11

Lessons Learned From Lessons Learned From Aura/OMI- Implications for Aura/OMI- Implications for

TROPOMI TROPOMI

Pawan K. BhartiaPawan K. BhartiaLaboratory for AtmospheresLaboratory for Atmospheres

NASA Goddard Space Flight CenterNASA Goddard Space Flight CenterMaryland, USAMaryland, USA

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OMI Data SetsOMI Data Sets Stratospheric productsStratospheric products

• OO3 3 column & profilecolumn & profile• (BrO column and OClO slant columns are being produced but have not (BrO column and OClO slant columns are being produced but have not

been extensively studied)been extensively studied) Free-Tropospheric productsFree-Tropospheric products

• Trop OTrop O33, Aerosol Index, volcanic SO, Aerosol Index, volcanic SO22

• (lightning NO(lightning NO2 2 and pollution SOand pollution SO22 have been observed) have been observed) PBL productsPBL products

• NONO22, HCHO, BrO, HCHO, BrO• (aerosols can be measured under cloud-free conditions, CHOCHO has (aerosols can be measured under cloud-free conditions, CHOCHO has

been observed)been observed) Climate & Radiation ProductsClimate & Radiation Products

• Radiative cloud fraction (an index of cloudiness) Radiative cloud fraction (an index of cloudiness) • Aerosol absorption optical depthAerosol absorption optical depth• Radiative cloud pressure (sensitive to cloud structure)Radiative cloud pressure (sensitive to cloud structure)• Surface UVSurface UV

3

Tropospheric Ozone from OMI-MLS

MLS/OMI tropospheric ozone – monthly average July and October 2005, Ziemke et al., JGR 2006

24 and 28 June 2005

Global maps of tropospheric ozone showing effects of pollution in the Northern Hemisphere in summer and biomass burning in Southern Hemisphere in spring

Ozone pollution from North America to Europe or stratospheric ozone from a tropopause fold?

4

Deseasonalized Time Series

S.E. Pacific Tropical NorthAtlantic

Costa Rica

EasternAfrica

Indonesia WesternAustralia

OMI: SOOMI: SO22 emissions from smelters and emissions from smelters and volcanoesvolcanoes

•• Daily monitoring of SODaily monitoring of SO22 emissions is emissions is

possible with OMI.possible with OMI.

• The Peruvian copper smelters are among The Peruvian copper smelters are among the world’s largest industrial point sources of the world’s largest industrial point sources of SOSO22. .

Ecuador/S. Colombia volcanoes

Ilo copper smelter

La Oroya copper smelter

Ilo

La Oroya

Carn Carn et al.et al., in prep, in prep

Peru Daily SODaily SO22 burdens for 3 source regions burdens for 3 source regions

Sept. 2004 - June 2005Sept. 2004 - June 2005

Average OMI SOAverage OMI SO22 vertical column vertical column

Sep 2004 - June 2005Sep 2004 - June 2005

Equador

Colombia

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Average (2005-2006) SOAverage (2005-2006) SO22 burdens over burdens over USA, Europe and , Europe and China China

25.5 million tons of SO2 was emitted by Chinese factories in 2005

up 27% from 2000

East-Aire’05 experiment

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Lessons Learned (1)Lessons Learned (1)

Total column ozone can be estimated with ~1% Total column ozone can be estimated with ~1% accuracy & 0.3% precision in clear areas and in accuracy & 0.3% precision in clear areas and in large fraction of cloudy areas.large fraction of cloudy areas.

Stratospheric ozone column can also be Stratospheric ozone column can also be estimated with similar accuracy & precision when estimated with similar accuracy & precision when the tropopause is relatively high (>10 km). the tropopause is relatively high (>10 km). • Such performance is needed for trop OSuch performance is needed for trop O33 studies. studies.

• Requires very good instrument performance between Requires very good instrument performance between 300-320 nm. 300-320 nm.

• OMI performance is much better than GOME but still not OMI performance is much better than GOME but still not optimal due to calibration and spectral straylight optimal due to calibration and spectral straylight problems.problems.

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Radiometric + Straylight Error Radiometric + Straylight Error Estimated Using MLSEstimated Using MLS

X-

trac

kX

- tr

ack

Stray light?Stray light?

UV2UV2

One day of MLS ZM O3 profile from tropics LLM climatology below 115 hPaSemi- analytical Ring corrn Low reflectivity data only

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OMI- MLS OOMI- MLS O33 Column Column

ComparisonsComparisons

1010

No Correction

With MLS-derived Radiance Correction

Accurate radiance calibration is critical for tropospheric ozone retrievals.

Impact of calibration error on Impact of calibration error on trop Otrop O33 retrieval retrieval

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Implications for TROPOMI (1)Implications for TROPOMI (1)

The instrument needs to be optimized for The instrument needs to be optimized for better performance, particularly for better performance, particularly for straylight, in the 300-320 nm wavelength straylight, in the 300-320 nm wavelength region.region.

The detectors shouldn’t be split at 310 nm, The detectors shouldn’t be split at 310 nm, as is the case with OMI. as is the case with OMI.

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Lessons Learned (2)Lessons Learned (2)

Effects of clouds on reflected wavelengths are Effects of clouds on reflected wavelengths are very different than at thermal IR wavelengths.very different than at thermal IR wavelengths.• Multi-layer and multi-phase clouds (mixed ice and water Multi-layer and multi-phase clouds (mixed ice and water

clouds) are far more common than previously believed, clouds) are far more common than previously believed, and they have significant effect on trace gas and aerosol and they have significant effect on trace gas and aerosol absorption.absorption.

• Knowledge of geometrical cloud fraction may not be Knowledge of geometrical cloud fraction may not be necessary or useful for the estimation trace gas and necessary or useful for the estimation trace gas and aerosol absorption from reflected sunlight instruments, aerosol absorption from reflected sunlight instruments, since measured reflectances apparently contain all the since measured reflectances apparently contain all the necessary information. necessary information.

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Clouds as seen by CloudSat, Clouds as seen by CloudSat, MODIR-TIR channels and OMI MODIR-TIR channels and OMI

MODIS cloud-top press

Cloudsat radar reflectivity

Cloud press calculated using OMI-measured Rot Raman Scattering. (O2-O2 absorption results from KNMI are similar.)

For well-mixed gases For well-mixed gases use of OMI-derived use of OMI-derived cloud pressure cloud pressure provides the correct provides the correct column amount. column amount.

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Validation of OMI’s Cloud Fraction ModelValidation of OMI’s Cloud Fraction Model

Sea-glintSea-glint

measmeascalccalc

Method:340/380 is affected primarily by cloud fraction, cloud optical depth, aerosols, and surface albedo, but not by cloud

structure/height.

Nimbus-7 TOMS data from the Pacific (March 20, 1979)

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Implications for TROPOMI (2)Implications for TROPOMI (2)

Multi-phase and multi-layer clouds can be Multi-phase and multi-layer clouds can be reliably detected by combining reflected reliably detected by combining reflected sunlight (Raman, Osunlight (Raman, O22-O-O22 or O or O22 A-band) with A-band) with thermal emission measurements. thermal emission measurements. • Detection of such clouds is important for estimating Detection of such clouds is important for estimating

trace gas and aerosol absorption in presence of trace gas and aerosol absorption in presence of clouds. clouds.

• Such clouds may affect surface radiation by Such clouds may affect surface radiation by increasing absorption by trace gases and aerosols increasing absorption by trace gases and aerosols due to multiple scattering.due to multiple scattering.

• Detection of such clouds is important for climate Detection of such clouds is important for climate studies.studies.

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Lessons Learned (3)Lessons Learned (3)

Aerosol (extinction) optical thickness (AOT) is very difficult to Aerosol (extinction) optical thickness (AOT) is very difficult to measure from OMI due to sub-pixel cloud contamination, measure from OMI due to sub-pixel cloud contamination, except in arid areas.except in arid areas.

Most aerosols have very strong absorption in the UV.Most aerosols have very strong absorption in the UV. Primary aerosol products from OMI are aerosol index (AI) and Primary aerosol products from OMI are aerosol index (AI) and

aerosol absorption optical depth (AAOT). aerosol absorption optical depth (AAOT). • AI is very useful for tracking smoke and dust aerosols over long-AI is very useful for tracking smoke and dust aerosols over long-

distances, since the method works even when aerosol plumes distances, since the method works even when aerosol plumes go over clouds and snow/ice.go over clouds and snow/ice.

• Aerosol height (center of mass altitude) is a critical parameter Aerosol height (center of mass altitude) is a critical parameter for the estimation of AAOT. for the estimation of AAOT.

• It may be possible to measure AAOT over clouds and snow/ice. It may be possible to measure AAOT over clouds and snow/ice.

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Aerosol Absorption increases in UVAerosol Absorption increases in UV

€

τ abs ∝ λ−k

k = 1 for for BC

≈ 2 for OC

~ 3 for Desert Dust

ττabs=0.05abs=0.05

BCBC

OCOCDustDust

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Smoke from Colorado fires (June 25, 2002)

Transport of Mongolian dust to N. America in April 2001. This image was made by compositing several days of TOMS data.

SmokeSmoke

Desert DustDesert Dust

Aerosol IndexAerosol Index

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Detection of Smoke over CloudsDetection of Smoke over Clouds

SeaWiFS True ColorTOMS Aerosol Index

Laos

Thailand

Vietnam

Southern China

Taiwan

21 March 1999

A Frequent Flyer+: the typical pathway

Cambodia

2020

SeaWiFS True ColorCERES short-wave flux

TOMS Aerosol Index

21 April 2001

FTOA = FTOA(CLD)

FTOA(CLD/SMK)

= ~200 Watts m-2

Effect of smoke over clouds on TOA radiationEffect of smoke over clouds on TOA radiation

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Implications for TROPOMI (3)Implications for TROPOMI (3)

Possible use of OPossible use of O22 A-band for the estimation of A-band for the estimation of aerosol height (center of mass altitude) need to aerosol height (center of mass altitude) need to investigated. investigated.

The focus of aerosol research from The focus of aerosol research from OMI/TROPOMI should be on understanding the OMI/TROPOMI should be on understanding the effects of absorbing aerosols on surface effects of absorbing aerosols on surface radiation and clouds, and not on duplicating radiation and clouds, and not on duplicating what high resolution visible sensors, such as what high resolution visible sensors, such as MODIS & MISR, do much better. MODIS & MISR, do much better.

2222

SUMMARYSUMMARY

Trop OTrop O33 studies require very good studies require very good instrument performance in the 300-315 nm instrument performance in the 300-315 nm range.range.

Combination of UV/VIS cloud information Combination of UV/VIS cloud information with thermal information can benefit with thermal information can benefit climate studies by detecting climate studies by detecting multi-layer/multi-phase clouds .multi-layer/multi-phase clouds .

Estimation of aerosol absorption from the Estimation of aerosol absorption from the UV/blue technique may greatly improve by UV/blue technique may greatly improve by adding Oadding O22 A-band to TROPOMI. A-band to TROPOMI.

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Tropospheric Equivalent Mixing Ratio

The high ozone feature off the east coast appears to be a fold - white contours show the tropopause gradient - not pollution. However, the magnitude of the fold tropospheric ozone event is very high….

5-day average

Ziemke et al. 2006

800 ppbv

Schoeberl et al., 2007

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NONO22 over India and Asia over India and Asia

March 2006 May 2006

July 2006 September 2006

Gleason et al.

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OMI CH2O (Formaldehyde)

CH2O is an indicator of VOC emission, which in combination with NOx cause O3 pollution

CH2O is an indicator of VOC emission, which in combination with NOx cause O3 pollution

Offshore CH2O?

VOCs emitted by forests under stressVOCs emitted by forests under stress

From Kurosu & Chance