Spectroscopic measurements of tropospheric iodine oxide at Neumayer Station, Antarctica

Frieß, Udo; Wagner, Thomas; Pundt, I.; Pfeilsticker, Klaus; Platt, U.

doi:10.1029/2000gl012784

Cited by 113 publications

(109 citation statements)

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“…The IO SCDs estimated from the MAX-DOAS measurements at Neumayer and from our previous zenith-sky measurements at Neumayer (Frieß et al, 2001) are of the same order of magnitude (around (2 − 10) × 10 13 molec/cm 2 ). In Frieß et al (2001), the seasonal variation of the IO dSCD, i.e.…”

Section: Seasonal Variation Of Iosupporting

confidence: 48%

“…In Frieß et al (2001), the seasonal variation of the IO dSCD, i.e. the difference between SZA=80 • and 92 • was presented, showing a decrease in summer.…”

Section: Seasonal Variation Of Iomentioning

confidence: 99%

“…The Neumayer DOAS instrument has already been described in detail elsewhere (Ferlemann et al, 2000;Frieß et al, 2001Frieß et al, , 2004 and is therefore only briefly described here. It consists of two separate spectrograph-detector units consisting of holographic concave gratings and photodiode arrays cooled to −30 • C to minimise dark current and detector noise.…”

Section: Instrumentalmentioning

confidence: 99%

“…Iodine monoxide (IO) mixing ratios of several ppt have been detected by ground-based passive and active differential optical absorption spectroscopy (DOAS) (Frieß et al, 2001;Saiz-Lopez et al, 2007b). Observations from satellite (Schönhardt et al, 2008;Saiz-Lopez et al, 2007a) indicate that the presence of IO is a widespread phenomenon along the Antarctic coast and over the sea ice covered Antarctic ocean.…”

Section: Introductionmentioning

confidence: 99%

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Iodine monoxide in the Antarctic snowpack

et al. 2010

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Abstract. Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that high IO concentrations in the order of 50 ppb are present in the snow interstitial air. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS). Using a coupled atmosphere -snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations.

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Section: Seasonal Variation Of Iosupporting

confidence: 48%

“…In Frieß et al (2001), the seasonal variation of the IO dSCD, i.e. the difference between SZA=80 • and 92 • was presented, showing a decrease in summer.…”

Section: Seasonal Variation Of Iomentioning

confidence: 99%

Section: Instrumentalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Iodine monoxide in the Antarctic snowpack

et al. 2010

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“…BrCl). The latter are rapidly photolyzed to halogen atoms.In Antarctica, besides BrO up to 20 pmol/mol IO was observed (13,14), which enhances the ozone depletion. Nevertheless, so far no IO has been reliably observed in the Arctic.…”

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confidence: 99%

Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

Pöhler

Vogel

Frieß

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

119

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In the polar tropospheric boundary layer, reactive halogen species (RHS) are responsible for ozone depletion as well as the oxidation of elemental mercury and dimethyl sulphide. After polar sunrise, air masses enriched in reactive bromine cover areas of several million square kilometers. Still, the source and release mechanisms of halogens are not completely understood. We report measurements of halogen oxides performed in the Amundsen Gulf, Arctic, during spring 2008. Active long-path differential optical absorption spectroscopy (LP-DOAS) measurements were set up offshore, several kilometers from the coast, directly on the sea ice, which was never done before. High bromine oxide concentrations were detected frequently during sunlight hours with a characteristic daily cycle showing morning and evening maxima and a minimum at noon. The, so far, highest observed average mixing ratio in the polar boundary layer of 41 pmol/mol (equal to pptv) was detected. Only short sea ice contact is required to release high amounts of bromine. An observed linear decrease of maximum bromine oxide levels with ambient temperature during sunlight, between −24°C and −15°C, provides indications on the conditions required for the emission of RHS. In addition, the data indicate the presence of reactive chlorine in the Arctic boundary layer. In contrast to Antarctica, iodine oxide was not detected above a detection limit of 0.3 pmol/mol.halogen chemistry | ozone depletion | bromine explosion | polar | DOAS T he depletion of the stratospheric ozone layer due to reactive halogen species is well known. Similarly, ozone depletion events (ODEs) in the polar boundary layer, arising after sunrise, were discovered in the 1980s (1, 2, 3). These events were found to be related to high concentrations of filterable bromine. It was therefore proposed that ozone could be destroyed by catalytic reaction cycles involving bromine atoms (Br) and bromine monoxide (BrO) (4).The initial reaction is the release of Br 2 from the liquid to the gas phase and the photolysis to Br, which will lead to a quick oxidation to BrO by destroying an ozone molecule. Note that there is always some production of Br atoms from the photochemical degradation of CH 3 Br, which is ubiquitous in the atmosphere. Bromine atoms are recycled from BrO by different processes. The most important recycling is the BrO self-reaction (R 2·BrO ) with the total rate constant k 2·BrO ¼ 3.2 × 10 −12 cm 3 molec −1 s −1 (5) producing Br atoms or Br 2 . During daylight, Br 2 is again photolyzed to Br, thus all channels of R 2·BrO lead to a net loss of O 3 . Overall, reactive bromine (Br and BrO) acts as a catalyst for ozone destruction. An autocatalytic release of bromine from the sea salt surface ice, the so-called "bromine explosion" (6), supplies sufficient bromine to the gas phase. A simplified overview on bromine release mechanisms and ozone destruction cycles is given in Fig. 1 (for a recent review see 7).The key role of bromine was first confirmed by long-path differential optical absorption ...

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Organic iodine in Antarctic sea ice: A comparison between winter in the Weddell Sea and summer in the Amundsen Sea

et al. 2014

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Recent studies have recognized sea ice as a source of reactive iodine to the Antarctic boundary layer. Volatile iodinated compounds (iodocarbons) are released from sea ice, and they have been suggested to contribute to the formation of iodine oxide (IO), which takes part in tropospheric ozone destruction in the polar spring. We measured iodocarbons (CH 3 I, CH 2 ClI, CH 2 BrI, and CH 2 I 2 ) in sea ice, snow, brine, and air during two expeditions to Antarctica, OSO 10/11 to the Amundsen Sea during austral summer and ANT XXIX/6 to the Weddell Sea in austral winter. These are the first reported measurements of iodocarbons from the Antarctic winter. Iodocarbons were enriched in sea ice in relation to seawater in both summer and winter. During summer, the positive relationship to chlorophyll a biomass indicated a biological origin. We suggest that CH 3 I is formed biotically in sea ice during both summer and winter. For CH 2 ClI, CH 2 BrI, and CH 2 I 2 , an additional abiotic source at the snow/ice interface in winter is suggested. Elevated air concentrations of CH 3 I and CH 2 ClI during winter indicate that they are enriched in lower troposphere and may take part in the formation of IO at polar sunrise.

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Spectroscopic measurements of tropospheric iodine oxide at Neumayer Station, Antarctica

Cited by 113 publications

References 16 publications

Iodine monoxide in the Antarctic snowpack

Iodine monoxide in the Antarctic snowpack

Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

Organic iodine in Antarctic sea ice: A comparison between winter in the Weddell Sea and summer in the Amundsen Sea

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