satellite observations of atmospheric chemistry
DESCRIPTION
SATELLITE OBSERVATIONS OF ATMOSPHERIC CHEMISTRY. Daniel J. Jacob. OBSERVATION BY SOLAR OCCULTATION (UV to near-IR). “satellite sunrise”. Tangent point; retrieve vertical profile of concentrations. EARTH. Examples: SAGE, GOMOS. Recent extensions to lunar and stellar occultation. - PowerPoint PPT PresentationTRANSCRIPT
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)