Recalibrated Ozone Profiles from GOME-UV/Vis Nadir spectra

Silvia Tellmann, Mark Weber, Vladimir Rozanov,

and John Burrows

Institute of Environmental Physics/ Institute of Remote Sensing

University of Bremen

ERS-ENVISAT Symposium, Salzburg, 6-10 Sep 2004ERS-ENVISAT Symposium, Salzburg, 6-10 Sep 2004

• O3 nadir profiling in Bremen• Calibration Problems in FURM V5• Improved calibration correction

• low latitude approach• global approach

• Improved tropospheric retrieval• Conclusion

Overview

GOME O3 profile retrieval in Bremen

Full Retrieval Method (FURM): Optimal estimation and Kozlov information matrix approach & validation

with ozone sonde dataR. Hoogen, V.V. Rozanov, J.P. Burrows, Ozone Profiles from GOME Satellite Data: Algorithm

Description and First Validation, J. Geophys. Res., 104, 8263-8280, 1999.

R. Hoogen, V.V. Rozanov, K. Bramstedt, K.-U. Eichmann, M. Weber, and J.P. Burrows, Ozone profiles from GOME satellite data-I: Comparison with ozonesonde measurements, Physics and Chemistry of the Earth 24, 447-452, 1999.

Extensive validation of Version 5 with lidar and satellite dataK. Bramstedt, K.-U. Eichmann, M. Weber, V. Rozanov, and J. P. Burrows, GOME ozone

profiles: A global validation with HALOE measurements, Adv. Space Res. 29, 1637-1642, 2002.

K. Bramstedt, J. Gleason, D. Loyola, W. Thomas, A. Bracher, M. Weber, and J. P. Burrows, Comparison of total ozone from the satellite instruments GOME and TOMS with measurements from the Dobson network 1996-2000, Atmospheric Chemistry and Physics 3, 1409-1419, 2003.

G. Hansen, K. Bramstedt, V. Rozanov, M. Weber, and J.P. Burrows, Validation of GOME ozone profiles by means of the ALOMAR ozone lidar, Annales Geophysicae 21, 1879-1886, 2003.

A. Bracher, M. Weber, K. Bramstedt, S. Tellmann, J. P. Burrows, Long-term global measurements of ozone profiles by GOME validated with SAGE II considering atmospheric dynamics, J. Geophys. Res., accepted, 2004.

GOMEO3 profile retrieval in Bremen (II)

Application in scientific studies: Arctic ozone depletion, international field campaigns (OFP, THESEO2000), ozone miniholes

K.-U. Eichmann, K. Bramstedt, M. Weber, R. Hoogen, V.V. Rozanov, and J.P. Burrows, Structure of ozone mini-holes from GOME, European Symposium on Atmospheric Measurements from Space, Proc. ESAMS'99, ESA-WPP-161, 231-236, 1999.

K.-U. Eichmann, K. Bramstedt, M. Weber, V.V. Rozanov, R. Hoogen and J.P. Burrows, O3 profiles from GOME satellite data - II: Observations in the Arctic spring 1997 and 1998, Physics and Chemistry of the Earth 24, 453-457, 1999.

H. Bremer, M. von König, A. Kleinböhl, H. Küllmann, K. Künzi, K. Bramstedt, J. P. Burrows, K.-U. Eichmann, M. Weber, A. P. H. Goede, Ozone depletion observed by ASUR during the Arctic Winter 1999/2000, J. Geophys. Res. 107, 8277, doi:10.1029/2001JD000546, 2002.

K.-U. Eichmann, M. Weber, K. Bramstedt, and J.P. Burrows, Ozone depletion in the NH winter/spring 1999/2000 as measured by GOME-ERS2, J. Geophys. Res. 107, 8280, doi:10.1029/2001JD001148, 2002.

U. Klein, I. Wohltmann, K. Lindner, and K. F. Künzi, Ozone depletion and chlorine activation in the Arctic winter 1999/2000 observed in Ny-Ålesund, J. Geophys. Res., 107 (D20), 8288, doi:10.1029/2001JD000543, 2002.

Continued development: tropical retrieval (wavelength extension) and cloud/albedo effects, a-priori profile sensitivity

S. Tellmann, S., V.V. Rozanov, M. Weber, and J.P. Burrows, Improvements in the tropical ozone profile retrieval from GOME UV/vis nadir spectra, Adv. Space Res. 34, 739-743, 2004.

L. N. Lamsal, M. Weber, S. Tellmann, and J. P. Burrows, Ozone column classified climatology of ozone and temperature profiles based on ozonesonde and satellite data, J. Geophys. Res., accepted, 2004.

• calculate ozone on several altitude levels large number of parameters: n 70

• Develop the profile in a sum of eigenfunctions with proper truncation n 10

• Kozlov-Information-matrix-method combined with optimal estimation:

n

nnClimxx ~

(z)n

)(n

FURM inversion schemeO3-eigenvectors in altitude range

alti

tud

e [k

m]

O3-EV [-]

O3-eigenvectors in wavelength range

O3-

EV

[-]

Wavelength [nm]

Radiometric calibration problems

ratio of GOME solar spectra direct after launch and 5 years later

degradation dichroic mirror

Rat

io [

-]

etalon

Wavelength [nm]

240 400 600 800

1.0

0.8

0.6

0.4

• outgassing (mainly optical coatings e. g. dichroic mirror) change optical features

• etalon structures: contamination layers on cooled detectors (ice) varies in time spectral modulation

• UV degradation of the instrument: scan mirror is exposed to UV-radiation

• polarization degradation

FURM V5 empirical calibration

• wavelength range: 290 – 340 nm• broadband calibration correction to allow for UVdegradation Chebychev Polynomials

Channel 1

po

lyn

om

ials

[-]

wavelength [nm]

Chebychev Polynomials

0.1

-0.1

-0.3280 300 320

340

Deviations between model and measurement

resi

du

al [

-]

310300290280

wavelength [nm]

• differential corrections: NOT applied !!!! V5 restricted to wavelengths

nm 290 -0.2

0.0

0.2

0.4

Shortcomings in FURM V5

• lack of information in upper stratosphere (above 35-40 km)• problems in tropics where ozone maximum is shifted to higher altitudes wavelengths below 290 nm needed to enhance stratospheric information content

Chebyshev polynomials inadequate at short wavelengths

Sensitive to measurement

measurement sensitivity

Al t

i tu

de

[km

]

Sum of rows AK-Matrix [-]

60

40

20

01.0 1.40.2 0.6

ozone profiles in tropics

Alt

i tu

de

[km

]

FURMSAGEIIClimatology

50

30

40

20

O3-concentration

Tropical calibration correction

Diff. error

Differential sunnormalized radiance

GOMEModel

wavelength [nm]275 280 285 290

y_m

eas

[-]

275 280 285 290wavelength [nm]

residual & fit of diff. error

GOME - Model

5D-4

3D-4

1D-4

-1D-4

5D-4

3D-4

1D-4

-1D-4y_m

eas

– y_

mo

de

l [-

]

• large differential structures below 290 nm • strong filling-in of Fraunhofer lines

New corrections by differential fit:

Fit addition error term: a ~1/irradiance

1/irr & polynomial fit before ozone retrieval (prefit in Ch. 1)

High latitude calibration correction Ozone maximum in middle and high latitudes shifted to lower altitudes and

longer wavelengths

low differential structure of ozone absorption

strong correlations between broadband calibration

corrections and atmospheric parameter

change of broadband calibration correction required below 300 nm statistical investigation of residuals

Mean residuals 1997-2003 in comparison with HALOE

0.0 0.2

0.4

0.6

1.0

0.8

275 280 290 295 300

Res

idu

al [

-]

285

wavelength [nm]

Results from 1997

tropicsRel. Deviations Old

Rel. Deviations New

Relative deviations between standard version/new version and independent measurement from SAGE II (Stratospheric Aerosol and Gas Experiment II)

Old New

2(SAGE-GOME)/(SAGE+GOME)

50

Alt

itu

de

[km

]A

ltit

ud

e [

km]0.0

0.2

-0.2

0.3

-0.3

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6

Comparison of O3 [ppm] SAGE/FURM50

40

30

20

10

0.1

-0.1

40

50

40

30

20

30

20al

titu

de

[km

]

latitude [deg]-60 -40 -20 0 20 40 60

old results

new results

Results from 2003

New Results

No of Pixel

old results

No of Pixel

0.3

0.0

0.2

-0.2

-0.3

Alt

itu

de

[km

]A

ltit

ud

e [

km]

50

40

30

20

50

40

30

20

Relative deviations between SAGE II and FURM

Comparison of O3 [ppm] SAGE/FURM

50

45

40

35

30

25

20

15

alti

tud

e [k

m]

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.62(SAGE-GOME)/(SAGE+GOME)

Old New

0.1

-0.1

new results

latitude [deg]-60 -40 -20 0 20 40 60

Tropospheric retrieval

retrieved tropospheric ozone alwaysquite near to climatological values

averaging kernels (AKs) indicate where information in retrieved height level comes from

Aks for retrieval levels in troposphere

Averaging Kernels [-]al

titu

de

[km

]

O3 Conc

FURMSondeClimatology

alti

tud

e [k

m] 50

40

30

20

10

0

50

40

30

20

10

0

Ozone Profile Hohenpeissenberg

Tropospherical investigations

• Profile fit: spectral window too large to make accurate tropospheric ozone fit

• Use just channel 2 to improve tropospheric column fit

• Two step retrieval:1. Common ozone profile fit to get information about stratospheric constituents.2. Use fitted profile and investigate residual in channel 2 (~320-335 nm) troposphere here defined up to ECMWF thermal

tropopause Make new diff. fit of tropospherical ozone column, temperature and Ring (inelastic scattering)

Sensitivity in Channel 2

3O

Residual & FitResidualFit all param.

Trop. Col.New col.Old col.

Temp. Fit

Ring Fit

Rin

g W

F f

i t [

-]T

W

F f

it [

-]O

3 W

F f

it [

-]R

esid

ual

[-]

wavelength [nm]

320 322 324 326 330 332 334328-0.02

0.00

0.02

-0.002

0.000

0.002

0.04

0.00

0.02

-0.04

0.00

-0.02

Tropospherical Column Results Relative Deviations between O3–Sonde and climatology as well as FURM

Hohenpeissenberg 1997

Rel. deviations Sonde-Climatology [-]

Rel

. dev

iati

on

s S

on

de-

FU

RM

[-]

troposph. columns from profile retrieval

troposph. columns from differential fit in channel 2

regression line for profile fit

regression line for step 2 differential fit in channel 2

+

• in most cases improvements

• for very small differences to climatological value instabilities in differential fit (noise)

Conclusions

Stratospheric information content can be enhanced by combined calibration concept in short wavelength region using

• differential „dark current“ approach for tropics/southern anomaly

• residual fit for middle and high latitudes.

Tropospheric retrieval based upon two step approach • accurate stratospheric ozone fit• accurate fit of Ring & atm. Parameters • realistic climatological ozone profile form

Inclusion of new ozone a-priori climatology (Lamsal et al. 2004) Reprocessing of GOME 1995-2003 in preparation (funding?) First application to SCIAMACHY (Version 5)

A-priori profile sensitivity

IUP climatology (Lamsal et al., JGR, 2004) F&K (Fortuin and Kelder, JGR, 1998)

Improvement in the lowermost stratosphere with IUP climatologysee also talk by Lamsal et al. (Abstract 353) for details on IUP O3 climatology

23 August 2002

Hohenpeissenberg 1997

SCIAMACHY nadir application

limb retrieval V1.6 (Savigny et al., JAS, 2004)FURM nadir retrieval Version 5

there are still outstanding issues regarding calibrationVisit poster by Bramstedt et al. (3P08-6) for more details

23 August 2002