Anna Serdyuchenko, Victor Gorshelev,
Wissam Chehade, John P. Burrows, Mark Weber
University of Bremen, Institute for Environmental Physics
HARMONICS Final Meeting - ESRIN, Frascati
1. HARMONICS project goals
2. Measurements of cross-section in laboratory: setup
3. Results analysis
4. Outlook
HARMONICS Final Meeting - ESRIN, Frascati
HARMONICS project goals
New measurements of cross-section in laboratory
Results analysis
HARMONICS Final Meeting - ESRIN, Frascati
T[K]
Shift
[nm]
Scaling
[-]
Gaussian
FWHM, [nm]
FWHM from solar
fits, [nm]
Scaling wrt.
GOME FM
Burrows et al. 1999
GOME FM
225
240
+0.017(2)
+0.017(2)
1.027(2)
1.023(2)
0.158(5)
0.159(6)
0.165(8)
-
Bogumil et al. 2003
SCIAMACHY FM
225
240
+0.008(2)
+0.009(2)
0.970(3)
0.973(3)
0.222(6)
0.219(6)
0.202(13)
-5.6%
-4.9%
Gür et al., 2005
GOME2 FM3
225
240
-0.031(3)
-0.031(3)
0.960(8)
0.949(7)
measured ILS
asymmetric ILS
(~0.29 nm)
-6.5%
-7.3%
Bass & Paur, 1985
(original, MPI database)
225
240
+0.020(3)
+0.023(5)
1.015(3)
1.000(3)
0.079(10)
0.087(10)
-
+1.2%
+2.3%
Bass & Paur, 1985
(ACSO web page, NASA)
225
240
+0.024(4)
+0.021(4)
1.004(3)
1.004(3)
0.084(12)
0.078(11)
-
+2.3%
+1.9%
Weber et al., 2011
Direct comparison by fitting cubic polynomial (DOAS type), a wavelength shift, and Gaussian slit function to
match DBM to other cross-sections:
 SCIAMACHY FM requires a scaling of +5% and GOME2 FM of +7% wrt to GOME in TO3 retrieval (Eskes
et al., 2005, Lerot et al., 2009, Weber et al., 2011)
 There are significant shifts between cross-sections (FMs and Bass-Paur),
▪
Note: total ozone change is -6DU/0.01nm shift (or -2%/0.01 nm) !!!
 advantage of satellite FMs: ILS does not need to be known
 disadvantage of satellite FM: Measurements were done at external facility under high time pressure
(satellite calibration period)
HARMONICS Final Meeting - ESRIN, Frascati
 SCIAMACHY total O3 retrieval (using SCIAMACHY FM reference spectra) were 5%
higher than GOME (with GOME FM reference spectra) in the range 325-335 nm (5%
direct cross-sections scaling wrt. GOME FM).
 GOME2 total O3 retrieval (using GOME2 FM3) is 9% higher than calculated with
resolution adjusted GOME FM. (7% direct cross-sections scaling wrt. GOME FM).
 Harmonisation of O3 and NO2 FM cross-sections from GOME and SCIAMACHY for a
consistent retrieval.
 Two approaches:
 reanalysis of data from the CATGAS campaigns;
 new laboratory measurements.
HARMONICS Final Meeting - ESRIN, Frascati
 Re-analyse the satellite FM cross-section data based upon available raw data from the
CATGAS campaigns (WP 100)
 GOME FM: no raw data available  will remain unchanged
 SCIAMACHY FM: raw measurement files are available  reanalysis
 GOME-2 FM3: raw measurement files are available reanalysis
 NO2: no need for change (stable gas conditions)
Note: FM cross-section data are relative measurements (need to be scaled to reference
data, here : BDM/BassPaur, alternative: new IUP)
 New laboratory measurements at IUP at high spectral resolution (UV to near IR)
 Verification of new results and total ozone retrieval tests
HARMONICS Final Meeting - ESRIN, Frascati

Importance of the cross-sections set choice is vigorously discussed last years within the
ozone observing community.

Quantum mechanical approach:
 a potential of producing a noise-free cross-sections.
 however, the quality of the ab initio calculations is still inferior to the experimental data accuracy.
 a comparison of calculated spectra with experimental high resolution data obtained in a wide spectral range
at different temperatures should play an important role in such studies.

Experimentally obtained ozone absorption cross-sections from pioneer works (1932)
until most recent studies: online spectral atlas of gaseous molecules of the
Max-Planck Institute for Chemistry, Mainz.

A large-scale initiative to review and recommend ozone cross-sections for all of the
commonly used atmospheric ozone monitoring instruments was started in spring 2009.
 Absorption Cross-sections of Ozone (ACSO) committee: a joint commission of the Scientific Advisory
Group of the Global Atmosphere Watch of the World Meteorological Organization (WMO-GAW) and the
International Ozone Commission (IO3C) of the International Association of Meteorology and Atmospheric
Sciences.
HARMONICS Final Meeting - ESRIN, Frascati
1. The high-resolution broadband data obtained by Bass and Paur (BP) :
 cover spectral region of 245 nm to 343 nm only.
 currently included in the standard ozone total column and profile retrievals using ground-based
(Brewer, Dobson) and satellite (SBUV, TOMS V8) spectrometers.
 included in the latest version of the high-resolution transmission molecular absorption database
HITRAN 2008; however, a wavelength shift must be applied.
2. The high-resolution broadband data by Brion, Daumont, Malicet (BMD)
 available for 195 nm - 830 nm for room temperature and for 194.5 nm - 520 nm for lower
temperatures down to 218K.
 subject of debates on substituting them for Bass and Paur data within the WMO-GAW and IGACO
community and in the next version of the HITRAN dataset.
 Currently data are used on the OMI and GOME GDP5 retrievals.
3. The high-resolution broadband cross-sections obtained by Bremen team
 Temperature-dependent absorption cross-sections at230-830 nm were recorded with a Fouriertransform spectrometer.
4. Measurements at single wavelengths: Axson (2011), Anderson (1993), Enami (2004), El Helou (2005),
Peterson (2012)
HARMONICS Final Meeting - ESRIN, Frascati
Recommendation on using the dataset on existing instruments and future missions is a
subject for research of many ozone investigating groups and nets around the world.
Nevertheless, few obvious criteria can be formulated:

spectral resolution at least order of magnitude better than the instrumental bandwidths
of modern remote sensing spectrometers;

wide spectral region to include spectral channels and windows of as many instruments
as possible;

availability of high quality experimental data at several temperatures going as low as
190K (ozone hole conditions).
HARMONICS Final Meeting - ESRIN, Frascati
Despite of the high quality of the already available data experimental works on the ozone
absorption spectra continue.
There are few important issues to be addressed:

improvement of the absolute accuracy of the cross-section up to 1-2% at least in the
Huggins band to answer the requirement to measure small changes in stratospheric and
tropospheric ozone;

improvement of the wavelength calibration;

improvement of the temperature dependence in the different spectral regions,
especially in the Huggins and Wulf bands;

measurements of the weak absorption in the bottom of the Huggins and Chapuis bands
and in the Wulf band NIR region longer than 900 nm, which were poorly covered so far.
HARMONICS Final Meeting - ESRIN, Frascati
 wavelength coverage UV/VIS/NIR
200 – 1000 nm;
 vacuum wavelength accuracy ~ 0.001 nm;
 spectral resolution ~ 0.02 nm;
 absolute intensities accuracy: 2%;
 temperature: 193K-293 K, step 10K
HARMONICS Final Meeting - ESRIN, Frascati
HARMONICS project goals
New measurements of cross-section in laboratory
Results analysis
HARMONICS Final Meeting - ESRIN, Frascati
Hartley
Huggins
Chappuis
Wulf
Spectral
region, nm
213 – 290
290 – 320
320 – 350*
350 – 450
450 – 500
500 – 800*
800 – 1100
Top
UV I
UV II
Bottom
Visible
NIR
IR
Echelle
FTS
FTS
Echelle
FTS
FTS
FTS
*absolute measurements
HARMONICS Final Meeting - ESRIN, Frascati
HARMONICS Final Meeting - ESRIN, Frascati
Setup VIS/IR
Setup UV/VIS
Spectrometer
Fourier Transform
Echelle (‘cross dispersion’)
Source
Xe and Tungsten lamps
Xe and D2 lamp
Detector
Si/GaP photodiode
ICCD
Resolution, FWHM
0.02 nm @ 300 nm
0.02 nm @ 300 nm
Wavelength region
290– 1100 nm
212 nm – 600 nm
Acquisition time
Slow (tens of minutes)
Fast (minutes)
Wavelength calibration
Excellent
(0.0005 nm in UV)
Excellent
(agrees with NIST Hg line at 253 nm better
than 0.001 nm )
Absorption path
135 and 270 cm
5 cm, 135 cm – 30 m
Cooling
Double jacket quartz cell, pre-cooler, cryogenic cooling
HARMONICS Final Meeting - ESRIN, Frascati
I ( )  I 0    e   N L
 ( )  OD( ) A
A  N  L,
N  p kT
I / I0
transmitted intensity with /without ozone
L
absorption path length, (1 – 20 m)
N/p
ozone density / pressure (1- 50 mbar)
k
Boltzmann constant
T
Temperature (200 – 300 K)
Art of uncertainty
Statistical uncertainty:
0.1-0.5%,
depends on spectral regions
Source
Reproducibility of spectra intensities I, I0:
- Source intensity drift;
- White noise;
- Fluctuations of temperature;
- Fluctuations of pressure.
Systematic uncertainty:
better than 3%,
independent on spectral regions
Absolute calibration parameters p, T, L, A:
- Purity of oxygen and ozone (leaks, ozone decay);
- Accuracy of temperature sensors;
- Temperature sensors off-set;
- Absolute accuracy of the cell length.
- Calibration procedure: Least squares fit coefficients
accuracy
HARMONICS Final Meeting - ESRIN, Frascati
Data
Scaling method
Hearn, 1961
Uncertainty, %
Statistical
Systematic
Total
Absolute , pure
ozone
-
-
2.1
BP, 1980 – 1985
Using
Hearn
1
?
2.3
Bogumil
(SCIAMACHY), 2003
Using BP
-
-
3.1*
Burrows (GOME),
1999
Absolute,
titration
Lamp drift
<2
2.6
2.6 – 4.6
Voigt, 2001
Integrated
GOME
BMD, 1992 - 1998
Absolute
(pure ozone)
3–6
0.9 –2
1.5 (420 –830 nm)
1.5–4 (350 –420 nm)
1.8 –2.5
1.8 –4.5
*excluding regions with the cross-section below 10-23 cm2/molecule (365 – 410 nm and longer than 950 nm) and 305320 nm
HARMONICS Final Meeting - ESRIN, Frascati
HARMONICS project goals
New measurements of cross-section in laboratory
Results analysis
HARMONICS Final Meeting - ESRIN, Frascati
Hartley
Huggins
(DOAS)
Chappuis
NIR
Minimum
Wulf
IR
HARMONICS Final Meeting - ESRIN, Frascati

Polynomial dependence on temperature:
•

Band-integrated cross-sections as functions of temperature (insensitive to resolution)
•


Bass-Paur parameterization (2nd order polynomial) for selected wavelengths in Huggins band
Hartley, Huggins, Chappuis bands
Comparison with existing datasets
•
High resolution datasets: Bass – Paur , Brion et al : wavelength shift, absolute scaling factor
•
Low resolution satellite datasets: resolution matching, wavelength shift, absolute scaling factor
Total ozone retrieval (Wissam Chehade)
Please note: comparison between cross-sections is not the same thing as
comparison between retrievals results!!!!
HARMONICS Final Meeting - ESRIN, Frascati
Nowadays, spectral channels of the
satellites-based (GOME, GOME-2,
SCIAMACHY, SAGE, SBUV, TOMS,
OMI, OSIRIS) and ground basedinstruments
(Brewer,
Dobson)
measuring ozone and other trace
gases cover a wide spectral range
from near UV to the visible and IR.
Ozone absorption spectrum in near
UV – near IR affects channels for
detection of other traces gases,
aerosols and clouds.
HARMONICS Final Meeting - ESRIN, Frascati
Hartley
Huggins
(DOAS)
Chappuis
NIR
Mean values are taken from
Orphal, J. (2003) A critical review of the absorption
cross-sections of O3 and NO2 in the ultraviolet and
visible. J. Photochem. Photobiol. A 157, 185-209;
IR
Minimum
Estimated experimental uncertainty is ~2%
245 – 340 nm
T, K Hartley band, x 10-16
203
223
243
273
293
Mean *
3.53 ± 1.2%
3.53 ± 1.1%
3.54 ± 1%
3.55 ± 1%
3.55 ± 0.6%
New**
3.52
3.53
3.53
3.54
3.53
325 – 340 nm
Huggins band, x 10-20
410 – 690 nm
Chappuis band, x 10-19
663 – 1000 nm
Wulf band, x 10-19
Mean
5.47 ± 3.3%
5.72 ± 2.6%
6.23 ±1.9%
7.26 ± 1.3%
8.23 ± 1%
Mean
6.48 ± 1.6%
6.35 ± 2.4%
6.35 ± 1.7%
6.44 ± 2.3%
6.38 ± 1.6%
New
0.991
0.999
1.006
1.028
New
5.46
5.74
6.30
7.35
8.30
HARMONICS Final Meeting - ESRIN, Frascati
New
6.30
6.31
6.33
6.38
6.36
1.04
Hartley
Huggins
HARMONICS Final Meeting - ESRIN, Frascati
Chappuis
Wulf
The spectral resolution of diverse ozone observing
instruments changes:
―with wavelength from the UV to the near IR
―from channel to channel for each instrument.
Instrument
FWHM
Channels
Dobson
1-3
306/325, 312/332, 318/340
Brewer
0.6
306, 310, 314, 317, 320
TOMS V8
1
312, 318, 331, 360
OMI
0.42 -0.63
264 - 504
OSIRIS
1
274 – 810
SBUV
1.13
256, 274, 283, 288, 292, 298, 302, 306, 313, 318, 331, 340
SAGE III
1.2 – 2.5
433-450, 53-622, 759-771, 933-960, 385, 676, 758, 869, 1020
HARMONICS Final Meeting - ESRIN, Frascati
BMD and BP – interpolated at 293K;
All datasets – resolution downgraded 1 nm
HARMONICS Final Meeting - ESRIN, Frascati

Mean Value, x 10-20
[nm]
J. Orphal, 2003
253.65
1141 ±0.9%
1126 ± 1.09%
289.36
149 ±2.0%
154 ± 0.67%
296.73
60.3 ±1.6%
61.60 ± 0.54%
302.15
29.2 ±1.8%
30.40 ± 0.48%
543.52
0.0314 ±1.3%
0.0316 ± 0.25%
576.96
0.0477 ±0.8%
0.0485 ± 0.20%
594.10
0.0470 ±1.2%
0.0474 ± 0.18%
604.61
0.0522 ±1.0%
0.0526 ± 0.2%
611.97
0.0466 ±0.7%
0.0468 ± 0.21%
632.82
0.0346 ±1.2%
0.0347 ± 0.18%
New data*, x 10-20
* Uncertainty of the experimental OD
HARMONICS Final Meeting - ESRIN, Frascati
Temperature dependence in UV region at
253.65 nm (Hartley band)
 Very weak temperature dependence (within 1%)
 Very good agreement with BMD, BP, GOME, SCIAMACHY FM revised, GOME-2 revised
HARMONICS Final Meeting - ESRIN, Frascati
HARMONICS Final Meeting - ESRIN, Frascati
 No resolution matching
 ‘Bass-Paur ’parametrisation
 328 nm “hill”, 330 nm “valley”
Black– New Data, Blue – BMD,
Magenta– SCIAMACHY
HARMONICS Final Meeting - ESRIN, Frascati
HARMONICS Final Meeting - ESRIN, Frascati
Comparison in Huggins band region: new data versus
high resolution datasets, relative difference and shifts
BP – Bass Paur, BMD – Brion et al
 2nd order polynomial inter/extrapolation 193-293K with step
of 10K
 inter/extrapolation on the common grid with step of 0.01 nm
 no resolution matching needed
 mean absolute deviation:
Green – comparison BP versus new experiment (325-340 nm);
Red – comparison BMD versus new experiment (325-345 nm);
Black – comparison BP versus BMD
BP –
BMD
BMD– New
Data
BP –New
Data
Shift, nm
0.02
0.005
0.02
Mean absolute
deviation
3%
1-2%
2-3%
HARMONICS Final Meeting - ESRIN, Frascati
Comparison in Huggins band region: new data versus
high resolution datasets, relative difference and shifts
2nd
dataset
Shift,
nm
Mean
integral
difference,
%
BPexp
+0.019
2.1/0.959
BMDexp
-0.012 1.6/0.985
BPcalc
+0.017
1.5/0.992
BMDcalc
BPHITRAN
+0.002
1.5/0.993
BPHITRAN BPcalc
BPHITRAN BPexp
0.015
0.017
BPcalc
BPexp
BPexp
-
BMDcalc
BMDexp
-
1st
dataset
this
work
this
work
this
work
Shift,
nm
Mean
integral
difference,
%
Bogumil
0.003
1.5
-0.015 1.4/0.997
Voigt
-0.006 1.04/0.979
-
-
-
-
-
0.01/1
0.4/0.998
BMDcalc
BMDexp
-0.014 1.3/0.998
-0.010 1.3/0.998
Voigt
-
0.007
-
1.1/1.013
-
0.002
-
0.4/0.998
-
BMDcalc
BMDexp
-0.029 1.3/0.998
-0.025 1.4/0.976
Voigt
Voigt
-0.022 1.1/1.013
-0.025 1.8/1.023
-
-
BMDexp
-
-0.005 0.02/1
-
Voigt
Voigt
0.007
0.002
2nd
dataset
Shift,
nm
Mean
integral
2nd
difference dataset
,%
-
HARMONICS Final Meeting - ESRIN, Frascati
0.9/1.018
1.2/0.993
Comparison in DOAS region: new data versus
SCIAMACHY (old and revised)
 Data convolved with
Gaussian slit function
 Disagreement ~ 1 – 5 %
for 241K, 273K and
293K, increasing at
lower temperatures.
 Wavelength shift of 0.005 to 0.015 nm.
 Deviation: within the
2% accuracy limits for
243K, 273K and 293K,
increase up to 5% for
203K, 223K.
HARMONICS Final Meeting - ESRIN, Frascati
Chappuis and Wulf bands
HARMONICS Final Meeting - ESRIN, Frascati
Direct comparison in the ‘minimum’
HARMONICS Final Meeting - ESRIN, Frascati
Chappuis band
SCIA FM revised
GOME-2 FM3 revised
HARMONICS Final Meeting - ESRIN, Frascati
Wulf Band
HARMONICS Final Meeting - ESRIN, Frascati
Wulf Band
SCIA FM revised
HARMONICS Final Meeting - ESRIN, Frascati
Wulf Band
Anderson, Mauersberger,
Journal of geophysical research 100(D2),
3033-3048, 1995
 Weak absorption, measurements are very
sensitive to the baseline and S/N, low
accuracy and precision -> FTS upgrade is
needed;
 Temperature dependence in NIR;
 Region is interesting for future missions
(SAGEII and SAGE III)
HARMONICS Final Meeting - ESRIN, Frascati
Advantages and limitations of the
new dataset
 High resolution: 0.02 nm@300 nm – 0.1 nm @ 1000 nm
 11 temperatures, down to 193K
 Spectral coverage UV- vis – NIR for all temperatures
 Accurate wavelength calibration, better than 0.001 nm
 Absolute accuracy:
 2 – 3% in UV/ visible,
 30% for 350 – 450 and 900 – 1050 nm
HARMONICS Final Meeting - ESRIN, Frascati
http://www.iup.uni-bremen.de/gruppen/molspec/databases/index.html
Data set
Resolution,
nm
Temperatures, K
Wavelength,
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 – 1070
GOME2 FM
Spietz et al., 2005
203
223 243 273 293
Paur and Bass, 1985
0.29 @ 330nm
240 – 790
203 218 228 243 273 298
<0.025 nm(?)
245 – 345
218 228 243 273 295
0.01-0.02 nm
195 – 345
Malicet et al. 1995
Brion et al., 1993
Daumont et al., 1992
UV-FTS
Voigt et al., 2001
IUP 2011
Serdyuchenko,
Gorshelev 2011
203
223 246 280 293
193 203 213 223 233 243
253 263 273 283 293
http:/
HARMONICS Final Meeting - ESRIN, Frascati
0.03 @ 230 nm 230 – 850
0.02 @330 nm 213 – 1050
Spring 2012: data
release
Spring 2011:
Retrievals
Summer 2009:
Autumn 2011 Winter2011/2012:
Publications preparation
Start of serial
measurements
Summer 2010Winter 2011:
Absolute
calibration
HARMONICS Final Meeting - ESRIN, Frascati
Starting from
summer 2012:
1. Feedback from
ozone investigating
groups and
organizations
2. Contact with
HITRAN database
―CH4 line parameters investigation (winter 2011-2012) (ESA
ADVANSE);
―Lab upgrade: dual-channel FT spectrometer (summer 2012)
(University of Bremen) ;
―Possible new measurements (starting from autumn 2012) :
Ozone: NIR and 10 mkm – staff support needed;
SO2 for UV sensors (320 nm) – staff support needed.
HARMONICS Final Meeting - ESRIN, Frascati
Special thanks to former IUP members: Peter Spietz
and Juan Carlos Gomez-Martin
Thank you for attention !
HARMONICS Final Meeting - ESRIN, Frascati