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