The spatial distribution of the reactive iodine species IO from simultaneous active and passive DOAS observations

We present investigations of the reactive iodine species (RIS) IO, OIO and I<sub>2</sub> in a coastal region from a field campaign simultaneously employing active long path differential optical absorption spectroscopy (LP-DOAS) as well as passive multi-axis differential optical absorption spectroscopy (MAX-DOAS). The campaign took place at the Martin Ryan Institute (MRI) in Carna, County Galway at the Irish West Coast about 6 km south-east of the atmospheric research station Mace Head in summer 2007. In order to study the horizontal distribution of the trace gases of interest, we established two almost parallel active LP-DOAS light paths, the shorter of 1034 m length just crossing the intertidal area, whereas the longer one of 3946 m length also crossed open water during periods of low tide. In addition we operated two passive Mini-MAX-DOAS instruments with the same viewing direction. While neither OIO nor I<sub>2</sub> could be unambiguously identified with any of the instruments, IO could be detected with active as well as passive DOAS. The IO column densities seen at both active LP-DOAS light paths are almost the same. Thus it can be concluded that coastal IO is almost exclusively located in the intertidal area, where we detected mixing ratios of up to 35±7.7 ppt (equivalent to pmol/mol). Nucleation events with particle concentrations of 10<sup>6</sup> cm<sup>−3</sup> particles were observed each day correlating with high IO mixing ratios. Therefore we feel that our detected IO concentrations confirm the results of model studies, which state that in order to explain such particle bursts, IO mixing ratios of 50 to 100 ppt in so called "hot-spots" are required

Iodine monoxide at a clean marine coastal site: observations of high frequency variations and inhomogeneous distributions

The first in situ point observations of iodine monoxide (IO) at a clean marine site were made using a laser-induced fluorescence instrument deployed at Mace Head, Ireland in August 2007. IO mixing ratios of up to 49.8 pptv (equivalent to pmol mol<sup>−1</sup>; 1 s average) were observed at day-time low tide, well in excess of previous observed spatially-averaged maxima. A strong anti-correlation of IO mixing ratios with tide height was evident and the high time resolution of the observations showed IO peaked in the hour after low tide. The temporal delay in peak IO compared to low tide has not been observed previously but coincides with the time of peak aerosol number previously observed at Mace Head. <br><br> A long path-differential optical absorption spectroscopy instrument (with a 2 × 6.8 km folded path across Roundstone Bay) was also based at the site for 3 days during the point measurement observation period. Both instruments show similar temporal trends but the point measurements of IO are a factor of ~6–10 times greater than the spatially averaged IO mixing ratios, providing direct empirical evidence of the presence of inhomogeneities in the IO mixing ratio near the intertidal region

Prevalences of primary headache symptoms at school-entry: a population-based epidemiological survey of preschool children in Germany

Primary headache and functional abdominal pain prevalences in an unselected populationbased sample of German preschool children and their parents (n=885) were collected in relation to health-related quality of life and sociodemographic variables. The pain symptoms were assessed according to IHS classification (2004) and Rome-II criteria (1999) during the 2004 data census. The participation rate was 62.7%, with an equal gender distribution. The focus of this paper lies on the symptom-oriented point prevalences for primary headaches of preschool children: 3.6% headache, 33.2% abdominal pain, 48.8% headache+abdominal pain and 14.4% without pain. High comorbidities for pain-affected children have been found. Pain intensities differ significantly only for abdominal pain (one-way ANOVA F=3,339, df=4/445, p=0.010*), not for headaches. However, recurrent headaches show a striking ratio in favour of boys (10:1). Children at preschool age have high quality-of-life measures, already influenced negatively by paediatric pain experiences (one-way ANOVA: F=9,193, df=4/546, p=0.000**). Headache and abdominal pain are relevant for children’s everyday life; hence, simultaneous and prospective assessment is an essential issue in public health research

Observations of bromine monoxide transport in the Arctic sustained on aerosol particles

The return of sunlight in the polar spring leads to the production of reactive halogen species from the surface snowpack, significantly altering the chemical composition of the Arctic near-surface atmosphere and the fate of long-range transported pollutants, including mercury. Recent work has shown the initial production of reactive bromine at the Arctic surface snowpack; however, we have limited knowledge of the vertical extent of this chemistry, as well as the lifetime and possible transport of reactive bromine aloft. Here, we present bromine monoxide (BrO) and aerosol particle measurements obtained during the March 2012 BRomine Ozone Mercury EXperiment (BROMEX) near Utqiaġvik (Barrow), AK. The airborne differential optical absorption spectroscopy (DOAS) measurements provided an unprecedented level of spatial resolution, over 2 orders of magnitude greater than satellite observations and with vertical resolution unable to be achieved by satellite methods, for BrO in the Arctic. This novel method provided quantitative identification of a BrO plume, between 500 m and 1 km aloft, moving at the speed of the air mass. Concurrent aerosol particle measurements suggest that this lofted reactive bromine plume was transported and maintained at elevated levels through heterogeneous reactions on colocated supermicron aerosol particles, independent of surface snowpack bromine chemistry. This chemical transport mechanism explains the large spatial extents often observed for reactive bromine chemistry, which impacts atmospheric composition and pollutant fate across the Arctic region, beyond areas of initial snowpack halogen production. The possibility of BrO enhancements disconnected from the surface potentially contributes to sustaining BrO in the free troposphere and must also be considered in the interpretation of satellite BrO column observations, particularly in the context of the rapidly changing Arctic sea ice and snowpack

BrO measurements over the Eastern North-Atlantic

The aim of the work presented here was to detect BrO in the marine boundary layer over the Eastern North-Atlantic by Multi AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS) of scattered sunlight. With this technique, information about the concentration and the vertical profile of trace gases in the atmosphere can be gained. BrO can be formed in the marine atmosphere by degradation of biogenic organohalogens or by oxidation of bromide in sea salt aerosol. BrO influences the chemistry in marine air in many ways, e.g. since it catalytically destroys ozone, changes the NO<sub>2</sub>/NO-ratio as well as the OH/HO<sub>2</sub>-ratio and oxidises DMS. However, the abundance and the significance of BrO in the marine atmosphere is not yet fully understood. <br><br> We report on data collected during a ship cruise, which took place along the West African Coast in February 2007, within the framework of the Surface Ocean PRocesses in the ANthropocene project (SOPRAN). Tropospheric BrO could be detected during this cruise at peak mixing ratios of (10.2±3.7) ppt at an assumed layer height of 1 km on 18 February 2007. Furthermore, it was found that the mean BrO concentrations increased when cruising close to the African Coast suggesting that at least part of the BrO might have originated from there

NO₂ measurements in Hong Kong using LED based long path differential optical absorption spectroscopy

In this study we present the first long term measurements of atmospheric nitrogen dioxide (NO2) using a LED based Long Path Differential Optical Absorption Spectroscopy (LP-DOAS) instrument. This instrument is measuring continuously in Hong Kong since December 2009, first in a setup with a 550 m absorption path and then with a 3820 m path at about 30 m to 50 m above street level. The instrument is using a high power blue light LED with peak intensity at 450 nm coupled into the telescope using a Y-fibre bundle. The LP-DOAS instrument measures NO2 levels in the Kowloon Tong and Mongkok district of Hong Kong and we compare the measurement results to mixing ratios reported by monitoring stations operated by the Hong Kong Environmental Protection Department in that area. Hourly averages of coinciding measurements are in reasonable agreement (R = 0.74). Furthermore, we used the long-term data set to validate the Ozone Monitoring Instrument (OMI) NO2 data product. Monthly averaged LP-DOAS and OMI measurements correlate well (R = 0.84) when comparing the data for the OMI overpass time. We analyzed weekly patterns in both data sets and found that the LP-DOAS detects a clear weekly cycle with a reduction on weekends during rush hour peaks, whereas OMI is not able to observe this weekly cycle due to its fix overpass time (13:30–14:30 LT – local time)

Tropospheric BrO column densities in the Arctic derived from satellite: retrieval and comparison to ground-based measurements

-During polar spring, halogen radicals like bromine monoxide (BrO) play an important role in the chemistry of tropospheric ozone destruction. Satellite measurements of the BrO distribution have become a particularly useful tool to investigate this probably natural phenomenon, but the separation of stratospheric and tropospheric partial columns of BrO is challenging. In this study, an algorithm was developed to retrieve tropospheric vertical column densities of BrO from data of high-resolution spectroscopic satellite instruments such as the second Global Ozone Monitoring Experiment (GOME-2). Unlike recently published approaches, the presented algorithm is capable of separating the fraction of BrO in the activated troposphere from the total BrO column solely based on remotely measured properties. The presented algorithm furthermore allows to estimate a realistic measurement error of the tropospheric BrO column. The sensitivity of each satellite pixel to BrO in the boundary layer is quantified using the measured UV radiance and the column density of the oxygen collision complex O4. A comparison of the sensitivities with CALIPSO LIDAR observations demonstrates that clouds shielding near-surface trace-gas columns can be reliably detected even over ice and snow. Retrieved tropospheric BrO columns are then compared to ground-based BrO measurements from two Arctic field campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009, respectively. Our algorithm was found to be capable of retrieving enhanced near-surface BrO during both campaigns in good agreement with ground-based data. Some differences between ground-based and satellite measurements observed at Barrow can be explained by both elevated and shallow surface layers of BrO. The observations strongly suggest that surface release processes are the dominating source of BrO and that boundary layer meteorology influences the vertical distribution

The spatial distribution of the reactive iodine species io from simultaneous active and passive doas observations

We present investigations of the reactive iodine species (RIS) IO, OIO and I-2 in a coastal region from a field campaign simultaneously employing active long path differential optical absorption spectroscopy (LP-DOAS) as well as passive multi-axis differential optical absorption spectroscopy (MAX-DOAS). The campaign took place at the Martin Ryan Institute (MRI) in Carna, County Galway at the Irish West Coast about 6 km south-east of the atmospheric research station Mace Head in summer 2007. In order to study the horizontal distribution of the trace gases of interest, we established two almost parallel active LP-DOAS light paths, the shorter of 1034 m length just crossing the intertidal area, whereas the longer one of 3946 m length also crossed open water during periods of low tide. In addition we operated two passive Mini-MAX-DOAS instruments with the same viewing direction. While neither OIO nor I-2 could be unambiguously identified with any of the instruments, IO could be detected with active as well as passive DOAS. The IO column densities seen at both active LP-DOAS light paths are almost the same. Thus it can be concluded that coastal IO is almost exclusively located in the intertidal area, where we detected mixing ratios of up to 29 +/- 8.8 ppt (equivalent to pmol/mol). Nucleation events with particle concentrations of 10(6) cm(-3) particles were observed each day correlating with high IO mixing ratios. Therefore we feel that our detected IO concentrations confirm the results of model studies, which state that in order to explain such particle bursts, IO mixing ratios of 50 to 100 ppt in so called 'hot-spots' are required

The spatial distribution of the reactive iodine species io from simultaneous active and passive doas observations

We present investigations of the reactive iodine species (RIS) IO, OIO and I-2 in a coastal region from a field campaign simultaneously employing active long path differential optical absorption spectroscopy (LP-DOAS) as well as passive multi-axis differential optical absorption spectroscopy (MAX-DOAS). The campaign took place at the Martin Ryan Institute (MRI) in Carna, County Galway at the Irish West Coast about 6 km south-east of the atmospheric research station Mace Head in summer 2007. In order to study the horizontal distribution of the trace gases of interest, we established two almost parallel active LP-DOAS light paths, the shorter of 1034 m length just crossing the intertidal area, whereas the longer one of 3946 m length also crossed open water during periods of low tide. In addition we operated two passive Mini-MAX-DOAS instruments with the same viewing direction. While neither OIO nor I-2 could be unambiguously identified with any of the instruments, IO could be detected with active as well as passive DOAS. The IO column densities seen at both active LP-DOAS light paths are almost the same. Thus it can be concluded that coastal IO is almost exclusively located in the intertidal area, where we detected mixing ratios of up to 29 +/- 8.8 ppt (equivalent to pmol/mol). Nucleation events with particle concentrations of 10(6) cm(-3) particles were observed each day correlating with high IO mixing ratios. Therefore we feel that our detected IO concentrations confirm the results of model studies, which state that in order to explain such particle bursts, IO mixing ratios of 50 to 100 ppt in so called \u27hot-spots\u27 are required