observation of atmospheric composition from space daniel j. jacob, harvard university
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OBSERVATION OF ATMOSPHERIC COMPOSITION FROM SPACEOBSERVATION OF ATMOSPHERIC COMPOSITION FROM SPACE
Daniel J. Jacob, Harvard University
NASA NASA Earth & Sun Earth & Sun SpacecraftSpacecraft
STRATOSPHERIC OZONE HAS BEEN MEASURED STRATOSPHERIC OZONE HAS BEEN MEASURED FROM SPACE SINCE 1979FROM SPACE SINCE 1979
Method: UV solar backscatter
Scattering by Earth surface and atmosphere
Ozone layer
Ozoneabsorptionspectrum
ATMOSPHERIC COMPOSITION RESEARCH IS NOW MORE ATMOSPHERIC COMPOSITION RESEARCH IS NOW MORE DIRECTED TOWARD THE TROPOSPHEREDIRECTED TOWARD THE TROPOSPHERE
Tropopause
Stratopause
Stratosphere
Troposphere
Ozonelayer
Mesosphere
…but tropospheric composition measurements from space are difficult:optical interferences from water vapor, clouds, aerosols, surface, ozone layer
Air quality, climate change, ecosystem issues
WHY OBSERVE TROPOSPHERIC COMPOSITION FROM SPACE?WHY OBSERVE TROPOSPHERIC COMPOSITION FROM SPACE?
Monitoring and forecastingof air quality: ozone, aerosols
Long-range transport of pollution
Monitoring of sources:pollution and greenhousegases
• solar backscatter• thermal emission• solar occultation• lidar
FOUR OBSERVATIONMETHODS:
Global/continuous measurement capability important for range of issues:
Radiative forcing
SOLAR BACKSCATTER MEASUREMENTS (UV to near-IR)SOLAR BACKSCATTER MEASUREMENTS (UV to near-IR)
absorption
wavelength
Scattering by Earth surface and by atmosphere
Examples: TOMS, GOME, SCIAMACHY, MODIS, MISR, OMI, OCO
Pros:• sensitivity to lower troposphere• small field of view (nadir) Cons:
• Daytime only• Column only• Interference from stratosphere
concentration
Retrieved column in scattering atmospheredepends on vertical profile; need chemical transportand radiative transfer models
z
THERMAL EMISSION MEASUREMENTS (IR, THERMAL EMISSION MEASUREMENTS (IR, wave)wave)
EARTH SURFACE
I(To)
Absorbing gas
To
T1
I(T1)LIMB VIEW
NADIRVIEW
Examples: MLS, IMG, MOPITT, MIPAS, TES, HIRDLS, IASI
Pros:• versatility (many species)• small field of view (nadir)• vertical profiling
Cons:• low S/N in lower troposphere• water vapor interferences
OCCULTATION MEASUREMENTS (UV to near-IR)OCCULTATION MEASUREMENTS (UV to near-IR)
EARTH
“satellite sunrise”
Tangent point; retrieve vertical profile of concentrations
Examples: SAGE, POAM, GOMOS
Pros:• large signal/noise• vertical profiling Cons:
• sparse data, limited coverage• upper troposphere only• low horizontal resolution
LIDAR MEASUREMENTS (UV to near-IR)LIDAR MEASUREMENTS (UV to near-IR)
EARTH SURFACE
backscatter by atmosphere
Laser pulse
Examples: LITE, GLAS, CALIPSO
Intensity of return vs. time lag measures vertical profile
Pros: • High vertical resolution
Cons:• Aerosols only (so far)• Limited coverage
ALL ATMOSPHERIC COMPOSITION DATA SO FAR HAVE BEEN ALL ATMOSPHERIC COMPOSITION DATA SO FAR HAVE BEEN FROM LOW-ELEVATION, SUN-SYNCHRONOUS POLAR ORBITERSFROM LOW-ELEVATION, SUN-SYNCHRONOUS POLAR ORBITERS
• Altitude ~ 1,000 km
• Observation at same time of day everywhere
• Period ~ 90 min.
• Coverage is global but sparse
TROPOSPHERIC COMPOSITION FROM SPACE:TROPOSPHERIC COMPOSITION FROM SPACE:platforms, instruments, speciesplatforms, instruments, species
Sensor TOMS GOME MOPITT MISR MODIS AIRS SCIA-MACHY
TES MLS OMI OCO
Platform (launch)
multi
(1979-)
ERS-2 (1995)
Terra Aqua
(1999) ( 2002)
Envisat (2002)
Aura
(2004) 2008
ozone X (tro-pics)
X X X X
CO X X X X
CO2 X
CH4 X
NO2 X X X
HNO3 X
HCHO X X
BrO X X
aerosol X X
NASA AURA SATELLITE (launched July 2004)NASA AURA SATELLITE (launched July 2004)
AuraAuraMLS
TES nadirTES nadirOMIOMI
HIRDLS Direction of motion
TES limbTES limb
Polar orbit; four passive instruments observing same air mass within 14 minutes
•OMI: UV/Vis solar backscatter• NO2, HCHO. ozone, BrO columns
• TES: high spectral resolution thermal IR emission• nadir ozone, CO• limb ozone, CO, HNO3
•MLS: microwave emission• limb ozone, CO (upper troposphere)
• HIRDLS: high vertical resolution thermal IR emission• ozone in upper troposphere/lower stratosphere
Tropospheric measurement capabilities:
OBSERVING TROPOSPHERIC OZONE AND ITS SOURCES FROM SPACE
Nitrogen oxide radicals; NOx = NO + NO2
Sources: combustion, soils, lightningMethaneSources: wetlands, livestock, natural gasNonmethane VOCs (volatile organic compounds)Sources: vegetation, combustionCO (carbon monoxide)Sources: combustion, VOC oxidation
Troposphericozone
precursors
CONSTRAINING NOCONSTRAINING NOxx AND REACTIVE VOC EMISSIONS AND REACTIVE VOC EMISSIONS
USING SOLAR BACKSCATTER MEASUREMENTSUSING SOLAR BACKSCATTER MEASUREMENTSOF TROPOSPHERIC NOOF TROPOSPHERIC NO22 AND FORMALDEHYDE (HCHO) AND FORMALDEHYDE (HCHO)
Emission
NOh (420 nm)
O3, RO2
NO2
HNO3
1 day
NITROGEN OXIDES (NOx) VOLATILE ORGANIC COMPOUNDS (VOC)
Emission
VOC
OHHCHOh (340 nm)
hoursCO
hours
BOUNDARYLAYER
~ 2 km
Tropospheric NO2 column ~ ENOx
Tropospheric HCHO column ~ EVOC
Deposition
GOME: 320x40 km2
SCIAMACHY: 60x30 km2 OMI: 24x13 km2
K. Folkert Boersma (Harvard)
TROPOSPHERIC NOTROPOSPHERIC NO22 FROM OMI: CONSTRAINT ON NO FROM OMI: CONSTRAINT ON NOxx SOURCES SOURCES
October 2004
K. Folkert Boersma (Harvard)
TROPOSPHERIC NOTROPOSPHERIC NO22 FROM OMI: ZOOM ON U.S. AND MEXICO FROM OMI: ZOOM ON U.S. AND MEXICO
MILAGRO campaign, March 2006
1996-2005 TREND IN NO1996-2005 TREND IN NOxx EMISSIONS SEEN FROM SPACE EMISSIONS SEEN FROM SPACE Van der A et al., in prep.
FORMALDEHYDE COLUMNS MEASURED BY GOME FORMALDEHYDE COLUMNS MEASURED BY GOME (JULY 1996) (JULY 1996)
High HCHO regions reflect VOC emissions from fires, biosphere, human activity
-0.5
0
0.5
1
1.5
2
2.5x1016
moleculescm-2
SouthAtlanticAnomaly(disregard)
detectionlimit
FORMALDEHYDE COLUMNS FROM OMI OVER U.S. (July 2005):FORMALDEHYDE COLUMNS FROM OMI OVER U.S. (July 2005): biogenic isoprene is the principal reactive VOC biogenic isoprene is the principal reactive VOC
OMIGEOS-Chem chemical transport model
with best prior estimates of VOC emissions
Dylan B. Millet (Harvard) and Thomas Kurosu (Harvard-SAO)
SEASONALVARIATION OF GOME FORMALDEHYDE COLUMNS SEASONALVARIATION OF GOME FORMALDEHYDE COLUMNS reflects seasonal variation of biogenic isoprene emissionsreflects seasonal variation of biogenic isoprene emissions
SEP
AUG
JUL
OCT
MAR
JUN
MAY
APR
GOME GEOS-Chem (GEIA) GOME GEOS-Chem (GEIA)
Abbot et al. [2003]
GOME JJA 1997 tropospheric columns (Dobson Units)
TROPOSPHERIC OZONE OBSERVED FROM SPACETROPOSPHERIC OZONE OBSERVED FROM SPACE
Is there a summer maximum over the Middle East?
GEOS-Chem model maximum [Li et al., GRL 2001]:
Is it real?
IR emission measurement from TES UV backscatter measurement from GOME
Liu et al., 2006
TES ozone and CO observations in July 2005 at 618 hPaTES ozone and CO observations in July 2005 at 618 hPa
TES observations of ozone-CO correlations can test CTM simulations of ozone continental outflow
North America
Asia
Zhang et al., 2006
USING ADJOINTS OF CHEMICAL TRANSPORT MODELS TO USING ADJOINTS OF CHEMICAL TRANSPORT MODELS TO INVERT FOR EMISSIONS WITH HIGH RESOLUTIONINVERT FOR EMISSIONS WITH HIGH RESOLUTION
MOPITT daily CO columns(Mar-Apr 2001) Correction to model
sources of CO
A priori emissions fromStreets et al. [2003] andHeald et al. [2003]
Monika Kopacz, Harvard
Inverse ofatmospheric
model
(sensitivity)
OBSERVING COOBSERVING CO22 FROM SPACE: FROM SPACE:
Orbiting Carbon Observatory (OCO) to be launched in 2008Orbiting Carbon Observatory (OCO) to be launched in 2008
Polar-orbiting solar backscatter instrument, measures CO2 absorption at 1.61 and 2.06 m, O2 absorption (surface pressure) at 0.76 m: global mapping of CO2 column mixing ratio with 0.3% precision
Averaging kernel
Pre
ss
ure
(h
Pa
)
OCO will provide powerful constraintson regional carbon fluxes
UV-IR sensors would provide continuous high-resolution mapping (~1 km)
on continental scale: boon for air quality monitoring and forecasting
LOOKING TOWARD THE FUTURE: LOOKING TOWARD THE FUTURE: GEOSTATIONARY ORBITGEOSTATIONARY ORBIT
LAGRANGE POINTS MISSION CONCEPTSLAGRANGE POINTS MISSION CONCEPTS
L1: view full disk of sunlit Earth• nadir obs as in geostationary• continuous obs from sunrise to sunst
L2: nighttime Earthcontinuous solaroccultation measurements
PROPOSED L-1 MISSION TO NASAPROPOSED L-1 MISSION TO NASA(Janus)(Janus)
L-1 point : 1.5 million km from Earth along Earth- Sun line
NH and SH summer views from L-1:global continuous daytime coverage
• Continuous global observation of Earth sunlit disk with 5 km nadir resolution
• UV-IR spectrometers for observation of ozone, NO2, HCHO, CO, aerosols, CO2, methane
• Global continuous view from L-1 critical for observation of hemispheric pollution, tropospheric background, greenhouse gases
• Bridge with interests of climate, upper atmosphere, space weather, solar physics communities
Satellites
OBSERVING SYSTEM FOR ATMOSPHERIC COMPOSITIONOBSERVING SYSTEM FOR ATMOSPHERIC COMPOSITIONMUST INTEGRATE SATELLITES, IN SITU MEASUREMENTS, AND MODELSMUST INTEGRATE SATELLITES, IN SITU MEASUREMENTS, AND MODELS
Surface monitors
Chemical transport
models
Aircraft, lidar
NEW KNOWLEDGE
Air quality monitoring& forecasting
Source quantification,policing of environ-mental agreements
Long-range transport
Climate forcing
Biogeochemical cycling
Weather forecasting
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