English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

During the Arctic Tropospheric OzoneChemistry (ARCTOC) campaigns at Ny-Ålesund, Spitsbergen, the role of halogensin the depletion of boundary layer ozone was investigated. In spring 1995 and1996 up to 30 ppt bromine monoxide were found whenever ozone decreased fromnormal levels of about 40 ppb. Those main trace gases and others werespecifically followed in the UV-VIS spectral region by differential opticalabsorption spectroscopy (DOAS) along light paths running between 20 and 475 ma.s.l.. The daily variation of peroxy radicals closely followed the ozonephotolysis rate J(O3(O1D)) in the absence of ozonedepletion most of the time. However, during low ozone events this closecorrelation was no longer found because the measurement of radicals by chemicalamplification (CA) turned out to be sensitive to peroxy radicals and ClOx.Large CA signals at night can sometimes definitely be assigned to ClOxand reached up to 2 ppt. Total bromine and iodine were both strippedquantitatively from air by active charcoal traps and measured after neutronactivation of the samples. Total bromine increased from background levels ofabout 15 ppt to a maximum of 90 ppt during an event of complete ozone depletion.For the spring season a strong source of bromine is identified in the pack iceregion according to back trajectories. Though biogenic emission sources cannotbe completely ruled out, a primary activation of halogenides by various oxidantsseems to initiate an efficient autocatalytic process, mainly driven by ozone andlight, on ice and perhaps on aerosols. Halogenides residing on pack ice surfacesare continuously oxidised by hypohalogenous acids releasing bromine and chlorineinto the air. During transport and especially above open water this air mixeswith upper layer pristine air. As large quantities of bromine, often in the formof BrO, have been observed at polar sunrise also around Antarctica, its releaseseems to be a natural phenomenon. The source strength of bromine from halogenactivation on the pack ice, as based on the measured inorganic bromine levels,averages about 1012 Br-atoms m-2 s-1 duringsunlit periods in Arctic spring. The total source strength of inorganic brominefrom sunlit polar regions may therefore amount to 30 kt y-1. Key words. Atmospheric composition and structure(troposphere · composition and chemistry; instruments and techniques

The role of bromine and chlorine chemistry for arctic ozone depletion events in Ny-Ålesund and comparison with model calculations