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Airborne DOAS limb measurements of tropospheric trace gas profiles: case study on the profile retrieval of O4 and BrO

Prados-Roman, C. and Butz, A. and Deutschmann, T. and Dorf, M. and Kritten, L. and Minikin, Andreas and Platt, U. and Schlager, Hans and Sihler, H. and Theys, N. and Van Roozendael, M. and Wagner, T. and Pfeilsticker, K. (2011) Airborne DOAS limb measurements of tropospheric trace gas profiles: case study on the profile retrieval of O4 and BrO. Atmospheric Measurement Techniques, 4, pp. 1241-1260. European Geosciences Union. DOI: 10.5194/amt-4-1241-2011.

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Official URL: http://www.atmos-meas-tech.net/4/1241/2011/amt-4-1241-2011.html

Abstract

A novel limb scanning mini-DOAS spectrometer for the detection of UV/vis absorbing radicals (e.g., O3, BrO, IO, HONO) was deployed on the DLR-Falcon (Deutsches Zentrum f�¼r Luft- und Raumfahrt) aircraft and tested during the ASTAR 2007 campaign (Arctic Study of Tropospheric Aerosol, Clouds and Radiation) that took place at Svalbard (78�° N) in spring 2007. Our main objectives during this campaign were to test the instrument, and to perform spectral and profile retrievals of tropospheric trace gases, with particular interest on investigating the distribution of halogen compounds (e.g., BrO) during the so-called ozone depletion events (ODEs). In the present work, a new method for the retrieval of vertical profiles of tropospheric trace gases from tropospheric DOAS limb observations is presented. Major challenges arise from modeling the radiative transfer in an aerosol and cloud particle loaded atmosphere, and from overcoming the lack of a priori knowledge of the targeted trace gas vertical distribution (e.g., unknown tropospheric BrO vertical distribution). Here, those challenges are tackled by a mathematical inversion of tropospheric trace gas profiles using a regularization approach constrained by a retrieved vertical profile of the aerosols extinction coefficient EM. The validity and limitations of the algorithm are tested with in situ measured EM, and with an absorber of known vertical profile (O4). The method is then used for retrieving vertical profiles of tropospheric BrO. Results indicate that, for aircraft ascent/descent observations, the limit for the BrO detection is roughly 1.5 pptv (pmol molâ��1), and the BrO profiles inferred from the boundary layer up to the upper troposphere and lower stratosphere have around 10 degrees of freedom. For the ASTAR 2007 deployments during ODEs, the retrieved BrO vertical profiles consistently indicate high BrO mixing ratios (â�¼15 pptv) within the boundary layer, low BrO mixing ratios (â�¤1.5 pptv) in the free troposphere, occasionally enhanced BrO mixing ratios (â�¼1.5 pptv) in the upper troposphere, and increasing BrO mixing ratios with altitude in the lowermost stratosphere. These findings agree reasonably well with satellite and balloon-borne soundings of total and partial BrO atmospheric column densities.

Document Type:Article
Title:Airborne DOAS limb measurements of tropospheric trace gas profiles: case study on the profile retrieval of O4 and BrO
Authors:
AuthorsInstitution or Email of Authors
Prados-Roman, C.Univ. of Heidelberg
Butz, A.SRON, Utrecht, NL
Deutschmann, T.Univ. of Heidelberg
Dorf, M.Univ. of Heidelberg
Kritten, L.Univ. of Heidelberg
Minikin, AndreasUNSPECIFIED
Platt, U.Univ. of Heidelberg
Schlager, HansUNSPECIFIED
Sihler, H.Univ. of Heidelberg
Theys, N.BIRA-IASB, B
Van Roozendael, M.BIRA-IASB, B
Wagner, T.MPIC, Mainz
Pfeilsticker, K.Univ. of Heidelberg
Date:2011
Journal or Publication Title:Atmospheric Measurement Techniques
Refereed publication:Yes
In Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:4
DOI:10.5194/amt-4-1241-2011
Page Range:pp. 1241-1260
Publisher:European Geosciences Union
Status:Published
Keywords:DOAS, ASTAR, Falcon, tropospheric trace gas profiles, Svalbard
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben Atmosphären- und Klimaforschung
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Trace Species
Deposited By: Dr.rer.nat. Andreas Minikin
Deposited On:07 Dec 2011 14:04
Last Modified:12 Dec 2013 21:27

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