1. OBSERVATION OF ATMOSPHERIC COMPOSITION FROM SPACE Daniel J. Jacob, Harvard University

2. NASA Earth & Sun Spacecraft

3. STRATOSPHERIC OZONE HAS BEEN MEASURED FROM SPACE SINCE 1979 Method: UV solar backscatter Scattering by Earth surface and atmosphere   Ozone layer Ozone absorption spectrum  

4. ATMOSPHERIC COMPOSITION RESEARCH IS NOW MORE DIRECTED TOWARD THE TROPOSPHERE Tropopause Stratopause Stratosphere Troposphere Ozone layer 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

5. WHY OBSERVE TROPOSPHERIC COMPOSITION FROM SPACE? Monitoring and forecasting of air quality: ozone, aerosols Long-range transport of pollution Monitoring of sources: pollution and greenhouse gases solar backscatter thermal emission solar occultation lidar FOUR OBSERVATION METHODS: Global/continuous measurement capability important for range of issues: Radiative forcing

6. 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 atmosphere depends on vertical profile; need chemical transport and radiative transfer models   z

7. THERMAL EMISSION MEASUREMENTS (IR,  wave) EARTH SURFACE I (T o ) Absorbing gas ToTo T1T1  I (T 1 ) LIMB VIEW NADIR VIEW 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

8. 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

9. 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

10. ALL ATMOSPHERIC COMPOSITION DATA SO FAR HAVE BEEN FROM 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

11. TROPOSPHERIC COMPOSITION FROM SPACE: platforms, instruments, species SensorTOMSGOMEMOPITTMISRMODISAIRSSCIA- MACHY TESMLSOMIOCO Platform (launch) multi (1979-) ERS-2 (1995) Terra Aqua (1999) ( 2002) Envisat (2002) Aura (2004)2008 ozoneX (tro- pics) XXXX COXXXX CO 2 X CH 4 X NO 2 XXX HNO 3 X HCHOXX BrOXX aerosolXX

12. NASA AURA SATELLITE (launched July 2004) Aura MLS TES nadir OMI HIRDLS Direction of motion TES limb Polar orbit; four passive instruments observing same air mass within 14 minutes OMI: UV/Vis solar backscatter NO 2, HCHO. ozone, BrO columns TES: high spectral resolution thermal IR emission nadir ozone, CO limb ozone, CO, HNO 3 MLS: microwave emission limb ozone, CO (upper troposphere) HIRDLS: high vertical resolution thermal IR emission ozone in upper troposphere/lower stratosphere Tropospheric measurement capabilities:

13. OBSERVING TROPOSPHERIC OZONE AND ITS SOURCES FROM SPACE Nitrogen oxide radicals; NO x = NO + NO 2 Sources: combustion, soils, lightning Methane Sources: wetlands, livestock, natural gas Nonmethane VOCs (volatile organic compounds) Sources: vegetation, combustion CO (carbon monoxide) Sources: combustion, VOC oxidation Tropospheric ozone precursors

14. CONSTRAINING NO x AND REACTIVE VOC EMISSIONS USING SOLAR BACKSCATTER MEASUREMENTS OF TROPOSPHERIC NO 2 AND FORMALDEHYDE (HCHO) Emission NO h (420 nm) O 3, RO 2 NO 2 HNO 3 1 day NITROGEN OXIDES (NO x ) VOLATILE ORGANIC COMPOUNDS (VOC) Emission VOC OH HCHO h (340 nm) hours CO hours BOUNDARY LAYER ~ 2 km Tropospheric NO 2 column ~ E NOx Tropospheric HCHO column ~ E VOC Deposition GOME: 320x40 km 2 SCIAMACHY: 60x30 km 2 OMI: 24x13 km 2

15. K. Folkert Boersma (Harvard) TROPOSPHERIC NO 2 FROM OMI: CONSTRAINT ON NO x SOURCES October 2004

16. K. Folkert Boersma (Harvard) TROPOSPHERIC NO 2 FROM OMI: ZOOM ON U.S. AND MEXICO MILAGRO campaign, March 2006

17. 1996-2005 TREND IN NO x EMISSIONS SEEN FROM SPACE Van der A et al., in prep.

18. FORMALDEHYDE COLUMNS MEASURED BY GOME (JULY 1996) High HCHO regions reflect VOC emissions from fires, biosphere, human activity -0.5 0 0.5 1 1.5 2 2.5x10 16 molecules cm -2 South Atlantic Anomaly (disregard) detection limit

19. FORMALDEHYDE COLUMNS FROM OMI OVER U.S. (July 2005): biogenic isoprene is the principal reactive VOC OMI GEOS-Chem chemical transport model with best prior estimates of VOC emissions Dylan B. Millet (Harvard) and Thomas Kurosu (Harvard-SAO)

20. SEASONALVARIATION OF GOME FORMALDEHYDE COLUMNS reflects 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]

21. GOME JJA 1997 tropospheric columns (Dobson Units) TROPOSPHERIC 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 TESUV backscatter measurement from GOME Liu et al., 2006

22. TES 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

23. USING ADJOINTS OF CHEMICAL TRANSPORT MODELS TO INVERT FOR EMISSIONS WITH HIGH RESOLUTION MOPITT daily CO columns (Mar-Apr 2001) Correction to model sources of CO A priori emissions from Streets et al. [2003] and Heald et al. [2003] Monika Kopacz, Harvard Inverse of atmospheric model

24. (sensitivity) OBSERVING CO 2 FROM SPACE: Orbiting Carbon Observatory (OCO) to be launched in 2008 Polar-orbiting solar backscatter instrument, measures CO 2 absorption at 1.61 and 2.06  m, O 2 absorption (surface pressure) at 0.76  m: global mapping of CO 2 column mixing ratio with 0.3% precision Averaging kernel Pressure (hPa) OCO will provide powerful constraints on regional carbon fluxes

25. 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: GEOSTATIONARY ORBIT

26. LAGRANGE POINTS MISSION CONCEPTS L1: view full disk of sunlit Earth nadir obs as in geostationary continuous obs from sunrise to sunst L2: nighttime Earth continuous solar occultation measurements

27. PROPOSED L-1 MISSION TO NASA (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, NO 2, HCHO, CO, aerosols, CO 2, 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

28. Satellites OBSERVING SYSTEM FOR ATMOSPHERIC COMPOSITION MUST 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