOand Measured NO22 Profiles over Land Profiles over Land

Martin et al., 2004

Texas AQSTexas AQS

ICARTTICARTT

Martin et al., 2006

In Situ

GEOS-Chem (standard) (lightning x 4)

In Situ

GEOS-Chem

CMAQ SCIAMACHY

molec/cm2

Infer Surface NOInfer Surface NO22 from Tropospheric NOfrom Tropospheric NO22 Column Using Column Using

Model Vertical ProfileModel Vertical Profile

(Courtesy: R. Martin)

Rob Pinder, Robin Dennis

ppm

Satellite Retrieval of SOSatellite Retrieval of SO22

• Challenging! (Ozone Interference, Rayleigh Scattering <330 nm)

• TOMS: detect volcanic eruptions (detection limit: 4-6 DU) [Krueger, 1983; Krueger et al., 1995]

• GOME: detect both volcanic & anthropogenic SO2 [Eisinger & Burrows, 1998; Khokhar et al., 2005] using the DOAS technique (detection limit: 0.5-1 DU)

Global Distribution of SOGlobal Distribution of SO2 2 Columns Retrieved from GOMEColumns Retrieved from GOME

Missing Source from Nyamuragira Volcano in October 1998Missing Source from Nyamuragira Volcano in October 1998Retrieval Issues in July?Retrieval Issues in July?

GOMEGEOS-Chem

Xiong Liu

Do

bso

n U

nits

Oct98 Oct98

Jul97 Jul97

ConclusionsConclusions

• Top-down information from satellites can be applied to improve NOx emission inventories

• OMI will provide this capability at higher resolution

• Additional model development necessary for application at local scale

• Encouraging prospect of inferring surface NO2 from satellite/model