| 1. |
- Choularton, T. W., et al.
(author)
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The Great Dun Fell Cloud Experiment 1993 : An overview
- 1997
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In: Atmospheric Environment. - 1352-2310. ; 31:16, s. 2393-2405
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Journal article (peer-reviewed)abstract
- The 1993 Ground-based Cloud Experiment on Great Dun Fell used a wide range of measurements of trace gases, aerosol particles and cloud droplets at five sites to study their sources and sinks especially those in cloud. These measurements have been interpreted using a variety of models. The conclusions add to our knowledge of air pollution, acidification of the atmosphere and the ground, eutrophication and climate change. The experiment is designed to use the hill cap cloud as a flow-through reactor, and was conducted in varying levels of pollution typical of much of the rural temperate continental northern hemisphere in spring-time.
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| 2. |
- Bower, K. N., et al.
(author)
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The Great Dun Fell experiment 1995 : An overview
- 1999
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In: Atmospheric Research. - 0169-8095. ; 50:3-4, s. 151-184
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Journal article (peer-reviewed)abstract
- During March and April of 1995 a major international field project was conducted at the UMIST field station site on Great Dun Fell in Cumbria, Northern England. The hill cap cloud which frequently envelopes this site was used as a natural flow through reactor to examine the sensitivity of the cloud microphysics to the aerosol entering the cloud and also to investigate the effects of the cloud in changing the aerosol size distribution, chemical composition and associated optical properties. To investigate these processes, detailed measurements of the cloud water chemistry (including the chemistry of sulphur compounds, organic and inorganic oxidised nitrogen and ammonia), cloud microphysics and properties of the aerosol and trace gas concentrations upwind and downwind of the cap cloud were undertaken. It was found that the cloud droplet number was generally strongly correlated to aerosol number concentration, with up to 2000 activated droplets cm-3 being observed in the most polluted conditions. In such conditions it was inferred that hygroscopic organic compounds were important in the activation process. Often, the size distribution of the aerosol was substantially modified by the cloud processing, largely due to the aqueous phase oxidation of S(IV) to sulphate by hydrogen peroxide, but also through the uptake and fixing of gas phase nitric acid as nitrate, increasing the calculated optical scattering of the aerosol substantially (by up to 24%). New particle formation was also observed in the ultrafine aerosol mode (at about 5 nm) downwind of the cap cloud, particularly in conditions of low total aerosol surface area and in the presence of ammonia and HCl gases. This was seen to occur at night as well as during the day via a mechanism which is not yet understood. The implications of these results for parameterising aerosol growth in Global Climate Models are explored.
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| 3. |
- Gieray, R., et al.
(author)
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Phase partitioning of aerosol constituents in cloud based on single-particle and bulk analysis
- 1997
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In: Atmospheric Environment. - 1352-2310. ; 31:16, s. 2491-2502
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Journal article (peer-reviewed)abstract
- Single-particle analysis, performed by laser microprobe mass spectrometry and bulk analytical techniques were used to study aerosol-cloud interactions within the third field campaign of the EUROTRAC subproject 'ground-based cloud experiments' at the Great Dun Fell, Cumbria, U.K. in spring 1993. The shape of the ridge made it possible for ground-based instrumentation to sample similar parcels of air before, during and after their transit through the cloud. A single jet five-stage minicascade impactor was used for sampling particles of the interstitial aerosol. A second impactor worked in tandem with a counter-flow virtual impactor and collected residues of cloud droplets. Considering marine conditions largest droplets nucleated on sea-salt particles, whereas smaller droplets were formed on sulphate and methane sulphonate containing particles. This clearly indicates chemical inhomogeneities in the droplet phase. Particles, which were disfavoured by droplet formation, often contained the highest amounts of water-insoluble carbonaceous matter. For the submicron size range we found that the carbonaceous matter was always internally mixed with sulphate. The fraction of carbonaceous matter increased with decreasing size. A detectable fraction of particles remained in the cloud interstitial air, although they were in size as well as in composition suitable to form cloud droplets. The findings confirm that nucleation is the most important process affecting phase partitioning in cloud, but that spatial and temporal variations of water vapour supersaturation have also an influence on the observed phase partitioning. Proton induced X-ray emission analysis and light absorption measurements of filter samples showed that the average scavenged fraction was 0.77 for sulphur and 0.57 for soot in clouds formed by continental influenced air and 0.62 and 0.44, respectively, for marine influenced clouds.
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| 4. |
- Swietlicki, Erik, et al.
(author)
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Source identification during the Great Dun Fell Cloud Experiment 1993
- 1997
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In: Atmospheric Environment. - 1352-2310. ; 31:16, s. 2441-2451
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Journal article (peer-reviewed)abstract
- A characterisation of the sources influencing the site for the final field campaign of the EUROTRAC subproject GCE (Ground-based Cloud Experiment) at Great Dun Fell, Cumbria, Great Britain in April-May 1993 is presented. The sources were characterised mainly by means of aerosol filter and cascade impactor data, single particle analysis, gas data, data on aromatic organic compounds, cloud water ionic composition, measurements of aerosol size distributions and hygroscopic properties and various meteorological information. Receptor models applied on the aerosol filter and impactor data sets separately revealed two major source types being a marine sea spray source and a long-range transported anthropogenic pollution source. The results of the receptor models were largely consistent with the other observations used in the source identification. Periods of considerable anthropogenic pollution as well as almost pure marine air masses were clearly identified during the course of the experiment.
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| 5. |
- Enlund, Fredrik, 1968, et al.
(author)
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Psoriasis susceptibility locus in chromosome region 3q21 identified in patients from southwest Sweden
- 1999
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In: Eur J Hum Genet. ; 7:7, s. 783-90
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Journal article (peer-reviewed)abstract
- We have performed a pair-wise linkage study in the search for psoriasis susceptibility regions. A preliminary scan was performed on 20 families. In this set we obtained indications of linkage on chromosome 3q21. This region was further investigated using material from a total of 104 families (set 1B) resulting in a non-parametric linkage (NPL) of 1.77. The material was stratified in families whose parental origin is in southwest Sweden (set 1C). A maximum NPL value of 2.77 was obtained in this group. A transmission disequilibrium test (TDT) was performed on the stratified material (set 1C) and a significant P value of 0.005 was obtained, at marker D3S1269. The locus was confirmed with TDT in replicate material consisting of 148 families in which a single member was affected (P value 0.0007) at marker D3S1551. Thus, we have observed a significant P value using TDT in the vicinity of markers D3S1269/D3S1551, suggesting a novel psoriasis susceptibility region.
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