SATELLITE OBSERVATIONS OF ATMOSPHERIC CHEMISTRYSATELLITE OBSERVATIONS OF ATMOSPHERIC CHEMISTRY

Daniel J. Jacob

OBSERVATION BY SOLAR OCCULTATION (UV to near-IR)OBSERVATION BY SOLAR OCCULTATION (UV to near-IR)

EARTH

“satellite sunrise”

Tangent point; retrieve vertical profile of concentrations

Recent extensions to lunar and stellar occultation

Examples:SAGE, GOMOS

OBSERVATION BY THERMAL EMISSION (IR, OBSERVATION BY THERMAL EMISSION (IR, wave)wave)

EARTH SURFACE

I(To)

Absorbinggas or aerosol

To

T1

I(T1)LIMB VIEW

NADIRVIEW

Examples: MLS, MOPITT, MIPAS, TES, HRDLS

OBSERVATION BY SOLAR BACKSCATTER (UV to near-IR)OBSERVATION BY SOLAR BACKSCATTER (UV to near-IR)

absorption

wavelength

Slant optical depth

EARTH SURFACE

Scattering by Earth surface and by atmosphere

Backscatteredintensity IB

“Slant column”

])(

)(ln[

1

2

B

BS I

I

SeffS

Examples: TOMS, GOME, SCIAMACHY, OMI

LIDAR MEASUREMENTSLIDAR MEASUREMENTS

EARTH SURFACE

backscatter by atmosphere

Laser pulse Examples: LITE, CALYPSO

MOST OBSERVATIONS OF ATMOSPHERIC COMPOSITION MOST OBSERVATIONS OF ATMOSPHERIC COMPOSITION FROM SPACE HAVE BEEN FOR THE STRATOSPHEREFROM SPACE HAVE BEEN FOR THE STRATOSPHERE

Tropopause

Stratopause

Observation of troposphereis far more difficult because of

• clouds• particles (dust)• water vapor continuum• strat ozone layer

Stratosphere

Troposphere

Ozonelayer

Mesosphere

2002 2002 2004 2004 2004 2004 2004

PRESENT AND FUTURE SATELLITE MEASUREMENTS PRESENT AND FUTURE SATELLITE MEASUREMENTS FOR TROPOSPHERIC CHEMISTRYFOR TROPOSPHERIC CHEMISTRY

ATMOSPHERIC CHEMISTRY MODELS AND SATELLITE ATMOSPHERIC CHEMISTRY MODELS AND SATELLITE OBSERVATIONS: THE ODD COUPLEOBSERVATIONS: THE ODD COUPLE

SATELLITE SPECTRA“L1 DATA”

ATMOSPHERIC CONCENTRATIONS

“L2 DATA”

RETRIEVALA PRIORI INFORMATIONvertical gradient,

concentration range,correlations…

SCIENTIFIC ANALYSIS“L4 DATA”

CLIMATOLOGICAL IN SITU OBSERVATIONS

ATMOSPHERIC CHEMISTRY MODELS

EVALUATIONASSIMILATION

INCREASEDKNOWELDGE

INCEST?

GEOS-CHEM global model of tropospheric chemistryGEOS-CHEM global model of tropospheric chemistry(www-as.harvard.edu/chemistry/trop/geos)(www-as.harvard.edu/chemistry/trop/geos)

• Driven by NASA GEOS assimilated meteorological data, 1988-2001

• 1ox1.25o- 4ox5o horizontal resolution, 20-48 layers in vertical

• Simulation of tropospheric ozone-NOx-hydrocarbon chemistry includes ~80 interacting species

THE GOME SATELLITE INSTRUMENTTHE GOME SATELLITE INSTRUMENT

• Nadir-viewing solar backscatter instrument (237-794 nm)

• Low-elevation polar sun-synchronous orbit, 10:30 a.m. observation time

• Field of view 320x40 km2, three cross-track scenes

• Complete global coverage in 3 days

USE GOME MEASUREMENTS OF NOUSE GOME MEASUREMENTS OF NO22 AND HCHO COLUMNS AND HCHO COLUMNS

TO MAP NOTO MAP NOxxAND VOC EMISSIONSAND VOC EMISSIONS

Emission

NOh (420 nm)

O3, RO2

NO2

HNO3

1 day

NITROGEN OXIDES (NOx) VOLATILE ORGANIC CARBON (VOC)

Emission

VOC

OHHCHOh (340 nm)

hoursCO

hours

BOUNDARYLAYER

~ 2 km

Tropospheric NO2 column ~ ENOx

Tropospheric HCHO column ~ EVOC

Deposition

GOME

AIR MASS FACTOR (AMF) CONVERTS AIR MASS FACTOR (AMF) CONVERTS SLANT COLUMN SLANT COLUMN SS TO VERTICAL COLUMN TO VERTICAL COLUMN

SAMF

“Geometric AMF” (AMFG) for non-scattering atmosphere:

EARTH SURFACE

cos

cos1GAMF

IN SCATTERING ATMOSPHERE, AMF DEPENDS ON IN SCATTERING ATMOSPHERE, AMF DEPENDS ON SHAPE OF VERTICAL PROFILE (FOR WHICH GOME SHAPE OF VERTICAL PROFILE (FOR WHICH GOME

PROVIDES NO INFORMATION)PROVIDES NO INFORMATION)

Observations

Model

SOS (southeast U.S., Jul 1995)

NARE (N. Atlantic, Sept 1997)

Palmer et al. [2001]

CALCULATE AMF FOR EVERY GOME SCENECALCULATE AMF FOR EVERY GOME SCENEUSING LOCAL SHAPE FACTORS FROM GEOS-CHEM USING LOCAL SHAPE FACTORS FROM GEOS-CHEM

0

)()( dzzSzwAMFAMF G

GeometricAMF

GOME efficiency= f (sun angle,albedo, cloud…)

RADIATIVETRANSFERMODEL

Vertical concentrationprofile shapefactor

ATMOSPHERIC CHEMISTRY MODEL (GEOS-CHEM)

Vertical column = Slant column

AMF

From GOME

From model

GOME sensitivity

ILLUSTRATIVE PROFILE OVER TENNESSEE

HCHO mixing ratioprofile (GEOS-CHEM)

what GOMEsees

AMFG = 2.08actual AMF = 0.71

SLANT COLUMNS OF NOSLANT COLUMNS OF NO22 FROM GOME FROM GOMEDominant stratospheric contribution (NODominant stratospheric contribution (NO22 produced from N 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)

Martin et al. [2002]

Remove stratospheric column and instrument artifacts using data over Pacific

SLANT COLUMNS OF TROPOSPHERIC NOSLANT COLUMNS OF TROPOSPHERIC NO22 FROM GOME FROM GOME

1996

Martin et al. [2002]

GOME RETRIEVAL OF TROPOSPHERIC NOGOME RETRIEVAL OF TROPOSPHERIC NO22

vs. GEOS-CHEM SIMULATION (July 1996)vs. GEOS-CHEM SIMULATION (July 1996)

Martin et al. [2002]

GEIA emissionsscaled to 1996

PROPAGATION OF ERRORS IN NOPROPAGATION OF ERRORS IN NO22 RETRIEVAL RETRIEVAL

(errors (errors in 10in 101515 molecules cm molecules cm-2-2))

GOME SPECTRUM (423-451 nm)

SLANT NO2 COLUMN

TROPOSPHERIC SLANT NO2 COLUMN

TROPOSPHERIC NO2 COLUMN

Fit spectrum

Remove stratospheric contribution, diffuser plate artifact

Use Central Pacific GOME data with:•HALOE to test strat zonal invariance•PEM-Tropics, GEOS-CHEM 3-D model to treat tropospheric residual

Apply AMF to convert slant column to vertical column

Use radiative transfer model with:• local vertical shape factors from GEOS-CHEM• local cloud information from CRAG

Martin et al. [2002]

CAN WE USE GOME TO ESTIMATE NOCAN WE USE GOME TO ESTIMATE NOx x EMISSIONS?EMISSIONS?

TEST IN U.S. WHERE GOOD TEST IN U.S. WHERE GOOD A PRIORI A PRIORI EXISTS EXISTSComparison of GOME retrieval (July 1996) to GEOS-CHEM model fields

using EPA emission inventory for NOx

GOME

GEOS-CHEM(EPA emissions)

BIAS = +3%

R = 0.79

Martin et al. [2002]

R = 0.78Bias = +18%

FORMALDEHYDE COLUMNS FROM GOME:FORMALDEHYDE COLUMNS FROM GOME:July 1996 meansJuly 1996 means

BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO IN U.S. IN SUMMER

Palmer et al. [2001]

GEIAisopreneemissions

R = 0.83Bias 14%

Precision:4x1015 cm-2

SLANT COLUMNS OF HCHO FROM GOMESLANT COLUMNS OF HCHO FROM GOMEHigh values over southeast U.S. are due to biogenic isoprene emissionHigh values over southeast U.S. are due to biogenic isoprene emission

Palmer et al. [2002]Note “isoprene volcano” over the Ozarks

DEPENDENCE OF GOME HCHO COLUMNSDEPENDENCE OF GOME HCHO COLUMNSOVER THE OZARKS ON SURFACE AIR TEMPERATUREOVER THE OZARKS ON SURFACE AIR TEMPERATURE

Temperature dependenceof isoprene emission (GEIA)

Palmer et al. [2002]

MODEL AS INTERMEDIARY FOR GOME VALIDATION:MODEL AS INTERMEDIARY FOR GOME VALIDATION:EVALUATE AGAINST IN SITU SURFACE OBSERVATIONS EVALUATE AGAINST IN SITU SURFACE OBSERVATIONS

Mean daytime HCHO surface observationsJun-Aug 1988-1998 Model (1996) vs. observations

Palmer et al. [2002]

USING GOME HCHO COLUMNS USING GOME HCHO COLUMNS TO MAP ISOPRENE EMISSIONSTO MAP ISOPRENE EMISSIONS

isoprene

HCHOhours

OH h, OH

hours

Displacement/smearing length scale 10-100 km

HCHO HCHOISOP

ISOP HCHO

kE

Yield

GEOS-CHEM RELATIONSHIP BETWEEN HCHO COLUMNS GEOS-CHEM RELATIONSHIP BETWEEN HCHO COLUMNS AND ISOPRENE EMISSIONS IN N AMERICAAND ISOPRENE EMISSIONS IN N AMERICA

Use relationship to map isoprene emissions from GOME observationsUse relationship to map isoprene emissions from GOME observations

Palmer et al. [2002]

GEOS-CHEMJuly 1996

NW NE

SESW

Isoprene emission [1013 atomC cm-2 s-1]

Mod

el H

CH

O c

olu

mn

[101

6 m

ole

c c

m-2

]

model without isoprene

MAPPING OF ISOPRENE MAPPING OF ISOPRENE EMISSIONS FOR JULY 1996 EMISSIONS FOR JULY 1996 BY SCALING OF GOME BY SCALING OF GOME FORMALDEHYDE COLUMNS FORMALDEHYDE COLUMNS [Palmer et al., 2002][Palmer et al., 2002]

GEIA (IGAC inventory)

BEIS2(official EPA inventory)

GOME

COMPARE TO…

NEXT STEP: NEXT STEP: GLOBAL MAPPING OF VOC EMISSIONS FROM SPACE! GLOBAL MAPPING OF VOC EMISSIONS FROM SPACE!

T. Kurosu (SAO) and P. Palmer (Harvard)

T. Kurosu (SAO) and P.I. Palmer (Harvard)