Ground‐based measurements of tropospheric and stratospheric BrO at Arrival Heights, Antarctica

Kreher, K.; Johnston, P. V.; Wood, S.; Nardi, Bruno; Platt, U.

doi:10.1029/97gl02997

Cited by 150 publications

(119 citation statements)

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“…Simultaneous observations by ground-based zenith sky DOAS con®rmed the existence of tropospheric BrO (Wittrock et al, 1996). Similar observations by the same method were reported from Sùndre Strùmfjord, Greenland (Miller et al, 1997), and from Arrival Heights, 77X8 S, 166X7 E, Antarctica (Kreher et al, 1997;Kreher, 1996). Ozone reacts quickly with halogen atoms see Eq.…”

Section: Introductionsupporting

confidence: 74%

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

1999

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Abstract. During the Arctic Tropospheric Ozone Chemistry (ARCTOC) campaigns at Ny-A Ê lesund, Spitsbergen, the role of halogens in the depletion of boundary layer ozone was investigated. In spring 1995 and 1996 up to 30 ppt bromine monoxide were found whenever ozone decreased from normal levels of about 40 ppb. Those main trace gases and others were speci®cally followed in the UV-VIS spectral region by dierential optical absorption spectroscopy (DOAS) along light paths running between 20 and 475 m a.s.l.. The daily variation of peroxy radicals closely followed the ozone photolysis rate J(O 3 (O 1 D)) in the absence of ozone depletion most of the time. However, during low ozone events this close correlation was no longer found because the measurement of radicals by chemical ampli®cation (CA) turned out to be sensitive to peroxy radicals and ClO x . Large CA signals at night can sometimes de®nitely be assigned to ClO x and reached up to 2 ppt. Total bromine and iodine were both stripped quantitatively from air by active charcoal traps and measured after neutron activation of the samples. Total bromine increased from background levels of about 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 identi®ed in the pack ice region according to back trajectories. Though biogenic emission sources cannot be completely ruled out, a primary activation of halogenides by various oxidants seems to initiate an ecient autocatalytic process, mainly driven by ozone and light, on ice and perhaps on aerosols. Halogenides residing on pack ice surfaces are continuously oxidised by hypohalogenous acids releasing bromine and chlorine into the air. During transport and especially above open water this air mixes with upper layer pristine air. As large quantities of bromine, often in the form of BrO, have been observed at polar sunrise also around Antarctica, its release seems to be a natural phenomenon. The source strength of bromine from halogen activation on the pack ice, as based on the measured inorganic bromine levels, averages about 1012 Br-atoms m À2 s À1 during sunlit periods in Arctic spring. The total source strength of inorganic bromine from sunlit polar regions may therefore amount to 30 kt y À1 .

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Section: Introductionsupporting

confidence: 74%

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

1999

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“…Barrie et al, 1988), and has now been observed in the Antarctic (Kreher et al, 1997), where the sparse location Correspondence to: H. K. Roscoe (h.roscoe@bas.ac.uk) of measurement sites means that the ozone-poor air is often lifted above the boundary layer by the time it arrives at the site (Wessel et al, 1998;Roscoe et al, 2001). At first there was some speculation that the Arctic ozone loss might be anthropogenic in origin, but it is now known to be a natural process catalysed by bromine compounds.…”

Section: Introductionmentioning

confidence: 75%

Polar tropospheric ozone depletion events observed in the International Geophysical Year of 1958

Roscoe

Roscoe²

2006

Atmos. Chem. Phys.

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Abstract. The Royal Society expedition to Antarctica established a base at Halley Bay, in support of the International Geophysical Year of 1957–1958. Surface ozone was measured during 1958 only, using a prototype Brewer-Mast sonde. The envelope of maximum ozone was an annual cycle from 10 ppbv in January to 22 ppbv in August. These values are 35% less at the start of the year and 15% less at the end than modern values from Neumayer, also a coastal site. This may reflect a general increase in surface ozone since 1958 and differences in summer at the less windy site of Halley, or it may reflect ozone loss on the inlet together with long-term conditioning. There were short periods in September when ozone values decreased rapidly to near-zero, and some in August when ozone values were rapidly halved. Such ozone-loss episodes, catalysed by bromine compounds, became well-known in the Artic in the 1980s, and were observed more recently in the Antarctic. In 1958, very small ozone values were recorded for a week in midwinter during clear weather with light winds. The absence of similar midwinter reductions at Neumayer, or at Halley in the few measurements during 1987, means we must remain suspicious of these small values, but we can find no obvious reason to discount them. The dark reaction of ozone and seawater ice observed in the laboratory may be fast enough to explain them if the salinity and surface area of the ice is sufficiently amplified by frost flowers.

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“…In situ measurements of BrO in the Antarctic are more limited and have been generally of a short-term nature however are also significant in their findings. Kreher et al (1997) used a zenith sky DOAS instrument to identify sudden large BrO column enhancement during spring 1995 and during four successive austral springs (1999)(2000)(2001)(2002) at Neumeyer. Friess et al (2004Friess et al ( , 2005) used a similar instrument to find that BrO was present in almost all air masses which had previously been in contact with sea-ice surfaces.…”

Section: Introductionmentioning

confidence: 99%

DMS and MSA measurements in the Antarctic Boundary Layer: impact of BrO on MSA production

et al. 2008

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Abstract. In situ measurements of dimethyl sulphide (DMS) and methane sulphonic acid (MSA) with a minimum in sea extent. Whilst seasonal variability and interannual variability can be attributed to a number of factors, short term variability appeared strongly dependent on air mass origin and trajectory pressure height. The MSA and derived non-sea salt sulphate (nss-SO 2− 4 ) measurements showed no correlation with those of DMS (regression R 2 =0.039, and R 2 =0.001 respectively) in-line with the complexity of DMS fluxes, alternative oxidation routes, transport of air masses and variable spatial coverage of both sea-ice and phytoplankton. MSA was generally low throughout the year, with an annual average of 42 ng m −3 (9.8±13.2 pptV), however MSA: nss-SO 2− 4 ratios were high implying a dominance of the addition oxidation route for DMS. Including BrO measurements into MSA production calculations demonstrated the significance of BrO on DMS oxidation within this region of the atmosphere in austral summer. Assuming an 80% yield of DMSO from the reaction of DMS+BrO, an atmospheric concentration of BrO equal to 3 pptV increased the calculated MSA production from DMS by a factor of 9 above that obtained when considering only Correspondence to: K. A. Read (km519@york.ac.uk) reaction with the hydroxyl radical. These findings have significant atmospheric implications, but may also impact on the interpretation of ice cores which previously relied on the understanding of MSA and nss-SO 2− 4 chemistry to provide information on environmental conditions such as sea ice extent and the origins of sulphur within the ice.

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Ground‐based measurements of tropospheric and stratospheric BrO at Arrival Heights, Antarctica

Abstract: Abstract.Ground-based measurements of BrO slant column densities (SCDs) were performed using zenith sky DOAS (Differential Optical Absorption Spectroscopy) during autumn (February'to May) and spring (August to October) of 1995 at Arrival Heights (77.8øS, 166.7øE).In

Cited by 150 publications

References 16 publications

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

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

Polar tropospheric ozone depletion events observed in the International Geophysical Year of 1958

DMS and MSA measurements in the Antarctic Boundary Layer: impact of BrO on MSA production

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