Investigation of inorganic stratospheric bromine using balloon-borne DOAS measurements and model simulations [Elektronische Ressource] / presented by Marcel Dorf

Informations

• Publié par: ruprecht-karls-universitat_heidelberg
• Publié le: 01 janvier 2006
• Nombre de lectures: 8
• Langue: English
• Poids de l'ouvrage: 24 Mo

Extrait

Dissertation
submitted to the
Combined Faculties for the Natural Sciences and for Mathematics
of the Ruperto Carola University of Heidelberg, Germany
for the degree of
Doctor of Natural Sciences
presented by
M.Sc. - Physics: Marcel Dorf
born in: Bad Mergentheim
Oral examination: 21.12.2005Investigation of
Inorganic Stratospheric Bromine
using Balloon-Borne DOAS Measurements
and Model Simulations
Referees: Prof. Dr. Klaus Pfeilsticker
Prof. Dr. Frank ArnoldInvestigation of Inorganic Stratospheric Bromine using Balloon-Borne DOAS
Measurements and Model Simulations
Inorganic bromine is the second most important halogen effecting stratospheric ozone [WMO 2003].
Although the concentration of bromine in the stratosphere is about two orders of magnitude lower than
the concentration of chlorine, it currently contributes about 25% to global ozone loss due to its much
greater ozone depletion efficiency (factor of around 45) compared to chlorine.
In this study, stratospheric balloon-borne DOAS (Differential Optical Absorption Spectroscopy) mea-
surements of bromine-monoxide (BrO) were analysed and interpreted using the 3-D CTM (Chemical
Transport Model) SLIMCAT [Chipperfield and Pyle 1998] and a 1-D photochemical model. Photochemi-
cal changes were calculated along air mass trajectories which match the balloon data with SCIAMACHY
(SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) satellite observations in
order to produce a set of BrO profiles suitable for SCIAMACHY validation. Furthermore, DOAS BrO
observations were used to infer the trend of total inorganic stratospheric bromine, which peaked around
1998 at 21± 3 pptv and is consistently 3.5 to 5 pptv higher than the known trend in organic bromine
precursors (halons and methyl bromide) can account for. This discrepancy, the non-zero amount of
inorganic bromine observed around the tropopause and the rapid increase above the tropopause, all
indicate that short-lived organic bromine source gases have to be taken into account. These results were
confirmed by comparing the DOAS BrO data with different SLIMCAT model runs.
Moreover, previous discrepancies between DOAS OClO measurements and model comparisons
[Fitzenberger 2000] were removed and detailed model studies were used to investigate ozone loss on
specific days and the consistency of the known stratospheric photochemistry.
Untersuchung des Anorganischen Stratosph¨arischen Bromgehalts mittels
DOAS Ballonmessungen und Modellrechnungen
Anorganische Bromverbindungen sind die zweitwichtigsten Halogenverbindungen fur¨ den
stratosph¨ arischen Ozonabbau [WMO 2003]. Obwohl die Bromkonzentration in der Stratosph¨ are
fast zwei Gr¨ oßenordnungen kleiner als die Chlorkonzentration ist, tragt¨ Brom zur Zeit mit ca. 25% zum
weltweiten Ozonverlust bei, da es eine großere¨ Effizienz im Zerst¨ oren von Ozone hat (ca. 45 mal so groß)
als Chlor.
Die vorliegende Arbeit befaßt sich mit stratospha¨rischen DOAS (Differentielle Optische Absorptions
Spektroskopie) Ballonmessungen von Brommonoxid (BrO). Diese wurden mit Hilfe des dreidimension-
alen Chemischen Transport Modells SLIMCAT [Chipperfield and Pyle 1998] und eines eindimensionalen
photochemischen Modells interpretiert. Um die Ballonmessungen mit SCIAMACHY (SCanning Imaging
Absorption spectroMeter for Atmospheric CHartographY) Satellitenmessungen vergleichen zu ko¨nnen,
¨wurden die photochemischen Anderungen entlang Luftmassentrajektorien berechnet, und es wurde
ein Satz an BrO Profilen erzeugt, der zur Validierung von SCIAMACHY geeignet ist. Darub¨ erhinaus
wurden DOAS BrO Messungen dazu verwendet, den Trend des anorganischen Gesamtbromgehalts in der
Stratosph¨ are zu bestimmen, welches 1998 mit 21± 3 pptv seinen Maximalwert erreichte und durchweg
3.5bis5pptvgroßer¨ ist als der bekannte Trend der bromierten organischen Vorl¨aufersubstanzen
(Halone und Methylbromid) es erwarten la¨ßt. Diese Diskrepanz, zusammen mit dem beobachteten nicht
verschwindenden Anteil an anorganischem Brom an der Tropopause und dem raschen Anstieg darub¨ er,
deuten an, daß kurzlebige bromierte organische Quellgase beruc¨ ksichtigt werden mussen,¨ was auch durch
Vergleiche mit verschiedenen SLIMCAT Modell¨ aufen besta¨tigt wurde.
Weiterhin konnten bisher bestehende Unterschiede zwischen DOAS OClO Messungen and Modell-
vergleichen [Fitzenberger 2000] beseitigt werden. Die Konsistenz der bekannten stratosph¨ arischen
Photochemie wurde mit detaillierte Modellrechnungen ub¨ erpruft¨ und der Ozonverlust an einzelnen
Tagen berechnet.
34Contents
1 Introduction 1
2 Stratospheric Photochemistry and Dynamics 5
2.1 Dynamics of the Polar Stratosphere .............................. 8
2.1.1 Potential Temperature .................................. 8
2.1.2 Potential Vorticity .................................... 9
2.1.3 The Vortex Edge ..................................... 10
2.1.4 The Northern and Southern Polar Vortex ....................... 10
2.1.5 Planetary Waves ..................................... 11
2.1.6 Stratospheric Warmings ................................. 12
2.2 Stratospheric Chemistry ..................................... 12
2.2.1 Ozone Chemistry ..................................... 13
2.2.2 Stratospheric Nitrogen Chemistry ........................... 15
2.2.3 Halogen Chemistry and Source Gases ......................... 18
2.2.4 Heterogeneous Chemistry on PSCs - The Ozone Hole ................ 25
2.2.5 Heteous Chemistry on Sulfate Aerosoles .................... 29
3 Methodology 31
3.1 Basics of the Atmospheric Radiative Transfer ......................... 31
3.1.1 Definitions ........................................ 31
3.1.2 Photochemical Effects .................................. 32
3.1.3 Scattering ......................................... 32
3.1.4 Absorption ........................................ 33
3.2 Solar Radiation and the Solar Spectrum ............................ 34
3.3 DOAS - Differential Optical Absorption Spectroscopy .................... 35
3.4 Spectral Retrieval......................................... 36
3.4.1 Sources of Errors ..................................... 39
4 Instrumentation 45
4.1 The LPMA/DOAS Balloon Payload .............................. 45
4.1.1 The LPMA Fourier Transform Interferometer ..................... 45
4.1.2 The DOAS Balloon Spectrograph............................ 46
4.1.3 mini-DOAS ........................................ 50
4.2 Instrumental Effects and Sun-Tracker Correlations ...................... 51
4.2.1 Instrumental Deficits................................... 51
4.2.2 Sun-Tracker Correlations ................................ 53
i5 Laboratory Reference Spectra 57
5.1 Experimental Setup ....................................... 58
5.2 O Reference ........................................... 603
5.3 BrO Reference .......................................... 61
5.4 NO and HONO Reference ................................... 622
5.5 OClO Reference ......................................... 65
5.6 Summary and Effect on Retrieval ................................ 65
6 Stratospheric BrO Profiling 69
6.1 Experimental Details of the BrO Evaluation.......................... 69
6.1.1 The DOAS BrO-Retrieval ................................ 69
6.1.2 Langley Plot ....................................... 73
6.1.3 BrO-Retrieval Error ................................... 76
6.2 Profile Retrieval ......................................... 76
6.2.1 Inversion Techniques ................................... 77
6.2.2 Errors of the Raytracing................................. 79
6.2.3 BrO Profile Inversion and Errors ............................ 79
6.3 Discussion of LPMA/DOAS Balloon Flights.......................... 82
6.3.1 LPMA / DOAS Flight on August 21/22, 2001 at Kiruna............... 85
6.3.2 LPMA / DOAS Flight on March 23, 2003 at Kiruna ................. 90
6.3.3 LPMA / DOAS Flight on October 09, 2003 at Aire sur l’Adour........... 95
6.3.4 LPMA / DOAS Flight on March 24, 2004 at Kiruna ................. 99
6.3.5 LPMA / DOAS Flight on June 17, 2005 at Teresina .................103
7 Validation of SCIAMACHY BrO Limb Profiles 107
7.1 Balloon-Borne and Satellite BrO Measurements ........................108
7.1.1 Resonance Fluorescence BrO Measurements ......................108
7.1.2 SAOZ BrO Measurements ................................109
7.1.3 SCIAMACHY BrO Profile Retrieval ..........................109
7.2 Modelling .............................................110
7.2.1 Trajectory Modelling...................................110
7.2.2 Chemical Modelling ...................................112
7.3 Further Constraints on the Photochemical Modelling .....................114
7.3.1 Photochemical Modelling and its Constraints .....................115
7.4 Results and Discussion......................................119
7.5 Conclusions ............................................123
8 Stratospheric OClO 129
8.1 OClO Evaluation .........................................130
8.2 The LPMA / DOAS Measurements at Kiruna on February 14, 1997 ............135
8.3 The LPMA / DOAS Measurements at Kiruna on February 10, 1999 ............139
8.4 The LPMA / DOAS Measurements at Kiruna on February 18, 2000