Observations of Tropospheric and Stratospheric Bromine Monoxide from Satellite : Analysis of Satellite Data derived from GOME for 1996-2001

• Main Author: Hollwedel, Jens C.
• Format: Doctoral or Postdoctoral Thesis
• Language: German
• Published: 2004
• Subjects: ddc-530; 530 Physics; Sea ice
• Online Access: https://archiv.ub.uni-heidelberg.de/volltextserver/5349/; https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/5349/1/diss_v1.0.pdf; https://doi.org/10.11588/heidok.00005349; https://nbn-resolving.org/urn:nbn:de:bsz:16-opus-53497

Column densities of bromine monoxide have been derived from satellite borne Global Ozone Monitoring Experiment measurements for the time period from 1996 to 2001 on a global scale. This data set has been analyzed under various aspects: two methods two achieve a separation of the stratospheric and tropospheric fractions of the total column density have been developed. The method relying on a fixed solar zenith angle interval has been used to study the evolution of stratospheric BrO abundances. As a result, it has been found in accordance with other measurements that the average stratospheric BrO load has increased during the time period under investigation. Time series of tropospheric column density fractions derived with the other method using a reference site, have been successfully compared to in-situ ozone measurements yielding a reasonably good correlation. Differences between both hemispheres in stratospheric as well as tropospheric BrO have been discussed. The northern hemisphere usually shows higher stratospheric and tropospheric column densities. Sources and source strengths of boundary layer BrO have been investigated. Enhanced tropospheric boundary layer BrO is often released in bromine explosion events during polar spring leading to tropospheric ozone holes. The sea-ice and especially frost flowers are the sources for these events. The area covered by ’clouds’ of enhanced BrO column densities in the northern hemisphere has increased by about 10% per year from 1996 to 2001. This indicates that the source strength has increased which is probably due to changes in the Arctic sea-ice cover. The identification of other sources like volcanoes or salt lakes from this satellite borne instrument has not been successful. Strong evidence for a free tropospheric BrO background has been gathered. It has been estimated that about 2pptv BrO are present in the free troposphere with a lower boundary of its lifetime of about four days. Transport events of polar tropospheric Bro towards mid-latitudes and into the free ...