Investigation of the stratospheric inorganic Bromine budget for 1996 - 2000 : balloon-borne measurements and model comparisons

Inorganic bromine plays an important role in catalytic ozone depletion in the stratosphere at high and mid-latitudes. This study reports and discusses in detail stratospheric DOAS (Differential Optical Absorption Spectroscopy) BrO vertical profile measurements with direct sunlight, that were conducted aboard the french-german LPMA/DOAS (Laboratoire de Physique Moléculaire et Application) balloon gondola at mid and high northern latitudes during the years 1996 to 2000. The unprecedented high accuracy (+/-12) of the BrO measurements together with 3-D CTM and Lagrangian photochemical modelling provided new insights into the budget and chemistry of atmospheric bromine. These include (1) a thorough investigation of the present and recent budget of stratospheric bromine, (2) an improved understanding of the chemistry of stratospheric bromine, and (3) the first measurements of free tropospheric $BrO$ concentration profiles. The total inorganic bromine (in 5.6 year old air in 1999) determined from BrO measurements (21.5+/-3) ppt) was tested for the first time against the total stratospheric bromine inferred from the organic bromine method (18.4+/-1.8) ppt. The agreement of total bromine found with both methods is good, however, the consistently larger inorganic bromine suggests an influx (3.1+/-3.5 ppt) of inorganic bromine from the troposphere. This conclusion is supported by finding (3) and qualitatively by the recent detection of inorganic bromine at a 1 ppt level in the upper tropospheric aerosol. Thus this thesis could establish a more complete budget of stratospheric bromine. Also, a new DOAS retrieval algorithm was developed for the detection of chlorine dioxide (OClO) in the balloon-borne direct sun spectra. In all Arctic winter flights OClO could be detected - even at low chlorine activation. Surprisingly, OClO could also be measured in significant amounts (5-10 ppt at 20-30 km and a solar zenith angle (SZA) of 88-93°) during a fall

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2000

Author dc:creator

• Fitzenberger, Richard

Contributors dc:contributor

• Platt, Ulrich

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/1407

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:1407