Validation of SCIAMACHY Level-1 and Level-2 Products by
Balloon-Borne Differential Optical Absorption Spectroscopy (DOAS)
Dorf M.1, A. Butz1, H. Bösch4, C. Camy-Peyret2, M. Chipperfield3, K. Gerilowski6, K.
Grunow5, W. Gurlit6, L. Kritten1, S. Kühl1, S. Payan2, A. Rozanov6, C. von Savigny6, B.
Simmes1, C. Sioris7, F. Weidner1 and K. Pfeilsticker1
(1) Institut für Umweltphysik (IUP), University of Heidelberg, Heidelberg, Germany
(2) Laboratoire de Physique Moléculaire pour l'Atmosphère et l'Astrophysique (LPMAA), Université Pierre et Marie
Curie, Paris, France
(3) Institute for Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK
(4) Jet Propulsion Laboratory, Pasadena, United States
(5) Meteorologisches Institut, Freie Universität Berlin, Berlin, Germany
(6) Institut für Umweltphysik (IUP), University of Bremen, Bremen, Germany
(7) Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
Institut für Umweltphysik, University of Heidelberg, Germany
DOAS Instruments onboard the LPMA / DOAS Balloon Gondola
LPMA: Limb Profile Monitor of the Atmosphere (FT-IR instrument)
DOAS: Differential Optical Absorption Spectroscopy
‘Big’- DOAS instrument (direct Sun):
Mini-DOAS instruments (Nadir & Limb):
• 2 grating spectrometers in one thermostated
(273 K) and evacuated housing
• Cooled photo diode detectors (1024 diodes, T =
- 260 K)
• Wavelength ranges and resolution:
• UV (316 - 418 nm, Δλ = 0.5 nm)
• Visible (400 - 653 nm, Δλ = 1.3 nm)
• Light intake: Solar tracker and glas fibre
bundle
• Efficient spectrometer stray-light suppression
• Solar occultation
• Total mass 45 Kg
• Total power consumption ~20 W
• Target species: O3, O4, H2O, NO2, OClO, BrO,
IO, OIO, and solar irradiance
• 2 grating spectrometers in one thermostated
(273 K) housing
• Cooled linear silicon CCD array
• (2048 pixels, T = 273 K)
• Wavelength range and resolution:
(320 - 520 nm, Δλ = 0.8 nm)
• Light intake: Glass fibre bundles
• NADIR and LIMB (+1 to -5o) observations
• Total mass 5 kg
• Total power consumption ~5 W
• Target species: O3, O4, NO2, BrO, nadir and
limb radiance, possibly OClO,
mini-DOAS can be operated on different
balloon platforms
Institut für Umweltphysik, University of Heidelberg, Germany
LPMA / DOAS Oberservation Mode
Balloon ascent
Solar occultation
Institut für Umweltphysik, University of Heidelberg, Germany
SCIAMACHY Observation Mode
• Sun synchronous low Earth orbit
• Overpass around 10:30 LT
• Vertical resolution of limb scan ~ 3.3 km
• Global coverage every 3 days
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of SCIAMACHY Limb Profiles
Comparison of SCIAMACHY and DOAS viewing geometry
SLIMCAT 3D-CTM
[M. Chipperfield]
Diurnal variation of e.g. BrO and NO2, and spatial and temporal mismatch prevent direct
comparison  Photochemical modelling is necessary !
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of SCIAMACHY Limb Profiles – Meteorological Forcasting / Analysis
Air mass trajectory calculations for the LPMA / DOAS flight at Air sur l`Adour (France) Oct. 09, 2003
• Find best coincidences satellite and balloon observ.
• Powerfull tool for flight planning
• Necessary to calculate photochemical changes
Plots courtesy of Katja Grunow (FU-Berlin)
Institut für Umweltphysik, University of Heidelberg, Germany
Validation Strategy
1.
2.
3.
4.
Conduct balloon flights for as many different geophysical condition as possible
Calculate matches of collocated ENVISAT / SCIAMACHY overpasses
Retrieve SCIAMACHY Limb profiles for the corresponding overpasses
Calculate photochemical corrections for the balloon observation on calculated air
mass trajectories
 Finally: Compare profiles !
Institut für Umweltphysik, University of Heidelberg, Germany
LPMA / DOAS / mini-DOAS Balloon Flights Performed for the Validation
of EnviSat / SCIAMACHY
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 1 Products – The Solar Irradiance Spectrum
Irradiance spectra referenced to Modtran 3.7 (updated Kurucz spectrum - Fontenla et al. 1999)
• Previous ESA SCIAMACHY
calibration 15% larger
• Significantly improved by
using IUP-Bremen re-calibration
• Agreement of SCIAMACHY:
(415–585)nm
- 0.4%
(370–415)nm
- 1.6%
(325–370)nm
- 5.7%
Absolute calibration performed by IUP – Bremen
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 1 Products – Radiative Transfer Models
Limb radiances measured by mini-DOAS: azimuth of 90° and elevation of +0.5° during balloon ascent
Comparison with RT modelling using:
TRACY : IUP – Heidelberg
SCIATRAN : IUP – Bremen
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – BrO Profiles
DOAS:
30
Aire sur l'Adour
a)
-
October 09, 2003
b)
[Bry] = (20.1 ± 2.8) pptv
DOAS uncorrected
Backward
DOAS corrected
Model balloon:
SZA = 72.9° (pm)
Model SCIAMACHY: SZA = 51.8° (am)
Model Bry: 43.6°N 0°E
SCIAMACHY: Orbit 8407 / 09:51 UT
25
Altitude / [km]
20
15
30
Forward
c)
DOAS uncorrected
DOAS corrected
Model balloon:
SZA = 72.9° (pm)
Model SCIAMACHY: SZA = 51.7° (am)
Model Bry: 43.6°N 0°E
SCIAMACHY: Orbit 8421 / 09:20 UT
d)
25
20
15
0.0
0.5
1.0
1.5
2.0
2.5
3.0
7
3.5
4.0
4.5
3
BrO Concentration / [10 molecule / cm ]
0
5
10
15
20
25
BrO Mixing Ratio / [pptv]
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – BrO Profiles
DOAS:
30
Aire sur l'Adour
a)
-
October 09, 2003
DOAS uncorrected
Backward
DOAS corrected
Model balloon:
SZA = 72.9° (pm)
Model SCIAMACHY: SZA = 51.8° (am)
Model Bry: 43.6°N 0°E
b)
[Bry] = (20.1 ± 2.8) pptv
25
SCIAMACHY: Orbit 8407 / 09:51 UT
IUP - Heidelberg
IUP - Bremen
Harvard-Smithsonian
Altitude / [km]
20
15
30
Forward
c)
DOAS uncorrected
DOAS corrected
Model balloon:
SZA = 72.9°
Model SCIAMACHY: SZA = 51.7°
Model Bry: 43.6°N 0°E
d)
(pm)
(am)
25
SCIAMACHY: Orbit 8421 / 09:20 UT
IUP - Heidelberg
IUP - Bremen
Harvard-Smithsonian
20
15
0.0
0.5
1.0
1.5
2.0
2.5
3.0
7
3.5
4.0
4.5
3
BrO Concentration / [10 molecule / cm ]
0
5
10
15
20
25
BrO Mixing Ratio / [pptv]
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – BrO Profiles
DOAS:
30
Kiruna
a)
-
March 24, 2004
Backward b)
25
[Bry] = (20.1 ± 2.8) pptv
DOAS uncorrected
DOAS corrected
Model balloon:
SZA = 77.1° (pm)
Model SCIAMACHY: SZA = 68.3° (am)
Model Bry: 67°N 22°E
SCIAMACHY: Orbit 10798 / 10:35 UT
20
Altitude / [km]
15
10
30
DOAS uncorrected
Forward
DOAS corrected
Model balloon:
SZA = 77.1° (pm)
Model SCIAMACHY: SZA = 61.8° (am)
Model Bry: 67°N 22°E
SCIAMACHY: Orbit 10811 / 08:24 UT
c)
25
d)
20
15
10
0.0
0.5
1.0
1.5
2.0
2.5
3.0
7
3.5
4.0
4.5
3
BrO Concentration / [10 molecule / cm ]
0
5
10
15
20
25
BrO Mixing Ratio / [pptv]
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – BrO Profiles
DOAS:
30
Kiruna
a)
-
March 24, 2004
Backward b)
25
(pm)
(am)
[Bry] = (20.1 ± 2.8) pptv
DOAS uncorrected
DOAS corrected
Model balloon:
SZA = 77.1°
Model SCIAMACHY: SZA = 68.3°
Model Bry: 67°N 22°E
20
SCIAMACHY: Orbit 10798 / 10:35 UT
IUP - Heidelberg
IUP - Bremen
Harvard-Smithsonian
Altitude / [km]
15
10
30
DOAS uncorrected
Forward
DOAS corrected
Model balloon:
SZA = 77.1° (pm)
Model SCIAMACHY: SZA = 61.8° (am)
Model Bry: 67°N 22°E
c)
25
d)
Janis Pukite (Heidelberg)
Tues.: 11.30am
20
SCIAMACHY: Orbit 10811 / 08:24 UT
IUP - Heidelberg
IUP - Bremen
Harvard-Smithsonian
15
Alexei Rosanov (Bremen)
Tues.: 10am
10
0.0
0.5
1.0
1.5
2.0
2.5
3.0
7
3.5
4.0
4.5
3
BrO Concentration / [10 molecule / cm ]
0
5
10
15
20
25
BrO Mixing Ratio / [pptv]
Institut für Umweltphysik, University of Heidelberg, Germany
Altitude / km
Validation of Level 2 Products – O3 Profiles
Kiruna, March 23, 2003, sunset
35
DOAS unsmoothed
DOAS smoothed
LPMA unsmoothed
SCIAMACHY
O3 sonde onboard
O3 sonde stand-alone
30
forward
35
30
25
25
20
20
Systematic underestimation at
24 to 28 km:
• Still tangent height error?
Underestimation below 20 km:
• Lower sensitivity of satellite
15
10
15
• Unaccounted horizontal trace
gas variations
10
backward
0
2
4
6
8 0
2
4
6
8
12
3
12
3
O3 concentration / (10 molecules/cm ) O3 concentration / (10 molecules/cm )
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – O3 Profiles
35
/
/
/
/
Altitude / km
30
Kiruna, 04 Mar 2003, sunset
Kiruna, 23 Mar 2003, ascent
Kiruna, 23 Mar 2003, sunset
Aire s. l'Adour, 09 Oct 2003, ascent
Kiruna, 24 Mar 2004, ascent
Kiruna, 24 Mar 2004, sunset
± 20% agreement in the 20 to
30 km range
25
20
15
10
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
2
3
[O3 Concentration(Balloon)/O3 Concentration(SCIAMACHY)]-1
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – NO2 Profiles
Kiruna, March 24, 2004, sunset
35
backward
forward
30
35
30
Altitude / km
•Underestimation below 20 km
25
25
20
20
15
10
DOAS uncorrected
DOAS corrected
SCIAMACHY
(IUP-Bremen)
SCIAMACHY
(Harvard)
SCIAMACHY
(IUP-Heidelberg)
0.0
0.5
1.0
1.5
2.0
2.5
9
3
NO2 concentration / (10 molecules/cm )
•Disrecpancies of the different
retrievals below 20 km
15
10
0.0
0.5
1.0
1.5
9
2.0
2.5
3
NO2 concentration / (10 molecules/cm )
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – NO2 Profiles
± 20% agreement in the 20 to
30 km range
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – mini-DOAS Limb Scanning Mode
SZA
4
65
59
53
47
41
37
33
30
29
30
33
O3
mini-DOAS deployed on:
MIPAS – B2 and
LPMA / IASI
-2
SCD NO2 [cm ] *10
-2
SCD O3[cm ] *10
12
16
19
72
8
4
NO2
Modelled
Measured
3
2
11:00
12:00
13:00
14:00
15:00
16:00
UT
Institut für Umweltphysik, University of Heidelberg, Germany
Validation of Level 2 Products – miniDOAS Limb Scanning Mode
72
65
59
53
47
41
SZA[°]
37
33
30
29
30
33
45
Altitude [km]
40
O3
30
25
20
15
40
3
0
1.0
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
35
45
10
Altitude [km]
12
10 molec/cm
NO2
Envisat/SCIAMACHY
overpass
#17412
#17441
9
30
25
20
15
10
12:00
3
10 molec/cm
35
11:00
Direct satellite match is
possible!
13:00
14:00
Time[UT]
15:00
16:00
0
0.0
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
Institut für Umweltphysik, University of Heidelberg, Germany
Summary and Conclusions
Results of the so far 5 validation flights:
•
Overall reasonable agreement fot level 1 products (solar irradiance and limb
radiance) of < ± 5 %, with updated SCIAMACHY irradiance calibration
•
Variable good agreement is obtained for level 2 (not yet operational)
products (BrO, NO2 and O3) inferred from IUP-Heidelberg, IUP-Bremen and
Harvard-Smithsonian
•
In gerneral comparisons indicate an accuracy of: ± 20 % for O3 and NO2
•
For BrO a bias of – 20 % / + 20 % is observed for above / below 25 km
(Harvard – Smithsonian retrieval only)
•
Air mass trajectory calculations prove to be a powerful tool for satellite
validation – for flight planning and for calculation of photochemical change
Upcoming activities:
•
Validation of level 2 products OCLO (at high-latitudes) and O3, NO2, BrO,
IO... (at low-latitudes)
•
Validation of complementary data products from EnviSat - MIPAS and
GOMOS
•
Results are also of value for existing satellite measurements, e.g. OMI, or
future validation activities, e.g. GOME – 2
Institut für Umweltphysik, University of Heidelberg, Germany
Publications so far
•
Butz, A., H. Bösch, C. Camy-Peyret, M. Chipperfield, M. Dorf, G. Dufour, K. Grunow, P. Jeseck, S. Kühl, S. Payan, I. Pepin, J. Pukite, A. Rozanov,
C. von Savigny, C. Sioris, F. Weidner, K. Pfeilsticker, Inter-comparison of stratospheric O3 and NO2 abundances retrieved from balloon-borne
direct sun observations and Envisat/SCIAMACHY limb measurements, Atmos. Chem. Phys., 6, 1293 -1314, 2006.
•
Dorf, M., H. Bösch, A. Butz, C. Camy-Peyret, M. P. Chipperfield, A. Engel, F. Goutail, K. Grunow, F. Hendrick, S. Hrechanyy, B. Naujokat, J.-P.
Pommereau, M. Van Roozendael, C. Sioris, F. Stroh, F. Weidner, and K. Pfeilsticker, Balloon-borne stratospheric BrO measurements:
Comparison with Envisat / SCIAMACHY BrO limb profiles, ACP (revised) 2006.
•
Gurlit, W., H. Bösch, H. Bovensmann, J. P. Burrows, A. Butz, C. Camy-Peyret, M. Dorf, K. Gerilowski, A. Lindner, S. Noel, U. Platt, F. Weidner,
and K. Pfeilsticker, The UV-A and visible solar irradiance spectrum: Inter-comparison of absolutely calibrated, spectrally medium resolved solar
irradiance spectra from balloon-, and satellite-borne measurements, Atmos. Chem. Phys., 5, 1879–1890, 2005.
•
Weidner, F., H. Bösch, H. Bovensmann, J. P. Burrows, A. Butz, C. Camy-Peyret, M. Dorf, K. Gerilowski, W. Gurlit, U. Platt, C. von Friedeburg, T.
Wagner, and K. Pfeilsticker, Balloon-borne Limb profiling of UV/vis skylight radiances, O3, NO2, and BrO: Technical set-up and validation of the
method, Atmos. Chem. Phys., 5, 1409–1422, 2005.
•
And various Ph.D. and Master theses
Institut für Umweltphysik, University of Heidelberg, Germany