Inferring SO2 and NOx Emissions from Satellite Remote Sensing

Randall Martin

with contributions from

Akhila Padmanabhan, Gray O’Byrne, Sajeev Philip

Dalhousie U

Environment Canada Seminar

17 Jan 2011

Chulkyu Lee, Dalhouse U NIMR, Korea

Information about Anthropogenic SO2 Sources?Need Accurate SO2 Retrieval Algorithm

Lee et al., JGR, 2009

Local Air Mass Factor (AMF) Calculation

dt()

IoIB

EARTH SURFACE

Radiative Transfer Model

Scattering weight

B

e

I1w

ln)(

AMF)(

G

Atmospheric Chemistry Model

“a-priori” Shape factor

2

2

OO

( ) ( ) airS

S

S C

1

T

dSw )()(AMFvertical

slantAMF G

Calculate w() as function of:• solar and viewing zenith angle• surface albedo, pressure• cloud pressure, aerosol• OMI O3 column

INDIVIDUALOMI SCENES

SO2 mixing ratio CSO2()

() is temperature dependent cross-section

sig

ma

()

Local Air Mass Factor Improves Agreement with Aircraft Observations (INTEX-A and B)

Lee et al., JGR, 2009

Uniform AMF: slope = 1.6, r = 0.71 Local AMF: slope = 0.95, r = 0.92

Uniform AMF: slope = 1.3, r = 0.78 Local AMF: slope = 1.1, r = 0.89

SCIAMACHYOMI

Extend Air Mass Factor Calculation to Longer Time Period

SCIAMACHY OMI

Launch 2002 2004

Resolution (km) 30x60 >13x24

Repeat (days) 6 1-2

Equator Crossing Time 10:00 1:45

Provide daily local SO2 AMFs and scattering weights so any model can be used in the analysis

NO2 & SO2 Retrievals Affected by Errors in Surface Reflectance and Clouds

Winter OMI NO2 over Calgary & Edmonton

6OMI Reported Cloud Fraction

≥ 5cm of snow

0 > snow < 5cm

no snow

Mea

n T

rop

. N

O2

(mo

lec/

cm2 )

O’Byrne et al., JGR, 2010

Expected Retrieval Bias OMI NO2 for Snow-Covered ScenesDue to Errors in Accounting for Transient Snow & Ice

7

2

original correctedRelative NO Bias

corrected

With CloudFractionThreshold (f < 0.3)

-0.5 0 1.0

O’Byrne et al., JGR, 2010

Trend in Summer Tropospheric NO2 Column over 2003-2009 from SCIAMACHY

Akhila Padmanabhan & Chris Sioris

Bottom-Up Emission Inventories Take Years to Compile

Evaluate Hindcast Inventory Versus Bottom-upHindcast for 2003 Based on Bottom-up for 2006 and Monthly

NO2 for 2003-2006

Lamsal et al., GRL, 2011

HindcastBottom-up

Application of Satellite Observations for Timely Updates to NOx Emission Inventories

Use Model to Calculate Local Sensitivity of Changes in Trace Gas Column to Changes in Emissions

Forecast Inventory for 2009 Based on Bottom-up for 2006 and Monthly SCIAMACHY NO2 for 2006-2009

Temporary Dataset Until Bottom-Up Inventory Available

Lamsal et al., GRL, 2011

9% increase in global emissions

19% increase in Asian emissions

6% decrease in North American emissions

Top-Down (Mass Balance) Constraints on Emissions

SCIAMACHY Tropospheric NO2 (1015 molec cm-2) NOx emissions (1011 atoms N cm-2 s-1)

Lee et al., 2011

2004-2005

Inverse Modeling

SOx emissions (1011 atoms N cm-2 s-1)SCIAMACHY SO2 (1016 molec cm-2)

200652.4 Tg S yr-1

Martin et al., 2006

Accuracy of Mass Balance Approach for SO2 and NOx Emissions?

Mass Balance Approach•exploits short lifetimes

•Easily implemented for many forward models

•Infer emissions E from local trace gas column Ω

modeltop-down sat

model

EE

Box A Box B

Accuracy of Mass Balance Approach for SO2 and NOx Emissions?

Test with Adjoint Approach

Mass Balance Approach•exploits short lifetimes

•Easily implemented for many forward models

•Infer emissions E from trace gas column Ω

Adjoint Approach•Explicitly accounts for spatial smearing

•Minimize Cost Function J~[model(E)-obs(Ω)]2

•Use adjoint model to calculate sensitivities λto produce improve estimate of E

modeltop-down sat

model

EE

EJ