Airborne multi AXis DOAS instrument and measurements of two-dimensional tropospheric trace gas distributions [Elektronische Ressource] / presented by Klaus-Peter Heue

Kpheue

Informations

• Publié par: ruprecht-karls-universitat_heidelberg
• Publié le: 01 janvier 2006
• Nombre de lectures: 23
• Langue: English
• Poids de l'ouvrage: 18 Mo

Extrait

Dissertation
Submitted to the
Combined Faculties for Natural Sciences and for Mathematics
of the Ruperto-Carola University of Heidelberg, Germany
for the degree of
Doctor of Natural Sciences
Presented by:
Physicist: Klaus-Peter Heue
Born in: Baden-Baden
Oral Examination: 20.12.2005Airborne Multi AXis DOAS instrument and measurements of
two-dimensional tropospheric trace gas distributions
Referees: Prof. Dr. Ulrich Platt
Prof. Dr. Konrad MauersbergerAbstract
Airborne Multi AXis DOAS instrument and measurements of two-dimensional
tropospheric trace gas distributions
The Airborne Multi AXis DOAS instrument was developed and successfully operated during
four measurement campaigns. Depending on the purpose the instrument was installed on two
different aeroplanes flying either close to the tropopause or in the mixing layer.
In a detailed sensitivity study the possibilities of the measurements were investigated. For a
qualitatively good observation of tropospheric trace gases (e.g. NO and HCHO) additional2
information about the mixing layer height and the aerosol extinction is essential. This
information can be gained from either independent measurements or retrieved from the
measurements themselves. For example based on the O observation from different lines of4
sight the aerosol extinction can be estimated.
A very good agreement between tropospheric vertical NO columns for AMAXDOAS and2
SCIAMACHY measurements will be derived, if the AMF calculation is based on independent
observation. The linear correlation between the datasets results in a slope of 1 – 0.07.
Due to the measurement system the AMAXDOAS instrument is ideal for flux estimations.
For one flight just above the mixing layer the total HCHO production of Milano is estimated
24to 3.5*10 molec/s. In total the plume was 20 km wide.
A detailed plume study in lee of a power plant was performed. Here the different NO slant2
column densities were used for the reconstruction of a 2-dimensional trace gas distribution.
24The estimated flux originating from the power plant equals 2.5*10 molec/s.
Zusammenfassung
Flugzeug gest? tztes multi-axiales DOAS Instrument und Messungen zweidimensionaler
troposph? rischer Spurengasverteilungen
Ein flugzeuggest? tztes multi-axiales DOAS (AMAXDOAS) Instrument wurde entwickelt und
in vier Messkampagnen eingesetzt. Auf Grund der unterschiedlichen Ziele der
Messkampagnen wurde es auf unterschiedlichen Flugzeugen eingebaut. Die Standardflugh? he
war entweder nahe der Tropopause oder in der Grenzschicht.
F? r eine qualitativ hochwertige Interpretation der Messergebnisse ist eine m? glichst genaue
Kenntnis des Lichtweges notwendig, dieser wird unter anderem vom Aerosolgehalt
beeinflusst. Die Aerosolextinktion kann man entweder unabh? ngigen Messungen entnehmen
oder mittels der eigenen O -Messungen absch? tzen. Die Sensitivit? t des Instruments wurde4
f? r verschiedene Bedingungen untersucht.
Ein Schwerpunkt der Arbeit war die Validierung der mit SCIAMACHY gemessenen
vertikalen troposph? rischen NO -S? ulendichte. Eine sehr gute ? bereinstimmung zwischen2
den Messungen des AMAXDOAS Instruments und denen von SCIAMACHY kann erzielt
werden, wenn die lokalen atmosph? rischen Bedingungen ber? cksichtigt werden. Eine lineare
Regression der Datens? tze ergab eine Steigung von 1 – 0.07.
Das AMAXDOAS Instrument eignet sich sehr gut zur Bestimmung von Fl? ssen. Eine
Fallstudie f? r einen Flug in der Grenzschicht ergab f? r Milano eine HCHO Produktion von
243.5*10 Molek? le/s. Die Abluftfahne der Stadt war ungef? hr 20 km breit.
Die NO -Konzentrationsverteilung in der Abgasfahne eines Kraftwerks konnte mittels der2
unterschiedlichen S? ulendichten entlang unterschiedlicher Lichtwege rekonstruiert werden.
24Der NO -Fluss am Ort der Messung wurde zu 2.5*10 Molek? le/s abgesch? tzt.2Table of contents
1 Introduction .............................................................................................. 1
2 Tropospheric Chemistry 3
2.1 Nitrogen Oxides and Ozone ............................................................................................ 3
2.2 Hydroxyl Radical and Carbon Oxides ............................................................................ 5
2.3 Formaldehyde and VOCs................................................................................................ 6
3 Differential Optical Absorption Spectroscopy ............................................ 9
3.1 Applications .............................................................................................................. 9
3.2 The Measurement Principle ............................................................................................ 9
3.2.I The DOAS Method............................................................................................ 11
3.2.I.a Measurement and Data Retrieval ................................................................. 13
3.2.I.b The Analysis Procedure ............................................................................... 15
3.2.I.c Residual Structure and Measurement Error ................................................. 15
3.2.II Instrumental Effects........................................................................................... 17
3.2.II.a I -Effect............................................................................................... 180
3.2.II.b Saturation............................................................................................ 19
3.2.III Passive DOAS Systems ..................................................................................... 19
3.2.III.a Reference Spectrum ? Differential Columns...................................... 20
3.2.III.b Ring Effect.......................................................................................... 20
3.3 Spectral Analysis........................................................................................................... 21
3.4 Separation of Tropospheric and Stratospheric Signals ................................................. 24
3.5 DOAS Tomography ...................................................................................................... 26
3.5.I Principle of DOAS Tomography ....................................................................... 26
3.5.II Mathematical Inversion Techniques.................................................................. 28
3.5.III Sensitivity Studies.............................................................................................. 29
4 Radiative transfer.........................................................................................33
4.1 Slant and vertical columns ............................................................................................ 33
4.2 Scattering Processes and Extinction.............................................................................. 36
4.2.I Surface Reflection.............................................................................................. 36
4.2.II Rayleigh Scattering............................................................................................ 37
4.2.III Raman Scattering............................................................................................... 38
4.2.IV Aerosol Scattering.............................................................................................. 38
4.2.IV.a Absorption .......................................................................................... 40
4.2.IV.b Total Extinction .................................................................................. 41
4.3 Radiative Transfer Modelling ....................................................................................... 42
4.4 Sensitivity Studies......................................................................................................... 43
4.4.I Flight Altitude Studies ....................................................................................... 44
4.4.II Influence of Clouds on tropospheric NO -AMF................................................ 452
4.4.III Mixing Layer Height ......................................................................................... 46
4.4.IV Solar Azimuth Dependency ............................................................................... 47
4.4.V Aerosol Extinction ............................................................................................. 48
4.4.VI Terrain Level...................................................................................................... 49
4.4.VII Two-dimensional Box AMFs....................................................................... 50
4.4.VII.a Single Scattering Approximation ....................................................... 53
4.4.VII.b Comparison between single and multi scattering approximation....... 56
4.5 Applications ............................................................................................................ 57
4.5.I Langley Plot....................................................................................................... 58
I4.5.II Light Path Enhancement inside a large Cloud.........................................................59
4.5.II.a Measurement Results....................................................................................60
4.5.II.b Retrieval of Light path enhancements ..........................................................61
4.5.III Retrieval of a varying Aeros