Harmonizationof GOME, SCIAMACHY, GOME-2 ozone cross-sections Anna Serdyuchenko, John P. Burrows,...

Harmonization Harmonization of of

GOME, SCIAMACHY, GOME-2 GOME, SCIAMACHY, GOME-2 ozone cross-sectionsozone cross-sections

Anna Serdyuchenko, John P. Burrows, Mark Weber, Wissam Chehade

University of Bremen, Germany Institute of Environmental Physics

64th International Symposium on Molecular spectroscopy

Columbus, OH USA, June 22-26, 2009

University of Bremen, IUP, Molecular Spectroscopy Lab

2

Atmospheric species detection: Available spectrometers Time and space coverage

Available databases for the reference data: Laboratory measurements; Satellite spectrometers

measurements; Comparison of datasets.

Challenges of cross-section measurements in lab

Modern demands on the O3 absorption cross-section quality

University of Bremen, IUP, Molecular Spectroscopy Lab 3

• Long-term measurements of O3 (and NO2) are important for air quality study, Montreal Protocol monitoring of ozone depleting substances, climatology etc

• Long-term global data sets covering several decades are only available by combining datasets from multiple sensors:

GOME, GOME2: Global Ozone Monitoring Experiment SCIAMACHY: Scanning Imaging Absorption Spectrometer for

Atmospheric Chartography TOMS: Total Ozone Mapping Spectrometer OMI: Ozone Monitoring Instrument Ground based instruments: Brewer, Dobson spectrophotometers

• Monitoring:Troposphere: biomass burning, pollution, arctic haze, forest fires,

dust storms, industrial plumesStratosphere: ozone chemistry, volcanic events, solar proton

eventsClouds, aerosols, UV index


Satellite spectrometers measure the solar radiation transmitted, backscattered and reflected from the Earth atmosphere and surface, also direct sun light

Absorption spectra cover: O3 O2 NO2 N2O BrO OClO SO2 H2CO2 CO CO2 CH4 H2O

GOME, GOME2 (Global Ozone Monitoring Experiment): scanning 4 channels grating spectrometer with nadir-view

SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography): scanning 8 channels grating spectrometer with nadir/limb-view


•GOME / GOME2: Global Ozone Monitoring Experiment

•SCIAMACHY: Scanning Imaging Absorption Spectrometer for

Atmospheric Chartography

•MetOP: is a series of three satellites to be launched sequentially

(2006, 2010, 2020)

•At least two decades of observations with global coverage Spectrometer

Satellite Launched Spatial resolution, km

GOME ERS-2 April 1995 40 x 40 to 40 x 320

SCIAMACHY ENVISAT March 2002 Limb: 3 x 132Nadir: 32 x 215

GOME2 MetOp -A October 2006 40 x 80 to 40 x 240

MetOp - B June 2010 (plan)

Spurious instrumental trends in multiple instrument time series

GOME: no trend SCIAMACHY: -0.4%/year

State of the Climate in 2008, Bull. Amer. Meteor. Soc., submitted, 2009

Cross-section used:

GOME: Burrows et al. 1999

SCIAMACHY: Bogumil et al. 2003 (scaled)

SBUV/TOMS/OMI: Bass & Paur 1985

GOME/SCIAMACHY retrieval uses DOAS (differential spectral fitting) in 325-335 nm window

Dobson standard retrieval : AD pairs and CD pairs (similarly for TOMS)

A-pair: 305.5/325.4 nm C-pair: 311.5/332.4 nm D-pair: 317.6/339.8 nm

◦ Brewer standard retrieval uses Brewer wavelength ratio pairs formed from B0 to B4


Instrumental

Slit Function

Instrumental

Slit Function

Convolution

Convolution

O3 SpectrumO3 Spectrum

cross-sections measured with the satellite instrument



Data Retrieval and Analysis


Determination of O3 Columns in the Atmosphere


laboratory measurements of high resolution

cross-section spectra








Instrumental

Slit Function

Instrumental

Slit Function

Convolution

Convolution










HITRAN 2008


• For GOME, SCIAMACHY, and GOME2 flight models were used to measure absorption cross-section prior to launch: experimental set-up Calibration Apparatus for Trace Gas Absorption Spectroscopy (CATGAS);

• Slightly different resolution 0.17 -0.3 nm

• Advantage: exact match of spectral resolution between satellite radiance and cross-sections

• Knowledge for instrumental slit function is not needed


ODII exp0 I - transmitted intensity I0 - initial intensity - wave lengthOD - optical density

Red – absorption/baseline, Blue – lamp monitoring

UV/VIS : Xe, D2

Lamp

Calibration: HgCd

lamp

Detector: LN2 cooled

chip

Cell: 120 cm

long, 5 cm Dia

thermostatedevacuated


Data set Temperatures, KResolution, nm:

Wavelength covered, nm

GOME FM Burrows et al., 1999

202 221 241 273 293

0.17 @ 330 nm

230 - 800

SCIAMACHY FM Bogumil et al., 2003

203 223 243 273 293

0.20 @ 330 nm

230 - 2380

GOME2 FM Spietz et al., 2005

203 223 243 273 293

0.29 @ 330nm 240 – 790

Paur and Bass, 1985

203 218 228 243 273 298

<0.025 nm(?) 245 - 345

Malicet et al. 1995 Brion et al., 1993Daumont et al., 1992

218 228 243 273 295

0.01-0.02 nm 195-345

UV-FTSVoigt et al., 2001

203 223 246 280 293

0.03 @ 230 nm

230 - 850


cover broad spectral range (0.2-1.2 µm) cover most atmospheric temperatures BUT all above 200 K

Comparison of results from different instruments: adjustment of resolution is needed Data quality check (temperature dependence)

Minimization of residuals by comparison of O3: wavelength shifts , scaling

Cross-sections Shift [nm]Scaling

to Malicet, Brion, Daumont

Scaling to

GOME1

GOME FM +0.017(2) 1.027(2) -

SCIAMACHY FM +0.008(2) 0.970(3) 0.944

GOME2 FM3 -0.047(2) 0.950(7) 0.925

-5%

-8%

SCIAMACHY total O3 retrieval (using SCIAMACHY reference spectra) are 5% higher than GOME (with GOME reference spectra) in the range 325-335 nm

GOME2 total O3 retrieval (using GOME2 reference spectra) is 8% higher than calculated with resolution adjusted GOME FM reference data

Harmonisation of O3 flight model cross-sections from GOME and SCIAMACHY for a consistent retrieval

Two approaches:• reanalysis of laboratory data from the CATGAS campaigns• new laboratory measurements:

experience from the previous researchers of IUP: CATGAS GOME2 experimental set-up, Fourier Transform Spectrometer;

potential error sources analysis & modification of set-up and conditions set;

sufficient accuracy to detect a 1% pro decade trend


The overwhelming need for atmospheric measurements in the UV-Vis is to obtain improved cross-sections of ozone using FTS measurements; particular care has to be paid to avoid baseline uncertainties which are a major source of systematic errors in such measurements.

Wavelength coverage of 240–1000 nm is required, at 0.01 nm spectral resolution or better.

Absolute intensities should be accurate to at least 2% through the Hartley–Huggins and Chappuis bands.

Vacuum wavelength accuracy: better than 0.001 nm, reflecting the accuracy to which atmospheric spectra can be calibrated using correlation with the Fraunhofer spectrum.

Measurements should be made over the 180–300 K temperature range.

*J.Orphal, K.Chance .Ultraviolet and visible absorption cross-sections for HITRAN

Journal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 491–50417

• About two decades of observation from satellites spectrometers will be possible

• Three satellite spectrometers were calibrated by Bremen researchers.

• Several sets of absorption cross-sections produced, which include slit-functions.

• Disagreement between retrieved data to be corrected.

• Reanalysis of the data obtained during measurements campaigns

• New measurements

Work is supported by European Space Agency



• GOME2 FM3: At some temperatures deviation of 2% (223 K, 243K)

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Harmonizationof GOME, SCIAMACHY, GOME-2 ozone cross-sections Anna Serdyuchenko, John P. Burrows,...

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