Thesis (M.S.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 62-64). Also available on the World Wide Web.

Thesis (M.Sc.(Chemistry))--University of Pretoria, 2000. / Includes abstract in English and Afrikaans. Includes bibliographical references. Also available online.

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M.Sc. (Instrumental Chemical Analysis) / Please refer to full text to view abstract

No description available.

Airborne measurements of the downward spectral solar irradiance were analyzed with differential optical absorption spectroscopy for the integrated water vapor (IWV) in the atmospheric column above the aircraft. The measurements are obtained from two campaigns in 2016, during which the High Altitude and Long Range Research Aircraft (HALO) took measurements of the downward solar irradiance within the upper troposphere and lower stratosphere (UTLS). The feasibility and limitations of the presented method are discussed for the dry conditions, which are typical for the high altitudes of the UTLS and above. Considering the uncertainties encountered in the irradiance measurements and the high sensitivity of the retrieval, the method was unable to provide sound results for the stratosphere, but provided reasonable results in the troposphere. / Flugzeuggetragene Messungen der abwärtsgerichteten spektralen solaren Irradianz wurden mit der Methode der differenziellen optischen Absorptionsspektroskopie auf den integrierten Wasserdampf (IWV) in der Atmosphäre oberhalb des Flugzeuges untersucht. Im Rahmen zweier Messkampagnen im Jahr 2016 führte das High Altitude and Long Range Research Aircraft (HALO) Messungen der spektralen solaren Irradianz in dem Höhenbereich der oberen Troposphäre und unteren Stratosphäre (UTLS) durch. Hier werden das Potential und die Limitierungen eines solchen Verfahrens untersucht, um Wasserdampf in den trockenen Gegebenheiten abzuleiten, die in und oberhalb der UTLS herrschen. Angesichts der Messunsicherheiten und der hohen Sensitivität des Verfahrens, konnten in der Statosphäre nicht aussagekräftige Ergebnisse erreicht werden, aber in der Troposphäre konnte das Verfahren zuverlässige Ergebnisse liefern.

The main objective was to develop a procedure based on differential optical absorption spectroscopy (DOAS) to measure atmospheric total column of ozone, using the automated instrument developed at the University of North Texas (UNT) by Nebgen in 2006. This project also explored the ability of this instrument to provide measurements of atmospheric total column nitrogen dioxide. The instrument is located on top of UNT’s Environmental Education, Science and Technology Building. It employs a low cost spectrometer coupled with fiber optics, which are aimed at the sun to collect solar radiation. Measurements taken throughout the day with this instrument exhibited a large variability. The DOAS procedure derives total column ozone from the analysis of daily DOAS Langley plots. This plot relates the measured differential column to the airmass factor. The use of such plots is conditioned by the time the concentration of ozone remains constant. Observations of ozone are typically conducted throughout the day. Observations of total column ozone were conducted for 5 months. Values were derived from both DOAS and Nebgen’s procedure and compared to satellite data. Although differences observed from both procedures to satellite data were similar, the variability found in measurements was reduced from 70 Dobson units, with Nebgen’s procedure, to 4 Dobson units, with the DOAS procedure.A methodology to measure atmospheric nitrogen dioxide using DOAS was also investigated. Although a similar approach to ozone measurements could be applied, it was found that such measurements were limited by the amount of solar radiation collected by the instrument. Observations of nitrogen dioxide are typically conducted near sunrise or sunset, when solar radiation experiences most of the atmospheric absorption.