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| Titel |
Understanding Hotspots of Iodine Chemistry: Comparison of Spatially-averaged and Point Measurements of Iodine Monoxide |
| VerfasserIn |
R. Commane, C. S. E. Bale, T. Ingham, D. E. Heard, W. J. Bloss, K. Seitz, U. Platt |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024161
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| Zusammenfassung |
| The iodine monoxide (IO) radical plays an important role in marine boundary layer
chemistry. IO catalytically destroys ozone, affects HOx and NOx partitioning and has been
implicated as a precursor to new particle formation. IO is formed by the reaction of ozone
with iodine atoms generated by the photolysis of molecular iodine and photo-labile
iodocarbons.
Measurements of IO were made at the Mace Head Atmospheric Research Station
(MHARS) in August 2007 using two different methods. Point measurements of IO were
made using a portable laser-induced fluorescence (LIF) instrument. The measurement point
was located 50 m from a narrow intertidal region, with macroalgae exposed only at some low
tides. A long-path differential optical absorption spectroscopy (LP-DOAS) instrument
measured IO concentrations over a large spatial scale from the point measurement site (14 km
total path length), including measurements across intertidal regions containing
macro-algae.
High time-resolution (10 s) data from the LIF instrument shows significant variability in
IO mixing ratios at low tide (± 20 pptv over 1 minute). LIF point measurements of IO peaked
at 33.8 pptv (10 s integration time) at daytime low tide (the highest mixing ratios of IO
measured worldwide), while DOAS spatially-averaged measurements of IO peaked at 4.4
pptv (10 minute integration time) over the same period. Data from the two instruments are
compared with tidal variations and the relationship between point and spatially-averaged
measurements is analysed. |
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