Observations of reactive bromine, iodine and chlorine species in the Arctic and Antarctic with Differential Optical Absorption Spectroscopy

• Main Author: Zielcke, Johannes
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2015
• Subjects: 530; 530 Physics; Antarc*; Antarctic; Arctic; Ross Island; Weddell Sea
• Online Access: https://archiv.ub.uni-heidelberg.de/volltextserver/18932/; https://archiv.ub.uni-heidelberg.de/volltextserver/18932/1/Dissertation_Johannes_Zielcke_2015_Uni_HD.pdf; https://doi.org/10.11588/heidok.00018932; https://nbn-resolving.org/urn:nbn:de:bsz:16-heidok-189321

A unique feature of the polar troposphere is the strong activity of halogen photochemistry, in which reactive halogen species (RHS), such as BrO, IO and ClO, are responsible for ozone depletion, the oxidation of elemental mercury and dimethyl sulphide. The typical abundances, sources, as well as the release and recycling mechanisms of these halogen species are far from being completely understood. Within this work, field observations were undertaken, in the Arctic (at Alert) and Antarctic (around Ross Island and in the Weddell Sea), using remote sensing and in-situ instruments based on Differential Optical Absorption Spectroscopy (DOAS) techniques such as MAX-DOAS, CE-DOAS and LP-DOAS. Chlorine monoxide was directly detected and quantified (up to 60 pptv, 20 pptv typical) in the Antarctic boundary layer for the first time, with IO and BrO being present simultaneously. The diurnal variation, correlating with insolation, point to the source being the oxidation of surface Cl- by OH or O3. In the Arctic, IO was observed for the first time on a regional scale and throughout the sunlit period during several years (2007 - 2014). The IO mixing ratios between 0 - 0.5 pptv are in agreement with an inorganic, oceanic source and resemble those at both Antarctic sites. The Antarctic IO mixing ratios are significantly lower than previous measurements at similar locations. IO was not detected (<1 pptv) originating from the snowpack nor within a penguin colony.