Third International DOAS Workshop, Bremen, 20 - 22 March, 2006 Retrieval of BrO vertical Retrieval of BrO vertical distributions from SCIAMACHY distributions from SCIAMACHY limb measurements: limb measurements: Data quality assessment and algorithm Data quality assessment and algorithm improvements improvements A. Rozanov 1 , J. P. Burrows 1 , S. Kühl 2 , C. McLinden 3 , K. Pfeilsticker 2 , J. Pukite 2 , R. Salawitch 4 , B.-M. Sinnhuber 1 , C. Sioris 5 , T. Wagner 2 1 Instutute of Environmental Physics, University of Bremen, Germany 2 Instutute of Environmental Physics, University of Heidelberg, Germany 3 Meteorological Service of Canada, Toronto, Cananda 4 Jet Propulsion Laboratory, Pasadena, California, USA 5 Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
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A. Rozanov 1 , J. P. Burrows 1 , S. Kühl 2 , C. McLinden 3 ,
Retrieval of BrO vertical distributions from SCIAMACHY limb measurements: Data quality assessment and algorithm improvements. A. Rozanov 1 , J. P. Burrows 1 , S. Kühl 2 , C. McLinden 3 , K. Pfeilsticker 2 , J. Pukite 2 , R. Salawitch 4 , B.-M. Sinnhuber 1 , C. Sioris 5 , T. Wagner 2. - PowerPoint PPT Presentation
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Third International DOAS Workshop, Bremen, 20 - 22 March, 2006
Retrieval of BrO vertical distributions from Retrieval of BrO vertical distributions from SCIAMACHY limb measurements: SCIAMACHY limb measurements:
Data quality assessment and algorithmData quality assessment and algorithm improvementsimprovements
A. Rozanov1, J. P. Burrows1, S. Kühl2, C. McLinden3, K. Pfeilsticker2, J. Pukite2, R. Salawitch4, B.-M. Sinnhuber1,
C. Sioris5, T. Wagner2
1Instutute of Environmental Physics, University of Bremen, Germany2 Instutute of Environmental Physics, University of Heidelberg, Germany
3Meteorological Service of Canada, Toronto, Cananda4Jet Propulsion Laboratory, Pasadena, California, USA
5Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
BOOST: A joint intercomparison projectBOOST: A joint intercomparison project
Bromine Oxide in the lOwer STratosphere (BOOST)Bromine Oxide in the lOwer STratosphere (BOOST)
Project objectivesProject objectives Comparison of BrO vertical distributions retrieved from SCIAMACHY
limb measurements using different retrieval algorithms
Investigation of possible reasons for the disagreement between the retrievals identified in previous studies
Improvement of the existing retrieval algorithms (especially the retrieval quality in the lower stratosphere and the upper troposphere)
Investigation of the sensitivity of the retrieved profiles to the retrieval parameters such as initial profiles, cross sections, spectral corrections
Participating retrieval groupsParticipating retrieval groups IUP, University of Bremen: Alexei Rozanov IUP, University of Heidelberg: Sven Kühl Harvard-Smithsonian Center for Astrophysics (SAO): Chris Sioris
Main inversion procedure:• Measurement vector: differential
signal in all spectral points at all selected tangent heights
• State vector: trace gas number densities at altitude levels
• Solution: Information Operator or Optimal Estimation
Retrieval algorithm of the University of BremenRetrieval algorithm of the University of Bremen
shift, ring, 1/I0, /I0, I0-corrected O3 cross section, eta, zeta
tilt, I0-corrected O3 cross section
Temperature dependence
full O3 cross sections at 223 K and 243 K fitted
series of fits with O3 and NO2 cross sections at different temperatures
Regularizationweak statistical, smoothness
statistical sharp gradients are not permitted
Initial set of the limb states to be comparedInitial set of the limb states to be compared
Selection criteria (based on results from Selection criteria (based on results from Dorf at al., 2006):):
At the first stage of the project comparisons will be performed for the limb states collocated with selected balloon-borne DOAS measurements
For each balloon flight air mass trajectory calculations were done identifying the forward (being in the future w.r.t. the balloon flight) and the backward (being in the past w.r.t. the balloon flight) match with SCIAMACHY limb observations
List of selected balloon flights:List of selected balloon flights:
March 23rd, 2003; Kiruna (67.9oN, 21.1oE); 15:19 - 16:09
October 9th, 2003; Air sur l’Adour (43.7oN, 0.3oW); 15:39 - 17:09
March 24th, 2004; Kiruna (67.9oN, 21.1oE); 13:55 - 17:35
Stratospheric temperature at matching statesStratospheric temperature at matching states
Temperature dependence of BrO cross sectionsTemperature dependence of BrO cross sections
Backward match:Backward match: March 24th, 2004; 10:36 UT; Orbit 10798; State 9; 66oN,9oE
Forward match:Forward match: March 25th, 2004; 8:25 UT; Orbit 10811; State 9; 62oN, 38oE
Dependence on a priori informationDependence on a priori information
Balloon flight: Balloon flight: October 9th, 200315:39 - 17:09Air sur l’Adour 43.7oN, 0.3oW
SCIAMACHY limb:SCIAMACHY limb: October 10th, 20039:20 UTOrbit 8421, State 941oN, 15oE
University of Bremen retrievals:University of Bremen retrievals:
Dependence on a priori informationDependence on a priori information
University of HeidelbergUniversity of Heidelberg SAOSAO
ConclusionsConclusions
All retrievals agree within error barsAll retrievals agree within error bars Error bars of SAO retrievals are very large in the lower layers: 60
% at 17 km increasing downwards, often > 100% below 16 km Retrievals of Uni Heidelberg result in slightly higher values compared
to Uni Bremen retrievals over the whole altitude range Below 20 km SAO retrieval tend to produce higher values as
compared to Bremen and Heidelberg results
Dependence on a priori informationDependence on a priori information Below 20 km Uni Heidelberg retrievals show a dependence on a priori
profiles Below 17 km Uni Bremen retrievals show a dependence on the form of
a priori profiles but not on the absolute values SAO retrievals are found to be independent of the initial profile
Effect of cross sections is estimated to be about 10%Effect of cross sections is estimated to be about 10%
OutlookOutlook
Additional comparisons are needed Additional comparisons are needed Additional DOAS flight: June 17th, 2005 Balloon-borne in-situ measurements with TRIPLE Balloon born SAOZ measurements
Model simulations and retrievalsModel simulations and retrievals SCIATRAN (Uni Bremen) VECTOR (SAO) TRACY (Uni Heidelberg)
Further investigation of the influence of the initialisation Further investigation of the influence of the initialisation parametersparameters