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Journal Publications

This section contains all refereed journal publications that have some connection either with the Mace Head Research Station or with members, both present and past, of the Atmospheric Physics Research Cluster at NUI, Galway.

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Documents

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The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002 The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 9.65 MB

Heard, D. E., K. A. Read, J. Methven, S. Al-Haider, W. J. Bloss, G. P. Johnson, M. J. Pilling, P. W. Seakins, S. C. Smith, R. Sommariva, J. C. Stanton, T. J. Still, B. Brooks, G. De Leeuw, A. V. Jackson, J. B. McQuaid, R. Morgan, M. H. Smith, L. J. Carpenter, N. Carslaw, J. R. Hamilton, J. Hopkins, J. D. Lee, A. C. Lewis, R. M. Purvis, D. J. Wevill, N. Brough, T. Green, G. Mills, S. A. Penkett, J. M. C. Plane, A. Saiz-Lopez, D. Worton, P. S. Monks, Z. Fleming, A. R. Rickard, M. Alfarra, J. D. Allan, K. Bower, H. Coe, M. Cubison, M. Flynn, G. McFiggans, M. Gallagher, E. G. Norton, C. D. O'Dowd, J. Shillito, D. Topping, G. Vaughan, P. Williams, M. Bitter, S. M. Ball, R. L. Jones, I. M. Povey, S. O'Doherty, P. G. Simmonds, A. Allen, R. P. Kinnersley, D. C. S. Beddows, M. Dall'Osto, R. M. Harrison, R. J. Donovan, M. R. Heal, S. G. Jennings, C. Noone and G. Spain, The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002, Atmospheric Chemistry and Physics Discussions, Vol. 5, pp 12177-12254, 2005.


Abstract


The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NOx originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O3, CO, H2, DMS, CH4, NMHC, NOx, NOy, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I2, OIO, IO, BrO), NO3 radicals, photolysis frequencies, the free radicals OH, HO2 and (HO2+Σ RO2), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology for the duration of the campaign is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.

The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002 The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 9.65 MB

Heard, D. E., K. A. Read, J. Methven, S. Al-Haider, W. J. Bloss, G. P. Johnson, M. J. Pilling, P. W. Seakins, S. C. Smith, R. Sommariva, J. C. Stanton, T. J. Still, B. Brooks, G. De Leeuw, A. V. Jackson, J. B. McQuaid, R. Morgan, M. H. Smith, L. J. Carpenter, N. Carslaw, J. R. Hamilton, J. Hopkins, J. D. Lee, A. C. Lewis, R. M. Purvis, D. J. Wevill, N. Brough, T. Green, G. Mills, S. A. Penkett, J. M. C. Plane, A. Saiz-Lopez, D. Worton, P. S. Monks, Z. Fleming, A. R. Rickard, M. Alfarra, J. D. Allan, K. Bower, H. Coe, M. Cubison, M. Flynn, G. McFiggans, M. Gallagher, E. G. Norton, C. D. O'Dowd, J. Shillito, D. Topping, G. Vaughan, P. Williams, M. Bitter, S. M. Ball, R. L. Jones, I. M. Povey, S. O'Doherty, P. G. Simmonds, A. Allen, R. P. Kinnersley, D. C. S. Beddows, M. Dall'Osto, R. M. Harrison, R. J. Donovan, M. R. Heal, S. G. Jennings, C. Noone and G. Spain, The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002, Atmospheric Chemistry and Physics Discussions, Vol. 5, pp 12177-12254, 2005.


Abstract


The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NOx originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O3, CO, H2, DMS, CH4, NMHC, NOx, NOy, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I2, OIO, IO, BrO), NO3 radicals, photolysis frequencies, the free radicals OH, HO2 and (HO2+Σ RO2), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology for the duration of the campaign is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.

The effect of physical and chemical aerosol properties on warm cloud droplet activation The effect of physical and chemical aerosol properties on warm cloud droplet activation

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 1.02 MB

McFiggans, G., P. Artaxo, U. Baltensperger, H. Coe, M. C. Facchini, G. Feingold, S. Fuzzi, M. Gysel,, A. Laaksonen, U. Lohmann, T. F. Mentel, D. M. Murphy, C. D. O'Dowd, J. R. Snider and E. Weingartner, The effect of physical and chemical aerosol properties on warm cloud droplet activation, Atmospheric Chemistry and Physics Discussions, Vol. 5, pp 8507-8647, 2005.


Abstract


The effects of atmospheric aerosol on climate forcing may be very substantial but are quantified poorly at present; in particular, the effects of aerosols on cloud radiative properties, or the "indirect effects" are credited with the greatest range of uncertainty amongst the known causes of radiative forcing. This manuscript explores the effects that the composition and properties of atmospheric aerosol can have on the activation of droplets in warm clouds, so potentially influencing the magnitude of the indirect effect. The effects of size, composition, mixing state and various derived properties are assessed and a range of these properties provided by atmospheric measurements in a variety of locations is briefly reviewed. The suitability of a range of process-level descriptions to capture these aerosol effects is investigated by assessment of their sensitivities to uncertainties in aerosol properties and by their performance in closure studies. The treatment of these effects within global models is reviewed and suggestions for future investigations are made.

Sub-micron sea-spray fluxes Sub-micron sea-spray fluxes

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 134.74 kB
Geever, M., C. O’Dowd, S. van Ekeren, R. Flanagan, D. Nilsson, G. de Leeuw and U. Rannik, Sub-micron sea-spray fluxes. Geophysical Research Letters, Geophys. Res. Lett., 32, L15810, doi:10.1029/2005GL023081, 2005.

Abstract


Eddy covariance aerosol flux measurements were conducted at the Mace Head coastal station in the North East Atlantic. Footprint and micrometeorological analysis under clean marine air mass conditions indicated that fluxes representative of open ocean conditions could be derived during high tide conditions and an oceanic fetch. Sea-spray fluxes were derived for total particle sizes larger than 10 nm and total particle sizes larger than 100 nm (i.e. covering the Aitken and Accumulation mode). The source fluxes (F) were found to be strongly correlated with both wind speed (U) and friction velocity (u*), following, by convention, an exponential relationship (Log F = a U + c) relationship. Comparison of source fluxes at sizes larger than 10 nm and larger than 100 nm demonstrates that approximately 50% of the number flux can be attributed to the accumulation mode and 50% to the Aitken mode. At 10 ms−1 wind speeds, the total primary marine aerosol flux is of the order of 2 × 106 m−2 s−1, increasing to 20 × 106 m−2 s−1 at 20 ms−1.

Quantification of Coastal New Ultra-Fine Particles Formation from In situ and Chamber Measurements during the BIOFLUX Campaign Quantification of Coastal New Ultra-Fine Particles Formation from In situ and Chamber Measurements during the BIOFLUX Campaign

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 1014.54 kB

Sellegri, K., Y. J. Yoon, S. G. Jennings, C. D. O’Dowd, L. Pirjola, S. Cautenet, H. Chen, T. Hoffmann, Quantification of Coastal New Ultra-Fine Particles Formation from In situ and Chamber Measurements during the BIOFLUX Campaign. Environ. Chem. 2, 260. doi:10.1071/EN05074, 2005.


Abstract


Secondary processes leading to the production of ultra-fine particles by nucleation are still poorly understood. A fraction of new particles formed can grow into radiatively active sizes, where they can directly scatter incoming  solar radiation and, if partly water soluble, contribute to the cloud condensation nuclei population. New particle formation events have been frequently observed at the Mace Head Atmospheric Research Station (western Ireland), under low tide and sunny conditions, leading to the hypothesis that new particles are formed from iodo-species emitted from macroalgae.

Performance of a venturi dilution chamber for sampling 3-20 nm particles Performance of a venturi dilution chamber for sampling 3-20 nm particles

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 207.08 kB

Yoon, Y.J., S. Cheevers, S.G. Jennings, C.D. O’Dowd, Performance of a venturi dilution chamber for sampling 3-20 nm particles. J. Aerosol Science, 2005, 36(4), pp 535-540. doi:10.1016/j.jaerosci.2004.10.004


Abstract


The transmission efficiency of a venturi mixing and dilution system was investigated with laboratory generated aerosol by comparison of two condensation particle counters (CPCs). The transmission efficiency exceeded 95% for particle sizes between 3 and 20 nm. The use of the diluter system is demonstrated through comparison with total concentrations derived from a nano-scanning mobility particle sizer (nSMPS) applied to measuring a rapidly changing atmospheric nucleation mode. The study indicates that the diluted-CPC sampler can resolve rapidly changing, and more intense peaks in excess of 106 cm-3, which are otherwise missing or under-sampled by the nSMPS.

Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber

Date added: 08/01/2005
Date modified: 07/23/2009
Filesize: 520.58 kB

Pirjola, L., C. O’Dowd, Y. J. Yoon, K. Sellegri, Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber. Environ. Chem. 2, 271. doi:10.1071/EN05075, 2005.


Abstract


A sectional atmospheric chemistry and aerosol dynamics box model (AEROFOR) was further developed and used to simulate ultra-fine particle formation and growth from seaweed in a chamber flushed with particle-free atmospheric air. In the model, thermodynamically stable clusters were formed by dimer nucleation of OIO vapour, whose precursor was assumed to be molecular I2 emitted by seaweed. Fractal geometry of particles was taken into account. For the I2 fluxes of (0.5–1.5) × 109 cm-3 s-1 the model predicted strong particle bursts, the steady state concentrations of I2 vapour and particles larger than 3 nm were as high as 4 × 109–1.2 × 1010 cm-3 and 5.0 × 106–9.2 × 106 cm-3 respectively. The steady state was reached in less than 150 s and the predicted growth rates of 3–6 nm particles varied in the range of 1.2–3.6 nm min-1. Sensitivity of the size distribution against I2O3 cluster formation, an extra condensable vapour, the photolysis rate of the OIO vapour as well as against the density of (OIO)n-clusters was discussed. The modelled results were in good agreement with the chamber measurements performed during the BIOFLUX campaign in September, 2003, in Mace Head, Ireland, confirming that I2 emissions and nucleation of iodine oxides can largely explain the coastal nucleation phenomenon.

Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber

Date added: 08/01/2005
Date modified: 07/03/2009
Filesize: 520.58 kB

Pirjola, L., C. O’Dowd, Y. J. Yoon, K. Sellegri, Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber. Environ. Chem. 2, 271. doi:10.1071/EN05075, 2005.


Abstract


A sectional atmospheric chemistry and aerosol dynamics box model (AEROFOR) was further developed and used to simulate ultra-fine particle formation and growth from seaweed in a chamber flushed with particle-free atmospheric air. In the model, thermodynamically stable clusters were formed by dimer nucleation of OIO vapour, whose precursor was assumed to be molecular I2 emitted by seaweed. Fractal geometry of particles was taken into account. For the I2 fluxes of (0.5–1.5) × 109 cm-3 s-1 the model predicted strong particle bursts, the steady state concentrations of I2 vapour and particles larger than 3 nm were as high as 4 × 109–1.2 × 1010 cm-3 and 5.0 × 106–9.2 × 106 cm-3 respectively. The steady state was reached in less than 150 s and the predicted growth rates of 3–6 nm particles varied in the range of 1.2–3.6 nm min-1. Sensitivity of the size distribution against I2O3 cluster formation, an extra condensable vapour, the photolysis rate of the OIO vapour as well as against the density of (OIO)n-clusters was discussed. The modelled results were in good agreement with the chamber measurements performed during the BIOFLUX campaign in September, 2003, in Mace Head, Ireland, confirming that I2 emissions and nucleation of iodine oxides can largely explain the coastal nucleation phenomenon.

Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber

Date added: 08/01/2005
Date modified: 07/13/2009
Filesize: 520.58 kB

Pirjola, L., C. O’Dowd, Y. J. Yoon, K. Sellegri, Modelling Iodine Particle Formation and Growth from Seaweed in a Chamber. Environ. Chem. 2, 271. doi:10.1071/EN05075, 2005.


Abstract

 

A sectional atmospheric chemistry and aerosol dynamics box model (AEROFOR) was further developed and used to simulate ultra-fine particle formation and growth from seaweed in a chamber flushed with particle-free atmospheric air. In the model, thermodynamically stable clusters were formed by dimer nucleation of OIO vapour, whose precursor was assumed to be molecular I2 emitted by seaweed. Fractal geometry of particles was taken into account. For the I2 fluxes of (0.5–1.5) × 109 cm-3 s-1 the model predicted strong particle bursts, the steady state concentrations of I2 vapour and particles larger than 3 nm were as high as 4 × 109–1.2 × 1010 cm-3 and 5.0 × 106–9.2 × 106 cm-3 respectively. The steady state was reached in less than 150 s and the predicted growth rates of 3–6 nm particles varied in the range of 1.2–3.6 nm min-1. Sensitivity of the size distribution against I2O3 cluster formation, an extra condensable vapour, the photolysis rate of the OIO vapour as well as against the density of (OIO)n-clusters was discussed. The modelled results were in good agreement with the chamber measurements performed during the BIOFLUX campaign in September, 2003, in Mace Head, Ireland, confirming that I2 emissions and nucleation of iodine oxides can largely explain the coastal nucleation phenomenon.

Measurement of contaminant removal from skin using a portable fluorescence scanning system Measurement of contaminant removal from skin using a portable fluorescence scanning system

Date added: 08/01/2005
Date modified: 07/02/2009
Filesize: 189.8 kB

Hession, H, Byrne, MA, Cleary, S, Andersson, KG and J Roed. Measurement of contaminant removal from skin using a portable fluorescence scanning system. In press: Journal of Environmental Radioactivity, 2005.


Abstract


The residence time of particulate contamination on the human body is a factor that has an important impact on the accuracy of exposure assessment in the aftermath of an accidental release of radionuclides to the atmosphere. Measurements of particle clearance from human skin were made using an illumination system to excite fluorescence in labelled silica particles and a CCD camera and image processing system to detect this fluorescence. The illumination system consists of high-intensity light emitting diodes (LEDS) of suitable wavelengths arranged on a portable stand. The physically small size of the LEDs allows them to be positioned close to the fluorescing surface, thus maximising the fluorescent signal that can be obtained. The limit of detection was found to be 50 μg of tracer particle per cm2.

Experiments were carried out to determine the clearance rates of 10 μm and 3 μm particles from the skin. Results show that, in the absence of any mechanical rubbing of the skin, the clearance of particles from the skin followed an approximately exponential decay with a half-time of 1.5–7.8 h. Skin hairiness and degree of human movement were found, in addition to particle size, to have an important influence on particle fall-off rate.

Marine aerosols and iodine emissions Marine aerosols and iodine emissions

Date added: 08/01/2005
Date modified: 07/24/2009
Filesize: 77.44 kB

O’Dowd, C.D., J.L. Jimenez, R. Bahreini, R.C. Flagan J.H. Seinfeld, L. Pirjola, M. Kulmala, S.FG. Jennings and T. Hoffmann, Marine aerosols and iodine emissions, Nature, DOI 10.1038/nature03373, 2005.


Abstract


The formation of marine aerosols and cloud condensation nuclei—from which marine clouds originate—depends ultimately on the availability of new, nanometre-scale particles in the marine boundary layer. Because marine aerosols and clouds scatter incoming radiation and contribute a cooling effect to the Earth's radiation budget1, new particle production is important in climate regulation. It has been suggested that sulphuric acid—derived from the oxidation of dimethyl sulphide—is responsible for the production of marine aerosols and cloud condensation nuclei. It was accordingly proposed that algae producing dimethyl sulphide play a role in climate regulation2, but this has been difficult to prove and, consequently, the processes controlling marine particle formation remains largely undetermined3, 4. Here, using smog chamber experiments under coastal atmospheric conditions, we demonstrate that new particles can form from condensable iodine-containing vapours, which are the photolysis products of biogenic iodocarbons emitted from marine algae. Moreover, we illustrate, using aerosol formation models, that concentrations of condensable iodine-containing vapours over the open ocean are sufficient to influence marine particle formation. We suggest therefore that marine iodocarbon emissions have a potentially significant effect on global radiative forcing.

Major component composition of urban PM10 and PM2.5 in Ireland Major component composition of urban PM10 and PM2.5 in Ireland

Date added: 08/01/2005
Date modified: 07/02/2009
Filesize: 476.58 kB
Yin, J., A.G. Allen, R.M. Harrison, S.G. Jennings, E. Wright, M. Fitzpatrick, T. Healy, E. Barry, D. Ceburnis and D. McCusker, Major component composition of urban PM10 and PM2.5 in Ireland, Atmospheric Research, Volume 78, Issues 3-4, Pages 149-165. doi:10.1016/j.atmosres.2005.03.006 2005.

Abstract


The major source categories contributing to particulate air pollution in urban as well as non-urban areas of Ireland were studied over an 18-month period using measurements at five sites including urban roadside, urban centre/background, rural and coastal environments. Daily fine and coarse aerosol samples were collected using dichotomous Partisol samplers. The measurements included gravimetric mass (PM10, PM2.5 and PM2.5–10), soluble ions (SO42−, NO3, Cl, CH3SO3, NH4+, Na+, K+, Mg2+ and Ca2+), elemental carbon (EC) and organic carbon (OC). Mass closure procedures using reconstructed chemical components were used to identify major source categories contributing to the aerosol mass, namely primary marine aerosol (NaCl), secondary inorganic materials [NH4NO3 + (NH4)2SO4], primary anthropogenic combustion materials (EC), primary and secondary organic materials, and re-suspended dusts. Source component contributions differed for fine and coarse particles and at different locations. In urban areas, the major components contributing to fine particle mass (together accounting for 79–84% of PM2.5 mass) were, in order, organic compounds, elemental carbon, ammonium sulphate/ammonium nitrate, whilst in the coarse fraction re-suspended material and sea salt were predominant (56–66%). At the rural and coastal sites, PM2.5 mainly consisted of ammonium sulphate/ammonium nitrate and organic materials (65%), whilst sea salt was the largest contributor to coarse particles (39% rural, 56% coastal). Unexplained materials, accounting for about 7–28% of the mass, were attributed mainly to re-suspended materials at urban sites and organic materials at the other sites, as well as unmeasured water content.

Coastal New Particle Formation: A Review of the Current State-Of-The-Art Coastal New Particle Formation: A Review of the Current State-Of-The-Art

Date added: 08/01/2005
Date modified: 07/27/2009
Filesize: 773.65 kB

O’Dowd, C. D., T. Hoffmann, Coastal New Particle Formation: A Review of the Current State-Of-The-Art. Environ. Chem. 2, 245. doi:10.1071/EN05077, 2005.


Abstract


New particle formation via secondary gas-to-particle conversion processes over the oceans is one of the main mechanisms controlling the marine aerosol number population; however, despite extensive effort over the years, this phenomenon is still not well quantified. Coastal new particle formation events are more frequent than open ocean events and consequently have been studied in greater detail. This review article summarizes the recent studies into coastal new particle formation events and summarizes the linkage of these events to iodine emissions and ultimate particle formation via iodine oxide nucleation processes. The current state of knowledge may be summarized by concluding that, in general, coastal nucleation events are driven by biogenic emissions of iodine vapours that undergo rapid chemical reactions to produce condensable iodine oxides leading to nucleation and growth of new particles. The primary source of the condensable iodine vapours is thought to be molecular iodine (I2). The role of iodine oxides in open-ocean new particle production still remains an open question and is the most pressing next step to undertake.

Chemical and physical characteristics of aerosol particles at a remote coastal location, Mace Head, Ireland, during NAMBLEX Chemical and physical characteristics of aerosol particles at a remote coastal location, Mace Head, Ireland, during NAMBLEX

Date added: 08/01/2005
Date modified: 07/01/2009
Filesize: 435.58 kB

Coe, H., J. D. Allan, R. M. Alfarra, K. N. Bower, M. J. Flynn, G. B. McFiggans, D. O. Topping, P. I. Williams, C. D. O'Dowd, M. Dall'Osto, D. C. S. Beddows and R. M. Harrison, Chemical and physical characteristics of aerosol particles at a remote coastal location, Mace Head, Ireland, during NAMBLEX, Atmospheric Chemistry and Physics Discussions, Vol. 5, pp 11643-11678, 2005.


Abstract


Aerosol number concentrations and size distributions from 3 nm to 20 µm diameter were measured at the Mace Head Atmospheric Research Station, Co. Galway, Ireland, a coastal site on the eastern seaboard of the north Atlantic Ocean. Both on and offline size resolved aerosol composition measurements were also made using an Aerodyne Aerosol Mass Spectrometer (AMS) and ion chromatographic analysis of daily samples collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI). Particle number concentrations, size distributions and AMS measurements were determined at 7 and 22 m above ground level to investigate local effects on the aerosol size distribution induced by the tidal zone. During periods of new particle formation ultrafine particle number concentrations are large and variable, however, outside these periods no variability in particle number was observed at any size, nor was the particle composition variable. Analysis of particle size distributions show that within each air mass observed particle number concentrations were very consistent. During anticyclonic periods and conditions of continental outflow Aitken and accumulation mode were enhanced by a factor of 5 compared to the marine sector, whilst coarse mode particles were enhanced during westerly conditions. Baseline marine conditions were rarely met at Mace Head during NAMBLEX and high wind speeds were observed for brief periods only.

Loss rates of gaseous species to aerosol surfaces were calculated for a range of uptake coefficients. Even when the accommodation coefficient is unity, lifetimes of less than 100 s were never observed and rarely were lifetimes less than 500 s. Diffusional limitation to mass transfer is important in most conditions as the coarse mode is always significant, we calculate a minimum overestimate of 50% in the loss rate if this is neglected and so it should always be considered when calculating loss rates of gaseous species to particle surfaces. HO2 and HOI have accommodation coefficients of around 0.03 and hence we calculate lifetimes due to loss to particle surfaces of 2000 s or greater. Aerosol composition measurements using the AMS show accumulation mass modes of acidified sulphate and organic material, both of which have the same shape and are centred at around 350 nm vacuum aerodynamic diameter, implying an internal mixture. The organic and sulphate are approximately equally important, though the mass ratio varies considerably between air masses. Mass spectral fingerprints of the organic fraction in polluted conditions are similar to those observed at other locations that are characterised by aged continental aerosol. Even in marine conditions a background concentration of between 0.5 and 1 µg m−3 of both organic and sulphate was observed. Key differences in the mass spectra were observed during the few clean periods but were insufficient to ascertain whether these changes reflect differences in the source fingerprint of the organic aerosol. However, in an accompanying paper (Dall'Osto et al., 2005) periods of organic dominated aerosol particles were also observed and could be separated from the aged continental aerosol. The coarse mode was composed of sea salt and showed significant displacement of chloride by nitrate and to a lesser extent sulphate in polluted conditions.

Uptake of Methanol to the north Atlantic Ocean Uptake of Methanol to the north Atlantic Ocean

Date added: 08/31/2004
Date modified: 07/27/2009
Filesize: 4.31 kB

Carpenter, L. J., A. C. Lewis, J. R. Hopkins, K. A. Read, I. D. Longley, and M. W. Gallagher (2004), Uptake of methanol to the North Atlantic Ocean surface, Global Biogeochem. Cycles, 18, GB4027, doi:10.1029/2004GB002294.


Abstract

 

Methanol has an almost ubiquitous presence throughout the depth of the troposphere and has been identified as having an important effect on the atmospheric oxidative capacity, yet its global sources and sinks are not well known. Recent evaluations of the methanol budget conclude that a major uncertainty is whether the ocean is a net source or sink. During the North Atlantic Marine Boundary Layer Experiment (NAMBLEX) in July-August 2002, an anticorrelation between methanol concentrations and wind speed and a positive correlation between dimethylsulphide concentrations and wind speed was observed during a 3 day period of cyclonic activity in which the averaged surface wind speed changed substantially as a low pressure system evolved over the northeast Atlantic. The observations agreed well with theoretical predictions derived
assuming air-sea exchange according to the transfer velocity method, embedded in a zero dimensional box model. For the average wind speeds encountered, an irreversible ocean uptake rate of methanol of 8 x 10-7 s-1 was calculated, equivalent to a deposition rate of 0.08 cm s-1, in good agreement with deposition rates used in global models. However, owing to the dependence on wind speed, the uptake rates calculated
showed substantial range and the calculated contribution of ocean deposition to total destruction (uptake and OH destruction) varied from approximately 20% to 60%.

Significant growth in surface ozone at Mace Head, Ireland, 1987–2003 Significant growth in surface ozone at Mace Head, Ireland, 1987–2003

Date added: 08/07/2004
Date modified: 07/23/2009
Filesize: 501.27 kB

Significant growth in surface ozone at Mace Head, Ireland, 1987-2003 P.G. Simmonds, R.G. Derwent, A.L. Manning, G. Spain Atmos. Environ., 38, 4769-4778, 2004


Abstract

 

Background ozone O3 observations at Mace Head on the west coast of Ireland since 1987 show a significant positive trend of 0.49 ± 0.19 ppb year-1 through to 2003. Increasing trends are observed for all seasons, with the largest trends during the winter season, 0.63±0.31 ppb year-1 and the smallest trends during the summer, 0.39 ± 0.25 ppb year-1. However, this growth rate has not been consistent over time with a major anomaly evident in 1998-1999. This major O3 perturbation is correlated with variations of CO2, CO, CH4, H2 and CH3Cl, which are likely due to large-scale biomass burning events in tropical and boreal regions during 1997-1999 coupled with an intense El Niño event. Over the 16 years of observations background O3 has increased by about 8 ppb (∼ 24%) in the clean oceanic sectors representative of the Northern Hemisphere marine boundary layer.

 

Isoprene and other non-methane hydrocarbons from seaweeds a source of reactive hydrocarbons to Isoprene and other non-methane hydrocarbons from seaweeds a source of reactive hydrocarbons to

Date added: 08/07/2004
Date modified: 07/24/2009
Filesize: 287.26 kB

BROADGATE, W.J., MALIN, G., KÜPPER, F.C., THOMPSON, A. & LISS, P.S. 2004. Isoprene and other non-methane hydrocarbons from seaweeds: a source of reactive hydrocarbons to the atmosphere. Marine Chemistry 88(1-2): 61-73. doi:10.1016/j.marchem.2004.02.002.


Abstract

 

Non-methane hydrocarbons (NMHCs) are produced naturally in the ocean and by terrestrial vegetation. Owing to its high reactivity and flux, isoprene (2-methyl-1,3-butadiene) is important in controlling the balance of atmospheric oxidants, and altering air quality on both local and global scales. Here we show, for the first time, that macroalgae (seaweeds) emit isoprene and a number of other non-methane hydrocarbons (NMHCs). We observed NMHC concentrations in rockpools containing macroalgae and estimated fluxes to the atmosphere over a full diurnal cycle. Emissions at our temperate coastal site (Mace Head, Ireland) in autumn are intermediate in magnitude between terrestrial and ocean fluxes (on a unit area basis), and may contribute significant concentrations to the local atmosphere. We also carried out a series of controlled laboratory experiments focusing on isoprene, in natural and artificial light, and under different temperature conditions involving red (Chondrus crispus, Asparagopsis armata), green (Ulva intestinalis, formerly known as Enteromorpha intestinalis) and brown (Laminaria digitata, Ascophyllum nodosum, Pelvetia canaliculata, Fucus vesiculosus, Fucus serratus, Halidrys siliquosa and Laminaria saccharina) macroalgae commonly found on the west coast of Ireland. We observed NMHC emissions from all the algae investigated and emissions were dominated by alkenes. Production is species-dependent, temperature-dependent and related to light availability. We discuss our observations in the context of what is known about the production of isoprene and ethene in higher plants.

 

Field intercomparison of filter pack and impactor sampling for aerosol nitrate, ammonium, and s Field intercomparison of filter pack and impactor sampling for aerosol nitrate, ammonium, and s

Date added: 08/07/2004
Date modified: 07/24/2009
Filesize: 759.95 kB

Field Intercomparison of Filter Pack and Impactor Sampling for Aerosol Nitrate, Ammonium, and Sulphate at Coastal and Inland Sites, Z. Huang, R.M. Harrison, A.G. Allen, J.D. James, R.M. Tilling and J. Yin, Atmos. Res., 71, 215-232 (2004).


Abstract


An intercomparison has been performed on the coarse (>2.5 μm) and fine fraction (<2.5 μm) mass concentrations of particulate nitrate, ammonium, and sulphate determined simultaneously by filter pack and MOUDI samplers. Five intensive field campaigns have been carried out in summer and winter seasons, both at coastal sites (Mace Head, Ireland, and Tenerife, Spain) and at an inland site (University of Birmingham, West Midlands, UK). Comparison between particle sulphate measurements shows that sulphate measurements are the same with both filter pack and MOUDI, independent of sampling site or season. For both nitrate and ammonium, the MOUDI results are observed to be usually less than those from the filter pack, especially in the case of polluted air masses. During periods when the measured concentration products [NH3][HNO3] are low (<0.1 ppbv2), the ammonium concentrations obtained with the two samplers are matched very well with each other, but for nitrate, the filter pack system provides 15% higher mass concentrations than the MOUDI which are attributable to different inlet efficiencies. During more polluted periods, however, when there are high levels of gaseous ammonia and nitric acid in the atmosphere (with the measured concentration products [NH3][HNO3]>0.1 ppbv2), significantly negative sampling artefacts are observed for both nitrate and ammonium concentrations obtained with the impactor relative to the filter pack. Nevertheless, it is shown that both filter pack and MOUDI are capable of collecting ammonium nitrate from polluted air masses although the absolute efficiency is unknown. From the measurements obtained with the MOUDI in summertime at both coastal and inland sites, it is observed that about 64% of collected particle nitrate is present in the coarse (>2.5 μm) mode; but in wintertime, only about 29% of particle nitrate is found to reside in the coarse particles collected at the inland site. The lower efficiency of the MOUDI for ammonium nitrate relative to the Teflon filter is in marked contrast to the reported higher efficiency of the Berner impactor than the Teflon filter for sampling nitrate from polluted air.

 

Novel iodine chemistry in the marine boundary layer Novel iodine chemistry in the marine boundary layer

Date added: 08/07/2004
Date modified: 07/23/2009
Filesize: 189.32 kB

Saiz-Lopez, A., and J. M. C. Plane (2004), Novel iodine chemistry in the marine boundary layer, Geophys. Res. Lett., 31, L04112, doi:10.1029/2003GL019215.


Abstract


The atmospheric chemistry of iodine is important for several reasons, including the influence of iodine oxides on the oxidising capacity of the troposphere, the formation of new particles, and the enrichment of iodine in marine aerosols and the transport of this essential dietary element to the continents. It is shown here that a substantial iodine source is I2, most likely emitted from macro-algae at low tide. This source accounts for the daytime production of new particles in the coastal marine boundary layer, and also explains the discovery of significant night-time levels of iodine oxides.

 

Bromine oxide in the mid-latitude marine boundary layer Bromine oxide in the mid-latitude marine boundary layer

Date added: 08/07/2004
Date modified: 07/27/2009
Filesize: 153.87 kB

Saiz-Lopez, A., J. M. C. Plane, and J. A. Shillito (2004), Bromine oxide in the mid-latitude marine boundary layer, Geophys. Res. Lett., 31, L03111, doi:10.1029/2003GL018956.


Abstract


We report direct observations of bromine oxide (BrO) in the mid-latitude marine boundary layer (MBL), using long-path Differential Optical Absorption Spectroscopy (DOAS). The measurements were made at the Mace Head observatory on the west coast of Ireland. Over six days of observations, the BrO concentration varied from below the detection limit (≈0.8 parts per trillion (ppt)) at night, to a maximum daytime concentration of 6.5 ppt. At the average daytime concentration of 2.3 ppt, BrO causes significant O3 depletion in the MBL through catalytic cycles involving the iodine oxide and hydroperoxy radicals, and also oxidises dimethyl sulfide much more rapidly than the hydroxyl radical. A post-sunrise pulse of BrO was observed, consistent with the build up of photolabile precursors produced by heterogeneous reactions on sea-salt aerosol during the previous night. This indicates that significant bromine activation occurs over the open ocean.

 

MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN

Date added: 08/06/2004
Date modified: 07/23/2009
Filesize: 33.16 kB

R. Sommariva, W.J. Bloss , L.J. Carpenter, N. Carslaw, A.-L. Haggerstone, D.E. Heard, A.C. Lewis, G. McFiggans, M.J. Pilling, J.M.C. Plane,MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN, Geophysical Research Abstracts, Vol. 6, 00232, 2004


Abstract

 

The North Atlantic Marine Boundary Layer Experiment (NAMBLEX) campaign took place at the Mace Head Atmospheric Research Station, Ireland, in July-September 2002. An extensive set of measurements was taken during the campaign including NMHCs, NOx, HCHO, peroxides, photolysis rates, aerosols and radical species (OH, HO2, HO2+RO2, NO3, IO and BrO). Several different zero-dimensional box models based on the Master Chemical Mechanism (MCMv3.1) with different levels of chemical complexity have been used to study the HOx radicals chemistry under comparatively unpolluted conditions. The comparison between the model results and the measurements, based on the FAGE (Fluorescence Assay by Gas Expansion) measurements is satisfactory for OH, but HO2 is overestimated by almost a factor of two.
The effect of constraining the models to the measured oxygenates (methanol, acetaldehyde and acetone) and the effect of IO and BrO on HOx chemistry have been investigated. Aerosol uptake treatment for the relevant species has been  improved with respect to previous analyses by using a transition regime expression, which resulted in better agreement between modelled and measured HOx. A detailed study of the radical chemistry on selected days using a rate of production/ destruction analysis, shows the importance of previously unmeasured oxygenated compounds and of halogen chemistry on the HOx budget in the Marine Boundary Layer.

 

Modelling the HOx Radicals during the NAMBLEX campaign Modelling the HOx Radicals during the NAMBLEX campaign

Date added: 08/06/2004
Date modified: 09/11/2009
Filesize: 33.16 kB

R. Sommariva, W.J. Bloss , L.J. Carpenter, N. Carslaw, A.-L. Haggerstone, D.E. Heard, A.C. Lewis, G. McFiggans, M.J. Pilling, J.M.C. Plane,MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN, Geophysical Research Abstracts, Vol. 6, 00232, 2004


Abstract

 

The North Atlantic Marine Boundary Layer Experiment (NAMBLEX) campaign took place at the Mace Head Atmospheric Research Station, Ireland, in July-September 2002. An extensive set of measurements was taken during the campaign including NMHCs, NOx, HCHO, peroxides, photolysis rates, aerosols and radical species (OH, HO2, HO2+RO2, NO3, IO and BrO). Several different zero-dimensional box models based on the Master Chemical Mechanism (MCMv3.1) with different levels of chemical complexity have been used to study the HOx radicals chemistry under comparatively unpolluted conditions. The comparison between the model results and the measurements, based on the FAGE (Fluorescence Assay by Gas Expansion) measurements is satisfactory for OH, but HO2 is overestimated by almost a factor of two.
The effect of constraining the models to the measured oxygenates (methanol, acetaldehyde and acetone) and the effect of IO and BrO on HOx chemistry have been investigated. Aerosol uptake treatment for the relevant species has been  improved with respect to previous analyses by using a transition regime expression, which resulted in better agreement between modelled and measured HOx. A detailed study of the radical chemistry on selected days using a rate of production/ destruction analysis, shows the importance of previously unmeasured oxygenated compounds and of halogen chemistry on the HOx budget in the Marine Boundary Layer.

MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN

Date added: 08/06/2004
Date modified: 07/23/2009
Filesize: 33.16 kB

R. Sommariva, W.J. Bloss , L.J. Carpenter, N. Carslaw, A.-L. Haggerstone, D.E. Heard, A.C. Lewis, G. McFiggans, M.J. Pilling, J.M.C. Plane,MODELLING HOX RADICALS DURING THE NAMBLEX CAMPAIGN, Geophysical Research Abstracts, Vol. 6, 00232, 2004


Abstract

 

The North Atlantic Marine Boundary Layer Experiment (NAMBLEX) campaign took place at the Mace Head Atmospheric Research Station, Ireland, in July-September 2002. An extensive set of measurements was taken during the campaign including NMHCs, NOx, HCHO, peroxides, photolysis rates, aerosols and radical species (OH, HO2, HO2+RO2, NO3, IO and BrO). Several different zero-dimensional box models based on the Master Chemical Mechanism (MCMv3.1) with different levels of chemical complexity have been used to study the HOx radicals chemistry under comparatively unpolluted conditions. The comparison between the model results and the measurements, based on the FAGE (Fluorescence Assay by Gas Expansion) measurements is satisfactory for OH, but HO2 is overestimated by almost a factor of two.
The effect of constraining the models to the measured oxygenates (methanol, acetaldehyde and acetone) and the effect of IO and BrO on HOx chemistry have been investigated. Aerosol uptake treatment for the relevant species has been  improved with respect to previous analyses by using a transition regime expression, which resulted in better agreement between modelled and measured HOx. A detailed study of the radical chemistry on selected days using a rate of production/ destruction analysis, shows the importance of previously unmeasured oxygenated compounds and of halogen chemistry on the HOx budget in the Marine Boundary Layer.

 

Uptake of methanol to the North Atlantic Ocean surface Uptake of methanol to the North Atlantic Ocean surface

Date added: 08/06/2004
Date modified: 07/23/2009
Filesize: 417.44 kB

Carpenter, L. J., A. C. Lewis, J. R. Hopkins, K. A. Read, I. D. Longley, and M. W. Gallagher (2004), Uptake of methanol to the North Atlantic Ocean surface, Global Biogeochem. Cycles, 18, GB4027, doi:10.1029/2004GB002294.


Abstract


An anticorrelation between atmospheric methanol (CH3OH) concentrations and wind speed and a positive correlation between dimethylsulphide (DMS) concentrations and wind speed have been observed at the coastal air monitoring site of Mace Head in Ireland, during a period of cyclonic activity in which the averaged surface wind speed changed substantially as a low-pressure system evolved over the northeast Atlantic. These observations suggest a net air-to-sea flux of CH3OH. This conclusion is supported by the good agreement between the wind speed dependencies of the measured gas concentrations and theoretical predictions using wind-induced turbulent gas transfer velocities of DMS and CH3OH calculated from a resistance model, embedded in a photochemical box model. For a wind speed of 8 m s−1, an ocean deposition rate of methanol of between 0.02 and 0.33 cm s−1 is calculated, with a best estimate of 0.09 cm s−1, in good agreement with deposition rates used in global models and derived from atmospheric budgets. The large uncertainty in the calculated deposition rates is due almost entirely to the uncertainty in the degree of saturation of methanol in the surface ocean, highlighting the critical requirement for measurements of methanol in seawater. Owing to the dependence on wind speed, the deposition rates calculated showed substantial range and the calculated contribution of ocean deposition to total loss of CH3OH (ocean uptake and gas phase OH oxidation) varied from approximately 20% to 60%.

 

Rapid growth of hydrofluorocarbon 134a and hydrochlorofluorocarbons 141b, 142b, and 22 from Adv Rapid growth of hydrofluorocarbon 134a and hydrochlorofluorocarbons 141b, 142b, and 22 from Adv

Date added: 08/06/2004
Date modified: 07/23/2009
Filesize: 791.05 kB

O'Doherty, S., et al. (2004), Rapid growth of hydrofluorocarbon 134a and hydrochlorofluorocarbons 141b, 142b, and 22 from Advanced Global Atmospheric Gases Experiment (AGAGE) observations at Cape Grim, Tasmania, and Mace Head, Ireland, J. Geophys. Res., 109, D06310, doi:10.1029/2003JD004277.


Abstract


An update of in situ Advanced Global Atmospheric Gases Experiment (AGAGE) hydrofluorocarbon (HFC)/hydrochlorofluorocarbon (HCFC) measurements made at Mace Head, Ireland, and Cape Grim, Tasmania, from 1998 to 2002 are reported. HCFC-142b, HCFC-141b, HCFC-22 and HFC-134a show continued rapid growth in the atmosphere at mean rates of 1.1, 1.6, 6.0, and 3.4 ppt/year, respectively. Emissions inferred from measurements are compared to recent estimates from consumption data. Minor updates to the industry estimates of emissions are reported together with a discussion of how to best determine OH concentrations from these trace gas measurements. In addition, AGAGE measurements and derived emissions are compared to those deduced from NOAA-Climate Monitoring and Diagnostics Laboratory flask measurements (which are mostly made at different locations). European emission estimates obtained from Mace Head pollution events using the Nuclear Accident Model (NAME) dispersion model and the best fit algorithm (known as simulated annealing) are presented as 3-year rolling average emissions over Europe for the period 1999–2001. Finally, the measurements of HCFC-141b, HCFC-142b, and HCFC-22 discussed in this paper have been combined with the Atmospheric Lifetime Experiment (ALE)/Global Atmospheric Gases Experiment (GAGE)/AGAGE measurements of CFC-11, CFC-12, CFC-113, CCl4, and CH3CCl3 to produce the evolution of tropospheric chlorine loading.

 

Halogenated greenhouse gases at the Swiss High Alpine Site of Jungfraujoch (3580 m asl) Continu Halogenated greenhouse gases at the Swiss High Alpine Site of Jungfraujoch (3580 m asl) Continu

Date added: 08/06/2004
Date modified: 07/24/2009
Filesize: 1.93 MB

Reimann, S., D. Schaub, K. Stemmler, D. Folini, M. Hill, P. Hofer, B. Buchmann, P. G. Simmonds, B. R. Greally, and S. O'Doherty (2004), Halogenated greenhouse gases at the Swiss High Alpine Site of Jungfraujoch (3580 m asl): Continuous measurements and their use for regional European source allocation, J. Geophys. Res., 109, D05307, doi:10.1029/2003JD003923.


Abstract


At the high Alpine site of Jungfraujoch (3580 m asl), 23 halogenated greenhouse gases are measured quasi-continuously by gas chromatography-mass spectrometry (GCMS). Measurement data from the years 2000–2002 are analyzed for trends and pollution events. Concentrations of the halogenated trace gases, which are already controlled in industrialized countries by the Montreal Protocol (e.g., CFCs) were at least stable or declining. Positive trends in the background concentrations were observed for substances which are used as CFC-substitutes (hydrofluorocarbons, hydrochlorofluorocarbons). Background concentrations of the hydrofluorocarbons at the Jungfraujoch increased from January 2000 until December 2002 as follows: HFC 134a (CF3CH2F) from 15 to 27 ppt, HFC 125 (CF3CHF2) from 1.4 to 2.8 ppt, and HFC 152a (CHF2CH3) from 2.3 to 3.2 ppt. For HFC 152a, a distinct increase of its concentration magnitude during pollution events was observed from 2000 to 2002, indicating rising European emissions for this compound. Background concentrations of all measured compounds were in good agreement with similar measurements at Mace Head, Ireland. On the other hand, peak concentrations were significantly higher at the Jungfraujoch. This finding is due to the proximity to potent European sources, foremost in southern Europe. The average ratio of halocarbons versus carbon monoxide (CO) concentrations above their baseline values was used to estimate source strengths for the part of Europe which most influences the Jungfraujoch during pollution events. HFCs emission estimates from Jungfraujoch tend to be higher than figures at Mace Head (Ireland) from the end of the 1990s, which either reflects the increased use of these compounds or the closer location of Jungfraujoch to major southern European sources. Transport of polluted European boundary layer air masses to the high Alpine site was observed especially during frontal passages, foehn events, and thermal lifting of air masses in summer. The measurement data during the periods when the Jungfraujoch was under the influence of the polluted boundary layer were used in combination with concurrent air mass trajectories to allocate above baseline halocarbon concentrations to specific European source regions.

 

Characterization of individual airborne particles by using aerosol time-of-flight mass spectrom Characterization of individual airborne particles by using aerosol time-of-flight mass spectrom

Date added: 08/06/2004
Date modified: 07/27/2009
Filesize: 425.52 kB

Dall'Osto, M., D. C. S. Beddows, R. P. Kinnersley, R. M. Harrison, R. J. Donovan, and M. R. Heal (2004), Characterization of individual airborne particles by using aerosol time-of-flight mass spectrometry at Mace Head, Ireland, J. Geophys. Res., 109, D21302, doi:10.1029/2004JD004747.


Abstract


An aerosol time-of-flight mass spectrometer was deployed at Mace Head (Ireland) during August 2002. The measurements provide qualitative chemical composition and size distribution (0.3–3 μm) information for single particles. Three broad categories of particles: sea salt, dust, and carbon-containing particles were identified and apportioned, and their temporal evolution (1 hour resolution) is described. Aerosol sources were correlated with meteorological factors and with air mass trajectories, demonstrating long-range transport of different continental air masses from Europe, Africa, and America. The major class of particles was derived from sea salt and was subdivided into pure, mixed, and aged sea salt according to the extent of displacement of chloride by nitrate. Two types of dust particles were found mainly in the coarse mode (>1 μm); the former, thought to originate from the Sahara, presented an aluminium/silicon signature, while the latter, of more local origin, had a calcium-rich composition. Carbon-containing particles were mainly distributed in the fine mode (<1 μm) and associated with different chemical species in different size modes, suggesting different mechanisms of formation.

 

Organic aerosol formation via sulphate cluster activation Organic aerosol formation via sulphate cluster activation

Date added: 08/06/2004
Date modified: 07/03/2009
Filesize: 667.33 kB

Kulmala, M., V.-M. Kerminen, T. Anttila, A. Laaksonen, and C. D. O'Dowd (2004), Organic aerosol formation via sulphate cluster activation, J. Geophys. Res., 109, D04205, doi:10.1029/2003JD003961.


Abstract


The formation of aerosols, and subsequent cloud condensation nuclei, remains one of the least understood atmospheric processes upon which global climate change critically depends. Under atmospheric conditions, the process of homogeneous nucleation (formation of stable clusters ∼ 1 nm in size), and their subsequent growth into new particles (>3 nm), determines the aerosol and cloud nuclei population, yet, hitherto, no theory has elucidated the new particle formation phenomenon in detail. In this study, we present a new theory which provides a mechanistic explanation for new particle formation via activation of stable inorganic clusters by organic vapors. The new nano-particle activation theory is analogous to Köhler theory which describes cloud formation in a supersaturated water vapor field but differs in that it describes the activation of inorganic stable nano-clusters into aerosol particles in a supersaturated organic vapor which initiates spontaneous and rapid growth of clusters. Inclusion of the new theory into aerosol formation models predicts that increases in organic vapor densities lead to even greater increases in particle production, which, in turn, will influence the global radiative cooling effect of atmospheric aerosols.

 

Time series analysis of long-term data sets of atmospheric mercury concentrations Time series analysis of long-term data sets of atmospheric mercury concentrations

Date added: 08/05/2004
Date modified: 07/23/2009
Filesize: 431.28 kB

Temme C, Ebinghaus R, Einax JW, Steffen A, Schroeder WH. Time series analysis of long-term data sets of atmospheric mercury concentrations. Anal Bioanal Chem. 2004; 380:49350


Abstract


Different aspects and techniques of time series analysis were used to investigate long-term data sets of atmospheric mercury in the Northern Hemisphere. Two perennial time series from different latitudes with different seasonal behaviour were chosen: first, Mace Head on the west coast of Ireland (53°20′N, 9°54′W), representing Northern Hemispherical background conditions in Europe with no indications for so-called atmospheric mercury depletion events (AMDEs); and second, Alert, Canada (82°28′N, 62°30′W), showing strong AMDEs during Arctic springtime. Possible trends were extracted and forecasts were performed by using seasonal decomposition procedures, autoregressive integrated moving average (ARIMA) methods and exponential smoothing (ES) techniques. The application of time series analysis to environmental data is shown in respect of atmospheric long-term data sets, and selected advantages are discussed. Both time series have not shown any statistically significant temporal trend in the gaseous elemental mercury (GEM) concentrations since 1995, representing low Northern Hemispherical background concentrations of 1.72±0.09 ng m−3 (Mace Head) and 1.55±0.18 ng m−3 (Alert), respectively. The annual forecasts for the GEM concentrations in 2001 at Alert by two different techniques were in good agreement with the measured concentrations for this year.

 

AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001 AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001

Date added: 08/01/2004
Date modified: 07/27/2009
Filesize: 593.54 kB

Simmonds, P.; Derwent, R.; Manning, A.; Fraser, P.; Krummel, P.; O'Doherty, S.; Prinn, R.; Cunnold, D.; Miller, B.; Wang, H.; Ryall, D.; Porter, L.; Weiss, R.; Salameh, P. ,AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001, Journal of Atmospheric Chemistry, pg 1573-0662


Abstract


In situ AGAGE GC-MS measurements of methyl bromide (CH3Br) and methyl chloride (CH3Cl) at Mace Head, Ireland and Cape Grim, Tasmania (1998–2001) reveal a complex pattern of sources. At Mace Head both gases have well-defined seasonal cycles with similar average annual decreases of 3.0% yr−1 (CH3Br) and 2.6% yr−1 (CH3Cl), and mean northern hemisphere baseline mole fractions of 10.37 ± 0.05 ppt and 535.7 ± 2.2 ppt, respectively. We have used a Lagrangian dispersion model and local meteorological data to segregate the Mace Head observations into different source regions, and interpret the results in terms of the known sources and sinks of these two key halocarbons. At Cape Grim CH3Br and CH3Cl also show annual decreases in their baseline mixing ratios of 2.5% yr−1 and 1.5% yr−1, respectively. Mean baseline mole fractions were 7.94 ± 0.03 ppt (CH3Br) and 541.3 ± 1.1 ppt (CH3Cl). Although CH3Cl has astrong seasonal cycle there is no well-defined seasonal cycle in the Cape Grim CH3Br record. The fact that both gases are steadily decreasing in the atmosphere at both locations implies that a change has occurred which is affecting a common, major source of both gases (possibly biomass burning) and/or their major sink process (destruction by hydroxyl radical).

AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001 AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001

Date added: 08/01/2004
Date modified: 06/30/2009
Filesize: 593.54 kB

Simmonds, P.; Derwent, R.; Manning, A.; Fraser, P.; Krummel, P.; O'Doherty, S.; Prinn, R.; Cunnold, D.; Miller, B.; Wang, H.; Ryall, D.; Porter, L.; Weiss, R.; Salameh, P. ,AGAGE Observations of Methyl Bromide and Methyl Chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998–2001, Journal of Atmospheric Chemistry, pg 1573-0662


Abstract


In situ AGAGE GC-MS measurements of methyl bromide (CH3Br) and methyl chloride (CH3Cl) at Mace Head, Ireland and Cape Grim, Tasmania (1998–2001) reveal a complex pattern of sources. At Mace Head both gases have well-defined seasonal cycles with similar average annual decreases of 3.0% yr−1 (CH3Br) and 2.6% yr−1 (CH3Cl), and mean northern hemisphere baseline mole fractions of 10.37 ± 0.05 ppt and 535.7 ± 2.2 ppt, respectively. We have used a Lagrangian dispersion model and local meteorological data to segregate the Mace Head observations into different source regions, and interpret the results in terms of the known sources and sinks of these two key halocarbons. At Cape Grim CH3Br and CH3Cl also show annual decreases in their baseline mixing ratios of 2.5% yr−1 and 1.5% yr−1, respectively. Mean baseline mole fractions were 7.94 ± 0.03 ppt (CH3Br) and 541.3 ± 1.1 ppt (CH3Cl). Although CH3Cl has astrong seasonal cycle there is no well-defined seasonal cycle in the Cape Grim CH3Br record. The fact that both gases are steadily decreasing in the atmosphere at both locations implies that a change has occurred which is affecting a common, major source of both gases (possibly biomass burning) and/or their major sink process (destruction by hydroxyl radical).

Modelling the formation of organic particles in the atmosphere Modelling the formation of organic particles in the atmosphere

Date added: 08/01/2004
Date modified: 07/03/2009
Filesize: 1.72 MB

Anttila, T., V. -M. Kerminen, M. Kulmala, A. Laaksonen, and C. D. O'Dowd, Modelling the formation of organic particles in the atmosphere, Atmospheric Chemistry and Physics, Vol. 4, pp 1071-1083, 2004.


Abstract


Particle formation resulting from activation of inorganic stable clusters by a supersaturated organic vapour was investigated using a numerical model. The applied aerosol dynamic model included a detailed description of the activation process along with a treatment of the appropriate aerosol and gas-phase processes. The obtained results suggest that both gaseous sulphuric acid and organic vapours contribute to organic particle formation in continental background areas. The initial growth of freshly-nucleated clusters is driven mainly by condensation of gaseous sulphuric acid and by a lesser extent self-coagulation. After the clusters have reached sizes of around 2 nm in diameter, low-volatile organic vapours start to condense spontaneously into the clusters, thereby accelerating their growth to detectable sizes. A shortage of gaseous sulphuric acid or organic vapours limit, or suppress altogether, the particle formation, since freshly-nucleated clusters are rapidly coagulated away by pre-existing particles. The obtained modelling results were applied to explaining the observed seasonal cycle in the number of aerosol formation events in a continental forest site.

Measurement and analysis of aerosol and black carbon in the southwestern United States and Panama an Measurement and analysis of aerosol and black carbon in the southwestern United States and Panama an

Date added: 08/01/2004
Date modified: 07/02/2009
Filesize: 856.64 kB
Junker, C., Sheahan, J., Jennings, S.G., O’Brien, P., Hinds, B.D., Martinez-Tway, E., Hansen, A.D.A., White, C., Garvey, D.M., and Pinnick, R.G., 2004. Measurement and analysis of aerosol and black carbon in the Southern United States and Panama and their dependence on air mass origin, J. Geophys. Res. 109, D13201, doi: 10.1029/2003JD004066.

Abstract


Total aerosol mass loading, aerosol absorption, and black carbon (BC) content were determined from aerosol collected on 598 quartz fiber filters at a remote, semiarid site near Orogrande, New Mexico from December 1989 to October 1995. Aerosol mass was determined by weighing filters before and after exposure, and aerosol absorption was determined by measuring the visible light transmitted through loaded filter samples and converting these measurements to aerosol absorption. BC content was determined by measuring visible light transmitted through filter samples before and after firing and converting the absorption to BC mass, assuming a BC absorption cross section of 19 m2/g in the fiber filter medium. Two analyses were then performed on each of the logged variables: an autoregressive integrating moving average (ARIMA) analysis and a decomposition analysis using an autoregressive model to accommodate first-order autocorrelation. The two analyses reveal that BC mass has no statistically significant seasonal dependence at the 5% level of significance but only random fluctuations varying around an average annual value that has a long-term decreasing trend (from 0.16 to 0.11 μg/m3 during 1990–1995). Aerosol absorption, which is dominated by BC, also displays random fluctuations about an average value, and decreases from 1.9 Mm−1 to 1.3 Mm−1 during the same period. Unlike BC, aerosol mass at the Orogrande site displays distinctly different character. The analyses reveal a pronounced seasonal dependence, but no long-term trend for aerosol mass. The seasonal indices resulting from the autoregression analysis have a minimum in January (−0.78) and maximum in June (+0.58). The geometric mean value over the 1990–1995 period for aerosol mass is 16.0 μg/m3. Since BC aerosol at the Orogrande site is a product of long-range atmospheric transport, a back trajectory analysis of air masses was conducted. Back trajectory analyses indicate that air masses traversing high population centres on the west coast of the USA can lead to significant BC loading, while air masses originating from the southeast of the site tend to have less BC. Additional aerosol measurements are reported for a remote maritime site located on the Atlantic side of the former Panama Canal Zone for the 1976–1979 period, although these data have been analyzed with less statistical rigor. The average geometric mean value of aerosol mass loading for this site is 9.7 μg/m3, with a significant decreasing trend of −19% per year. The mean value of aerosol absorption is 0.59 Mm−1, with a decreasing trend of −15% per year.

Biogenically-driven organic contribution to marine aerosol Biogenically-driven organic contribution to marine aerosol

Date added: 08/01/2004
Date modified: 07/27/2009
Filesize: 296.9 kB

O'Dowd, C.D., M.C. Facchini, F. Cavalli, D. Ceburnis, M. Mircea, S. Decesari, S. Fuzzi, Y.J. Yoon, and J.P. Putaud, Biogenically-driven organic contribution to marine aerosol, Nature, doi:10.1038/nature02959,. 2004.


Abstract


Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centred on the production of aerosol from sea-salt1 and non-sea-salt sulphates2, 3. Recent field experiments, however, have shown that known aerosol production processes for inorganic species cannot account for the entire aerosol mass that occurs in submicrometre sizes4, 5, 6. Several experimental studies have pointed to the presence of significant concentrations of organic matter in marine aerosol7, 8, 9, 10, 11. There is some information available about the composition of organic matter12, 13, 14, but the contribution of organic matter to marine aerosol, as a function of aerosol size, as well as its characterization as hydrophilic or hydrophobic, has been lacking. Here we measure the physical and chemical characteristics of submicrometre marine aerosol over the North Atlantic Ocean during plankton blooms progressing from spring through to autumn. We find that during bloom periods, the organic fraction dominates and contributes 63% to the submicrometre aerosol mass (about 45% is water-insoluble and about 18% water-soluble). In winter, when biological activity is at its lowest, the organic fraction decreases to 15%. Our model simulations indicate that organic matter can enhance the cloud droplet concentration by 15% to more than 100% and is therefore an important component of the aerosol–cloud–climate feedback system involving marine biota.

Atmospheric particle formation events at Värriö measurement station in Finnish Lapland 1998–2002 Atmospheric particle formation events at Värriö measurement station in Finnish Lapland 1998–2002

Date added: 08/01/2004
Date modified: 06/30/2009
Filesize: 683.76 kB

Vehkamäki, H., M. Dal Maso, T. Hussein, R. Flanagan, A. Hyvärinen, J. Lauros, J. Merikanto, P. Mönkkönen, M. Pihlatie, K. Salminen, L. Sogacheva, T. Thum, T. M. Ruuskanen, P. Keronen, P. P. Aalto, P. Hari, K. E. J. Lehtinen, Ü. Rannik, and M. Kulmala. Atmospheric particle formation events at Värriö measurement station in Finnish Lapland 1998–2002. Atmospheric Chemistry and Physics, Vol 4, pp. 2015-2023, 2004.


Abstract

 

During the calendar years 1998-2002, 147 clear 8nm diameter particle formation events have been identified at the SMEAR I station in Värriö, northern Finland. The events have been classified in detail according to the particle formation rate, growth rate, event starting time, different trace gas concentrations and pre-existing particle concentrations as well as various meteorological conditions. The frequency of particle formation and growth events was highest during the spring months between March and May, suggesting that increasing biological activity might produce the precursor gases for particle formation. The apparent 8nm particle formation rates were around 0.1 /cm3s, and they were uncorrelated with growth rates that varied between 0.5 and 10nm/h. The air masses with clearly elevated sulphur dioxide concentrations (above 1.6ppb) came, as expected, from the direction of the Nikel and Monschegorsk smelters. Only 15 formation events can be explained by the pollution plume from these sources.

Advances in characterization of size resolved organic matter in marine aerosol over the North Atlantic Advances in characterization of size resolved organic matter in marine aerosol over the North Atlantic

Date added: 08/01/2004
Date modified: 07/27/2009
Filesize: 552.34 kB
Cavalli,F., M.C. Facchini, S. Decesari, M. Mircea, L. Emblico, S. Fuzzi, D. Ceburnis, Y.J. Yoon and C.D. O’Dowd, J.-P. Putaud and A. Dell’Acqua, Advances in characterization of size resolved organic matter in marine aerosol over the North Atlantic, J. Geophys. Res, doi:10.1029/2004JD0051377, 2004.

Abstract


Size-segregated marine aerosols were collected at Mace Head Atmospheric Research Station (Ireland) during spring and autumn 2002 corresponding with the phytoplankton bloom periods in the North Atlantic. Strict control of the sampling, air mass back trajectory analysis, and analysis of pollutant tracers allowed the selection of a set of samples representative of clean marine conditions. A comprehensive chemical characterization of both (1) water-soluble and water-insoluble organic fraction and (2) water-soluble inorganic ions was performed. The selected samples illustrated a consistent picture in terms of chemical composition. The supermicron mode predominantly comprises sea-salt aerosol with a mass concentration of 10.16 ± 0.80 μg m−3, the remainder being non-sea-salt (nss) sulphate, 0.03 ± 0.01 μg m−3, and nitrate, 0.13 ± 0.04 μg m−3. By comparison, the mass of sea salt, nss sulphate, and nitrate in the submicron mode is found to be 0.39 ± 0.08 μg m−3, 0.26 ± 0.04 μg m−3, and 0.02 ± 0.01 μg m−3, respectively. Water-soluble organic carbon (WSOC) is observed in the submicron mode with a mass concentration of 0.25 ± 0.04 μg m−3, comparable to that of nss sulphate, and in the supermicron mode with a mass concentration of 0.17 ± 0.04 μg m−3. The WSOC to total carbon (TC) ratio is found to be 0.20 ± 0.12 for the submicron fraction and 0.29 ± 0.08 for the supermicron fraction, while the black carbon (BC) to TC ratio is, on average, 0.032 ± 0.001 for both aerosol modes. The remaining carbon, water-insoluble organic carbon, contributes 0.66 ± 0.11 μg m−3 and 0.26 ± 0.06 μg m−3 to the submicron and supermicron modes, respectively and, thus, represents the dominant submicron aerosol species. Furthermore, the WSOC chemical composition comprises mainly aliphatic and only partially oxidized species and humic-like substances, resulting in appreciable surface-active properties. The observed organic matter chemical features (size-dependent concentration, hydrophobic nature of a substantial fraction of the organic matter, and low oxidized and surface-active WSOC species) are consistent with the hypothesis of a primary marine source; bubble-bursting processes, occurring at the surface of the North Atlantic Ocean during phytoplankton blooms, effectively transfer organic matter into marine aerosol particles, particularly enriching the fine-aerosol fraction.

The use of the pulse height analyser ultrafine condensation particle counter (PHA-UCPC) techniq The use of the pulse height analyser ultrafine condensation particle counter (PHA-UCPC) techniq

Date added: 09/22/2003
Date modified: 07/13/2009
Filesize: 458.51 kB

O’Dowd, C.D., P.P. Aalto, Y.J. Yoon, K. Hameri. The use the pulse height analyzer ultrafine condensation particle counter (PHA-UCPC) technique applied to sizing of nucleation mode particle of differing chemical composition. J. Aerosol. Sci. 2003. doi:10.1016/j.jaerosci.2003.08.003


Abstract


A modified white-light pulse-height analyser (PHA) TSI 3025 ultra-fine condensation particle counter (UCPC) is often used to provide fast response of aerosol size distributions between 3 and 10 nm since there is a monotonic link between initial aerosol size and nucleated droplet final size. The use of the PHA-UCPC for sizing nucleation mode particles depends on the droplet nucleation in the condenser chamber being somewhat independent of particle composition. Laboratory characterization of the PHA-UCPC for a range of chemical compositions, thought to be involved in atmospheric aerosol nucleation and growth, are presented here. Ammonium sulphate, pinic acid, cis-pinonic acid, malonic acid and an iodine oxide were studied and their PHA-UCPC calibration kernels are presented. It was found that all species possessed significantly different PHA responses. The results suggest that, unless the nano-particle chemical composition is known, then the PHA-UCPC cannot be used for measurements of aerosol size distributions. However, the PHA-UCPC, if used in parallel with mobility size distribution measurements, can help elucidate nano-particle chemical composition. Using the combination of mobility size distributions and the PHA-UCPC response during a nucleation and growth event over the boreal forest indicates that new particle formation, in this region, is driven by condensation of organic vapours.

Interpretation of roadside PM10 monitoring data from Sunderland, United Kingdom Interpretation of roadside PM10 monitoring data from Sunderland, United Kingdom

Date added: 09/22/2003
Date modified: 07/23/2009
Filesize: 739.63 kB

Price, M., Dowd, C., & Dixon, M. (2003). Interpretation of roadside PM10 monitoring data from Sunderland, United Kingdom. Environmental Monitoring and Assessment, 82, 225-241


Abstract


Roadside PM10 has been monitored by Partisol® at three sites in Sunderland between August 1997 and February 1998. The sites chosen were an inner city kerbside site; a roadside site adjacent to a dual carriageway on the outskirts of Sunderland with an open aspect; and a rural site. The results indicate that there is a seasonal variation in the relationship between the sites in terms of monitored PM10. In the winter there is a poor correlation between the sites whereas in the summer significant correlations are obtained. Of the sites monitored PM10 is consistently highest at the inner city roadside site. During the summer, exceedances of the U.K. 50 μg m-3 standard (DETR, 2000) are associated with conditions suitable for the build-up of photochemical pollution however during the winter period exceedances are recorded during a variety of weather conditions. At the dual carriageway site PM2.5 has also been recorded and contributions to measured PM10 are 77% in summer and 68% in winter. The results illustrate a number of inconsistencies between this study utilising the Partisol® and others reporting results where PM10 has been monitored by TEOM®.

Intercomparison Of Formaldehyde Intercomparison Of Formaldehyde

Date added: 08/31/2003
Date modified: 07/23/2009
Filesize: 36.97 kB

T.J.Still , G.Mills, S. Al-Haider, P.W Seakins, P.Quincy, N.Martin , INTERCOMPARISON OF FORMALDEHYDE

Geophysical Research Abstracts, Vol. 6, 03925, 2004, SRef-ID: 1607-7962/gra/EGU04-A-03925 ,European Geosciences Union 2004


Abstract

 

Formaldehyde is one of the most abundant gas phase carbonyl compounds present in the troposphere, which is emitted directly, and produced from photo-oxidation of biogenic and anthropogenic volatile organic compounds. The subsequent removal process of formaldehyde generates substantial amounts of HO2 radicals, which ultimately result in formation of ozone. Consequently formaldehyde has a strong influence on the global mixing ratio of ozone and HOx radicals, which govern the oxidising capacity of the troposphere. An apparatus has been developed for the direct determination of ambient, atmospheric formaldehyde using gas chromatography with an argon doped, pulsed discharge helium ionization detector. Absolute values are obtained via calibration with a permeation source. The relatively high duty cycle (˜11 hr-1) allows measurements to be taken on timescales that are short compared to the atmospheric lifetime of formaldehyde. A detection limit of 42 pptv is calculated. This instrument was deployed to the West Coast of Ireland for the North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Formaldehyde was also measured using an indirect fluorometric technique, and the results of the comparison are presented. Similar diurnal profiles are observed for both methods although they have slightly different dynamic ranges, and there was a discrepancy in the absolute values. The instruments were then tested for a linear response to atmospheric formaldehyde, and for any interferences due to ozone and water, at the National Physics Laboratory. The results demonstrated that both instruments have a linear response to formaldehydeup to 8.6 ppbv. The ozone interference experiments show that each of the techniques have a response due to ozone but of different magnitudes. It has not been possible to fully characterise the water interference in the gas chromatography technique, whilst the fluormetric method was found not to have an interference from this source. Box modelling studies predict formaldehyde concentrations comparable with our measurements and indicate that decomposition of oxygenates (e.g. CH3OH, CH3CHO), contribute significantly to the observed formaldehyde  concentrations.

A two-column method for long-term monitoring of non-methanehydrocarbons (NMHCs) and oxygenated volat A two-column method for long-term monitoring of non-methanehydrocarbons (NMHCs) and oxygenated volat

Date added: 08/31/2003
Date modified: 07/23/2009
Filesize: 174.39 kB

Hopkins, J. R., Read, K. A., and Lewis, A. C.: A Two Column Method for Long-term Monitoring of Non-Methane Hydrocarbons (NMHCs) and Oxygenated Volatile Organic Compounds, J. Envir. Mon., 5, 8–13, 2003.


Abstract


 

A method has been developed for concurrent analysis of C2–C7 hydrocarbons and C2–C5 oxygenated volatile organic compounds (o-VOCs) including alcohols, aldehydes, ketones and ethers. A multi-bed, Peltier-cooled adsorbent trap, consisting of Carboxen 1000 and Carbopack B, was used to acquire one sample per hour. Upon injection the sample was split in an approximately 50 : 50 ratio between a 50 m aluminium oxide (Al2O3) porous layer open tubular (PLOT) column and a 10 m LOWOX column. Eluents from each column were then analysed using flame ionisation detection (FID). Regular calibration of the system was performed using a standard cylinder mixture at the parts per billion by volume (ppbV) level for non-methane hydrocarbons (NMHCs) and a permeation tube method for the oxygenated species. The system is fully automated with NMHC detection limits between 1 and 10 parts per trillion by volume (pptV) and o-VOC detection limits between 10 and 40 pptV.

The North Atlantic Oscillation controls air Pollution transport to the Artic Atmos Chem Phys Comments The North Atlantic Oscillation controls air Pollution transport to the Artic Atmos Chem Phys Comments

Date added: 08/26/2003
Date modified: 08/05/2009
Filesize: 944.42 kB

Eckhardt, S., Stohl, A., Beirle, S., Spichtinger, N., James, P., Forster, C., Junker, C., Wagner, T., Platt, U., and Jennings, S. G.: The North Atlantic Oscillation controls air pollution transport to the Arctic, Atmos. Chem. Phys. Discuss., 3, 3222-3240, 2003


Abstract


This paper studies the interannual variability of pollution pathways from northern hemisphere (NH) continents into the Arctic. Using a 1-year model simulation of the dispersion of passive tracers representative of anthropogenic emissions from NH continents, we show that the North Atlantic Oscillation (NAO) exerts a strong control on the pollution transport into the Arctic, particularly in winter and spring. For tracer lifetimes of 5 (30) days, surface concentrations in the Arctic winter are enhanced by about 70% (30%) during high phases of the NAO (in the following referred to as NAO+) compared to its low phases (NAO). This is mainly due to great differences in the pathways of European pollution during NAO+ and NAO phases, respectively, but reinforced by North American pollution, which is also enhanced in the Arctic during NAO+ phases. In contrast, Asian pollution in the Arctic does not significantly depend on the NAO phase. The model results are confirmed using remotely-sensed NO2 vertical atmospheric columns obtained from seven years of satellite measurements, which show enhanced northward NO2 transport and reduced NO2 outflow into the North Atlantic from Central Europe during NAO+ phases. Surface measurements of carbon monoxide (CO) and black carbon at high-latitude stations further corroborate the overall picture of enhanced Arctic pollution levels during NAO+ phases.

The North Atlantic Oscillation controls air Pollution transport to the Arctic The North Atlantic Oscillation controls air Pollution transport to the Arctic

Date added: 08/26/2003
Date modified: 08/05/2009
Filesize: 753.2 kB

Eckhardt, S., Stohl, A., Beirle, S., Spichtinger, N., James, P., Forster, C., Junker, C., Wagner, T., Platt, U., and Jennings, S. G.: The North Atlantic Oscillation controls air pollution transport to the Arctic, Atmos. Chem. Phys., 3, 1769-1778, 2003.


Abstract


This paper studies the interannual variability of pollution pathways from northern hemisphere (NH) continents into the Arctic. Using a 15-year model simulation of the dispersion of passive tracers representative of anthropogenic emissions from NH continents, we show that the North Atlantic Oscillation (NAO) exerts a strong control on the pollution transport into the Arctic, particularly in winter and spring. For tracer lifetimes of 5 (30) days, surface concentrations in the Arctic winter are enhanced by about 70% (30%) during high phases of the NAO (in the following referred to as NAO+) compared to its low phases (NAO-). This is mainly due to great differences in the pathways of European pollution during NAO+ and NAO- phases, respectively, but reinforced by North American pollution, which is also enhanced in the Arctic during NAO+ phases. In contrast, Asian pollution in the Arctic does not significantly depend on the NAO phase. The model results are confirmed using remotely-sensed NO2 vertical atmospheric columns obtained from seven years of satellite measurements, which show enhanced northward NO2 transport and reduced NO2 outflow into the North Atlantic from Central Europe during NAO+ phases. Surface measurements of carbon monoxide (CO) and black carbon at high-latitude stations further corroborate the overall picture of enhanced Arctic pollution levels during NAO+ phases

Long-term measurements of the concentrations of halocarbons in an urban area of Kraków, Poland Long-term measurements of the concentrations of halocarbons in an urban area of Kraków, Poland

Date added: 08/07/2003
Date modified: 07/24/2009
Filesize: 210.57 kB

Lasa J., Śliwka I. Long.term measurements of the concentrations of halocarbons in an urban area of Kraków, Poland. Applied Energy, 75 (2003), 155-163.


Abstract


The results of the measurements of the concentrations of freons (F-11 and F-113), chloroform (CHCl3), trichloroethane (CH3CCl3) and carbon tetrachloride (CCl4) in air are presented. The data concern concentration measurements that have been conducted in Krakow since half way through 1997 to the end of 1999. The mean monthly values of these concentrations have been compared with the data from Mace Head, the station situated at a similar longitude as Krakow. It has been concluded that, in the observed period of time, the concentrations of the pollutants in Krakow are higher than in Mace Head. The mean monthly concentrations of F-11 and CCl4 decrease in Krakow faster than in Mace Head (2.5 and 3.3 times, respectively). The concentrations of CHCl3 and CH3CCl3 decrease at both locations, but the change is greater in Krakow. In Krakow, the observed increase of F-113 is 0.13 ppt/month and has an opposite trend than in the same period at Mace Head.

Evasion of mercury from coastal and open waters of the Atlantic Ocean and the Mediterranean Sea Evasion of mercury from coastal and open waters of the Atlantic Ocean and the Mediterranean Sea

Date added: 08/07/2003
Date modified: 07/24/2009
Filesize: 240.1 kB

Gardfeldt, K., Sommar, J., Ferrara, R., Ceccarini, C., Lanzillotta, E., Munthe, J., Wangberg, I., Lindqvist, O., Pirrone N., Sprovieri, F., Pesenti, E. (2003)   Evasion of mercury from coastal and open waters of the Atlantic Ocean and the Mediterranean Sea. Atmospheric Environment. Vol. 37-S1, 73-84.


Abstract


Dissolved gaseous mercury (DGM) was measured in coastal Atlantic seawater and in the Mediterranean Sea. The Atlantic measurements were performed during September 1999 at the Mace Head Atmospheric Research Station, situated on the Irish west coast. The measurements in the Mediterranean Sea were made along a 6000 km cruise path from 14 July to 9 August 2000 in the framework of the Med-Oceanor project. Total gaseous mercury (TGM) concentrations in air were continuously measured with a 5 min time resolution using an automated mercury analyser (Tekran 2537A) during both expeditions. Paired TGM and DGM samples from all campaigns showed that the surface water was supersaturated with elemental mercury. The mercury evasion was estimated using a gas exchange model (J. Geophys. Res. 97 (1992) 7373), which uses salinity, wind speed and water temperature as independent parameters. The predicted average mercury evasion from the coastal Atlantic water was 2.7 ng m-2h-1 implying that the concentration of TGM in the Atlantic air is enhanced by mercury evasion from the sea. Measurements in different regions of the Mediterranean Sea showed spatial variations in DGM concentrations. The highest DGM concentration (∼90 pg l-1) was observed at a location in the Strait of Sicily (37° 16N 11° 52E). The mercury evasion in the eastern sector of the Mediterranean Sea (area: 32-36°N, 17-28 E) was generally higher (7.9 ng m-2h-1) than that observed in the Tyrrhenian Sea (4.2 ng m-2h-1) or in the western sector (2.5 ng m-2h-1) (areas: 38-42°N, 8-13°E and 38-41°N, 7-8°E, respectively). Estimations of mercury evasion were also made at Mediterranean coastal sites using a dynamic chamber technique. In addition, a newly developed method making continuous in situ DGM measurements possible was tested.

 

An ozone budget for the UK using measurements... ozone monitoring network; measured and modelle An ozone budget for the UK using measurements... ozone monitoring network; measured and modelle

Date added: 08/07/2003
Date modified: 07/27/2009
Filesize: 541.71 kB

Coyle M., et al., “An ozone budget for the UK: using measurements from the national ozone  monitoring network; measured and modelled meteorological data, and a 'big-leaf' resistance
analogy model of dry deposition”,  Environmental Pollution, 123 (1), 115-123, 2003.


Abstract


Data from the UK national air-quality monitoring network are used to calculate an annual mass budget for ozone (O3) production and loss in the UK boundary layer during 1996. Monthly losses by dry deposition are quantified from 1 km1 km scale maps of O3 concentration and O3 deposition velocities based on a ‘big  leaf ’ resistance analogy. The quantity of O3 deposition varies from 50 Gg-O3 month1 in the winter to over 200 Gg-O3 month1 in the summer when vegetation is actively absorbing O3. The net O3 production or loss in the UK boundary layer is found by selecting days when the UK is receiving ‘‘clean’’ Atlantic air from the SW to NW. In these conditions, the difference in O3 concentration observed at Mace Head and a rural site on the east coast of the UK indicates the net O3 production or loss within the UK boundary layer. A simple box model is then used to convert the concentration difference into a mass. The final budget shows that for most of the year the UK is a net sink for O3 (25 to 800 Gg-O3 month1) with production only exceeding losses in the photochemically active summer months (+45 Gg-O3 month1).

Photochemical ozone formation in north west Europe and its control Photochemical ozone formation in north west Europe and its control

Date added: 08/07/2003
Date modified: 07/23/2009
Filesize: 635.36 kB

DERWENT, R.G., Jenkin, M.E., Saunders, S.M., Pilling, M.J., Simmonds, P.G., Passant, N.R., Dollard, G.J., Dumitrean, P. and Kent, A., 2003: Photochemical ozone formation in north west Europe and its control. Atmos Environ, 37, 1,983-1,991.


Abstract


A photochemical trajectory model together with a Master Chemical Mechanism and a highly speciated emission inventory for organic compounds have been used to describe the formation of ozone in north west Europe and to identify the most prolific ozone-forming organic compounds. Observations are reviewed to assess the impact of emission controls on their urban volatile organic compound (VOC) concentration trends with time. The observed trends are then used to deduce the likely trends in episodic peak ozone concentrations and to compare them with observed trends in peak ozone concentrations. It is concluded that it is likely that motor vehicle emission controls have brought about a substantial reduction in episodic peak ozone concentrations in north west Europe during the 1990s.

 

Estimating European emissions of ozone-depleting and greenhouse gases using observations and a Estimating European emissions of ozone-depleting and greenhouse gases using observations and a

Date added: 08/07/2003
Date modified: 07/27/2009
Filesize: 1.48 MB

Manning, A. J., D. B. Ryall, R. G. Derwent, P. G. Simmonds, and S. O'Doherty (2003), Estimating European emissions of ozone-depleting and greenhouse gases using observations and a modeling back-attribution technique, J. Geophys. Res., 108(D14), 4405, doi:10.1029/2002JD002312.


Abstract


The Numerical Atmospheric Dispersion Modeling Environment (NAME) dispersion model driven by three-dimensional (3-D) synoptic meteorology from the Unified Model has been used to determine the fraction of air arriving at Mace Head, Ireland, from different European regions over a 6-year period. These data, along with observations of pollutants at Mace Head and a best fit algorithm, have been used to derive emission estimates over Western Europe. The algorithm starts from randomly generated emission maps and iterates toward the best solution. Using an idealized case study, it has been shown to be effective at distinguishing between distinct source regions. The technique has been applied to two ozone-depleting gases, CFC-11 and CFC-12, and two greenhouse gases, methane and nitrous oxide. The emissions derived compare favorably with existing inventories. The technique is able to provide information regarding the emission distribution across Europe and to estimate area and country contributions; information that for some species is not readily available by other means. It is a different methodology to those currently used and so is a useful tool in verifying existing inventories.

 

THE NAMBLEX FIELD Campaign 2002 THE NAMBLEX FIELD Campaign 2002

Date added: 08/07/2003
Date modified: 08/07/2008
Filesize: 5.06 kB
Heard, D.E.The NAMBLEX field campaign 2002 [EGU04-A-03242].

PRODUCTION OF METHANOL, ACETONE AND. ACETALDEHYDE DURING LONG-RANGE. TRANSPORT PRODUCTION OF METHANOL, ACETONE AND. ACETALDEHYDE DURING LONG-RANGE. TRANSPORT

Date added: 08/07/2003
Date modified: 08/07/2008
Filesize: 32.63 kB
Stanton, J.C.; Pilling, M.J.; Hopkins, J.R.; Lewis, A.C.Production of methanol, acetone and acetaldehyde during long-range transport [EGU04-A-07457].

Physical and chemical properties of aerosol during the North Atlantic Marine Boundary Layer Exp Physical and chemical properties of aerosol during the North Atlantic Marine Boundary Layer Exp

Date added: 08/07/2003
Date modified: 07/27/2009
Filesize: 32.66 kB
Coe, H.; THE NAMBLEX AEROSOL TEAM Physical and chemical properties of aerosol during the North Atlantic Marine Boundary Layer EXperiment (NAMBLEX) [EGU04-A-03236].
Abstract

 

A wide range of particle physical and chemical measurements were made at Mace Head on the Atlantic coast during the North Atlantic Marine Boundary Layer EXperiment during August 2002. The measurements included particle number, and size distribution from 10 nm to 20 um diameter. These data will be used to show how the loss rates of gaseous species with different uptake coefficients to aerosol impacts on the lifetime of species in the MBL and indicates the extent to which aerosol are an effective sink for a range of species. An Aerodyne Aerosol Mass Spectrometer was used to make continuous measurements of sulphate, nitrate and organic mass loading in the submicron size range at high time resolution. These data are compared with the analyses of filters from multi stage impactor sample collections. The air masses sampled during the experiment are characterised in terms of the aerosol physics and chemistry and comparisons between the AMS and the impactor samples will be shown.Westerly winds provide near background concentrations but significant loadings were observed in several air masses. Gas phase VOC data will be used as a guide to the photochemical age of the air and this will be compared with the aerosol components measured by the AMS. Correlations between gas phase oxidised VOC and the organic aerosol loading will be shown.

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