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| Titel |
Measurements and modelling of I2, IO, OIO, BrO and NO3 in the mid-latitude marine boundary layer |
| VerfasserIn |
A. Saiz-Lopez, J. A. Shillito, H. Coe, J. M. C. Plane |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 6, no. 6 ; Nr. 6, no. 6 (2006-05-11), S.1513-1528 |
| Datensatznummer |
250003820
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| Publikation (Nr.) |
 copernicus.org/acp-6-1513-2006.pdf |
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| Zusammenfassung |
| Time series observations of molecular iodine (I2), iodine
oxides (IO, OIO), bromine oxide (BrO), and the nitrate radical
(NO3) in the mid-latitude coastal marine boundary layer
(MBL) are reported. Measurements were made using a new long-path
DOAS instrument during a summertime campaign at Mace Head on the
B3Π(0+u)-X1Σ+g electronic transition
between 535 and 575 nm. The I2 mixing ratio was found to
vary from below the detection limit (~5 ppt) up to a nighttime
maximum of 93 ppt. Along with I2, observations of IO, OIO
and NO3 were also made during the night. Surprisingly, IO
and OIO were detected at mixing ratios up to 2.5 and 10.8 ppt,
respectively. A model is employed to show that the reaction
between I2 and NO3 is the likely nighttime source of
these radicals. The BrO mixing ratio varied from below the
detection limit at night (~1 ppt) to a maximum of 6 ppt in the
first hours after sunrise. A bromine chemistry model is used to
simulate the diurnal behaviour of the BrO radical, demonstrating the
importance of halogen recycling through sea-salt aerosol. In the
same campaign a zenith sky DOAS was employed to determine the column
density variation of NO3 as a function of solar zenith angle
(SZA) during sunrise, from which vertical profiles of NO3
through the troposphere were obtained. On several occasions a
positive gradient of NO3 was observed over the first 2 km,
possibly due to dimethyl sulphide (DMS) removing NO3 at the
ocean surface. |
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