The vertical distribution of atmospheric BrO from ground-based measurements
Ground-based UV-Visible measurements targeting BrO were made at Lauder, New Zealand (45.0°S, 169.7°E) and Arrival Heights, Antarctica (77.8°S, 166.7°E). Differential Optical Absorption Spectroscopy (DOAS) was used to determine differential slant column densities (DSCDs) from the radiance measurement...
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ftunivauckland:oai:researchspace.auckland.ac.nz:2292/357 2023-05-15T13:53:19+02:00 The vertical distribution of atmospheric BrO from ground-based measurements Schofield, Robyn Karin Kreher Brian Connor David Shooter 2003 Scanned from print thesis http://hdl.handle.net/2292/357 en eng ResearchSpace@Auckland PhD Thesis - University of Auckland UoA1202695 Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm Copyright: The author Thesis 2003 ftunivauckland 2013-12-07T08:28:41Z Ground-based UV-Visible measurements targeting BrO were made at Lauder, New Zealand (45.0°S, 169.7°E) and Arrival Heights, Antarctica (77.8°S, 166.7°E). Differential Optical Absorption Spectroscopy (DOAS) was used to determine differential slant column densities (DSCDs) from the radiance measurements. UV-Visible measurements have been made in the two complementary viewing geometries of direct-sun and zenith-sky. A spherical curved earth single scattering radiative transfer model was developed. The effects of refraction, molecular absorption, Rayleigh and Mie scattering were included. Singularity at the tangent point was avoided and a complete intensity calculation performed. The DSCDs for both the direct-sun and zenith-sky viewing measurements were calculated with this forward model. A general optimal estimation retrieval algorithm was developed to retrieve altitude information by combining DSCDs from the direct-sun and zenith-sky viewing geometries. A complete retrieval characterisation and error analysis was performed. The characterisation illustrated that tropospheric sensitivity was obtained from the direct-sun viewing measurements, while the zenith-sky measurements were essential for stratospheric sensitivity. Stratospheric and tropospheric BrO columns were retrieved for the diurnal stages of 80°, 84° and 87° SZA for Lauder. The diurnal and seasonal variation of the stratospheric column was successfully retrieved from the measurements. The stratospheric columns were consistent with a stratospheric Bry loading of 20 ppt. The tropospheric BrO column retrieved over Lauder was less than 0.9 ppt if a uniform distribution throughout the troposphere is assumed. This is consistent with, though lower than, previous estimates of BrO in the free troposphere of 0.5-2.0 ppt (Richter et al., 2002). The results of a ten week measurement campaign at Arrival Heights for the spring 2002 are presented. Stratospheric and tropospheric BrO columns were retrieved at 80°, 84° and 88° SZA. A high variability was observed for the retrieved stratospheric columns, due in part to the unusual stratospheric warming in the Antarctic spring 2002 (Allen et al., 2003). A mean ubiquitous tropospheric background of 0.3 ppt was retrieved. Also a ‘bromine explosion’ event was observed, corresponding to a BrO mixing ratio of 7 ppt for a uniformly mixed boundary layer. Thesis Antarc* Antarctic Antarctica University of Auckland Research Repository - ResearchSpace Antarctic Arrival Heights ENVELOPE(166.650,166.650,-77.817,-77.817) New Zealand Tangent Point ENVELOPE(-129.947,-129.947,53.560,53.560) The Antarctic |
institution |
Open Polar |
collection |
University of Auckland Research Repository - ResearchSpace |
op_collection_id |
ftunivauckland |
language |
English |
description |
Ground-based UV-Visible measurements targeting BrO were made at Lauder, New Zealand (45.0°S, 169.7°E) and Arrival Heights, Antarctica (77.8°S, 166.7°E). Differential Optical Absorption Spectroscopy (DOAS) was used to determine differential slant column densities (DSCDs) from the radiance measurements. UV-Visible measurements have been made in the two complementary viewing geometries of direct-sun and zenith-sky. A spherical curved earth single scattering radiative transfer model was developed. The effects of refraction, molecular absorption, Rayleigh and Mie scattering were included. Singularity at the tangent point was avoided and a complete intensity calculation performed. The DSCDs for both the direct-sun and zenith-sky viewing measurements were calculated with this forward model. A general optimal estimation retrieval algorithm was developed to retrieve altitude information by combining DSCDs from the direct-sun and zenith-sky viewing geometries. A complete retrieval characterisation and error analysis was performed. The characterisation illustrated that tropospheric sensitivity was obtained from the direct-sun viewing measurements, while the zenith-sky measurements were essential for stratospheric sensitivity. Stratospheric and tropospheric BrO columns were retrieved for the diurnal stages of 80°, 84° and 87° SZA for Lauder. The diurnal and seasonal variation of the stratospheric column was successfully retrieved from the measurements. The stratospheric columns were consistent with a stratospheric Bry loading of 20 ppt. The tropospheric BrO column retrieved over Lauder was less than 0.9 ppt if a uniform distribution throughout the troposphere is assumed. This is consistent with, though lower than, previous estimates of BrO in the free troposphere of 0.5-2.0 ppt (Richter et al., 2002). The results of a ten week measurement campaign at Arrival Heights for the spring 2002 are presented. Stratospheric and tropospheric BrO columns were retrieved at 80°, 84° and 88° SZA. A high variability was observed for the retrieved stratospheric columns, due in part to the unusual stratospheric warming in the Antarctic spring 2002 (Allen et al., 2003). A mean ubiquitous tropospheric background of 0.3 ppt was retrieved. Also a ‘bromine explosion’ event was observed, corresponding to a BrO mixing ratio of 7 ppt for a uniformly mixed boundary layer. |
author2 |
Karin Kreher Brian Connor David Shooter |
format |
Thesis |
author |
Schofield, Robyn |
spellingShingle |
Schofield, Robyn The vertical distribution of atmospheric BrO from ground-based measurements |
author_facet |
Schofield, Robyn |
author_sort |
Schofield, Robyn |
title |
The vertical distribution of atmospheric BrO from ground-based measurements |
title_short |
The vertical distribution of atmospheric BrO from ground-based measurements |
title_full |
The vertical distribution of atmospheric BrO from ground-based measurements |
title_fullStr |
The vertical distribution of atmospheric BrO from ground-based measurements |
title_full_unstemmed |
The vertical distribution of atmospheric BrO from ground-based measurements |
title_sort |
vertical distribution of atmospheric bro from ground-based measurements |
publisher |
ResearchSpace@Auckland |
publishDate |
2003 |
url |
http://hdl.handle.net/2292/357 |
long_lat |
ENVELOPE(166.650,166.650,-77.817,-77.817) ENVELOPE(-129.947,-129.947,53.560,53.560) |
geographic |
Antarctic Arrival Heights New Zealand Tangent Point The Antarctic |
geographic_facet |
Antarctic Arrival Heights New Zealand Tangent Point The Antarctic |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
PhD Thesis - University of Auckland UoA1202695 |
op_rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm Copyright: The author |
_version_ |
1766258365804052480 |