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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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Airborne concentrations and deposition fluxes of major and trace species at marine stations in Airborne concentrations and deposition fluxes of major and trace species at marine stations in

Date added: 08/05/1997
Date modified: 06/30/2009
Filesize: 1.36 MB

Foltescu et al (1996). V.L. Foltescu, E. Selin Lindgren, J. Isakson, M. Oblad, R. Tiede, J. Sommar, J.M. Pacyna and K. Toerseth , Airborne concentrations and deposition fluxes of major and trace species at marine stations in southern Scandinavia. Atmospheric Environment 30 22 (1996), pp. 3857–3872.


Abstract


Extensive measurements of airborne concentrations and deposition fluxes of many major and trace species were performed within the framework of the BMCAPE project (Background Maritime Contribution to Atmospheric Pollution in Europe) at two Scandinavian sites (Saby in Sweden and Lista in Norway) during four seasons in 1993 and 1994. The study focused on gaseous and particulate S-, N- and CI-species.Airborne concentration levels during the different campaigns, seasons and the various air masses encountered are presented for the following gaseous and particulate species: SO2, HCl, NOx, HNO3, NH3, SO2-4, NH+4, NO-3, S, Cl, K, Ca, V, Ni, Zn, Br, Pb and condensation nuclei. In addition, particle concentrations of Ti, Fe, Cu and Mn are discussed in the text. A time series is given for particulate and gaseous Hg. Annual flux estimates for Southern Scandinavia are given for Mn, Fe, Ni, Cu, Zn, Pb, Cl, S, non-sea-salt-sulphate-S, As, Na, K, Ca, Mg, NO-3-N and NH+4-N. Based on direct flux measurements to a water surface, dry deposition velocities are determined for nine elements: Mn, Fe, Ni, Cu, Zn, Pb, Cl, S, Ca.

 

Airborne measurements of nucleation mode particles I coastal nucleation and growth rates Airborne measurements of nucleation mode particles I coastal nucleation and growth rates

Date added: 08/01/2006
Date modified: 06/30/2009
Filesize: 1.47 MB

O’Dowd, C.D, Y. J. Yoon, W. Junkerman, P. P. Aalto, and H. Lihavainen, Airborne Measurements of Nucleation Mode Particles I: Coastal Atlantic Nucleation Events. Atmos. Chem. Phys. Discuss, 6, 8097-8123, 2006.


Abstract


A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs) (50% cut from 3–5.4–9.6 nm) and a nano-Scanning Mobility Particle Sizer (nSMPS) and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km) growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

Airborne trace gas measurements over open ocean and coastal regions upwind of Mace Head, Irelan Airborne trace gas measurements over open ocean and coastal regions upwind of Mace Head, Irelan

Date added: 08/06/2003
Date modified: 07/27/2009
Filesize: 13.7 kB

Ruth Purvis, Ally Lewis, Jim McQuaid, "Airborne Trace Gas Measurements Over Open Ocean and Coastal Regions Upwind of Mace Head, Ireland", Geophysical Research Abstracts Volume 5, 2003.


Abstract

 

The spatial distribution of a number of trace species has been determined in marine boundary layer (MBL) and free troposphere (FT) air around the Mace Head Atmospheric Research Station, Ireland. CO and ozone measurements were made onboard NERC Dornier 228-101 research aircraft operated by the Airborne Remote Sensing Facility during the SNAP (Supporting NAMBLEX from an Airborne Platform) campaign in August 2002. High frequency whole air sampling from the aircraft with ground analysis using GC-FID was used for C2 - C6 hydrocarbons mixing ratios. The campaign was conducted in conjunction with the ground based NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign carried out at Mace Head. The distribution of trace species was investigated in both coastal regions and above the deep waters beyond the continental shelf. A vertical gradient in concentration of hydrocarbonand sulphur species with known oceanic sources was observed in the MBL over both oceanic regions when compared to anthropogenic tracers such as acetylene and CO. Under clear sky conditions typical maximum mixing ratios were MBL ethene 78 pptV: FT ethene 10 pptV: MBL DMS: 89 pptV: FT DMS 21 pptV. Elevated mixing ratios of species with oceanic origin were observed in the lower most FT in regions experiencing strong convective activity associated with cumulus cells. Vertical profiles centred over the field sit showed good agreement between ground based and airbornehydrocarbon measurements taken within the MBL. The MBL upwind of Mace Head appeared well mixed with respect to both NMHCs, CO and ozone. Above 2 km showed distinct layers with free tropospheric ozone values of 50 ppbV contrasting typical MBL values of less than 30 ppbV. Flights indicate aboundary layer height of approximately 1200 m. The observations confirm that for these species the surface site measurements are generally representative of the marine boundary layer as a whole but not of the air mass above.

Aircraft Measurements During NAMBLEX (the SNAP campaign) Aircraft Measurements During NAMBLEX (the SNAP campaign)

Date added: 08/06/2003
Date modified: 07/27/2009
Filesize: 33.65 kB
Purvis R.M., Lewis A.C., McQuaid J.B. & Lee J.D. "Aircraft Measurements During NAMBLEX (the SNAP campaign)." Geophys Res. Abs. 6 (2004):

Abstract

 

The spatial distribution of a number of trace species has been determined in marine boundary layer (MBL) and free troposphere (FT) air around the Mace Head Atmospheric Research Station, Ireland. CO and ozone measurements were made onboard the NERC Dornier 228-101 research aircraft operated by the Airborne Remote Sensing Facility during the SNAP (Supporting NAMBLEX from an Airborne Platform) campaign in August 2002. High frequency whole air samples taken from onboard the aircraft with ground analysis using GC-FID were used for C2 - C6 hydrocarbons mixing ratios. The campaign was conducted in conjunction with the ground based NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign carried out at Mace Head during the summer of 2002. The distribution of trace species was investigated in both coastal regions and above the deep waters beyond the continental shelf. A vertical gradient in concentration of hydrocarbon and sulphur species with known oceanic sources was observed in the MBL over both oceanic regions when compared to anthropogenic tracers such as acetylene and CO. Under clear sky conditions typical maximum mixing ratios were MBL ethene 78 pptV: FT ethene 10 pptV: MBL DMS: 89 pptV: FT DMS 21 pptV.

Elevated mixing ratios of species with oceanic origin were observed in the lower most  FT in regions experiencing strong convective activity associated with cumulus cells. Vertical profiles centred over the field site showed good agreement between ground based and airborne hydrocarbon measurements taken within the MBL. The MBL upwind of Mace Head appeared well mixed with respect to both NMHCs,CO and ozone. Above 2 km showed distinct layers with free  tropospheric ozone values of 50 ppbV contrasting typical MBL values of less than 30 ppbV. Flights indicate a boundary layer height of approximately 1200 m. The observations confirm that for these species the surface site measurements are generally representative of the marine boundary layer as a whole but not of the air mass above.

Aitken Nuclei Measurements and Evidence of Gas-to-particle conversion Processes at Mace Head, Ireland.. Aitken Nuclei Measurements and Evidence of Gas-to-particle conversion Processes at Mace Head, Ireland..

Date added: 08/26/1994
Date modified: 07/23/2009
Filesize: 840.25 kB

O'Connor, T.C., McGovern, F.M., Jennings, S.G. & Philipp, C.(University of Hannover)  (1994)-
Aitken nuclei measurements and evidence of gas-to-particle conversion processes at Mace Head, Ireland. Proceedings of  EUROTRAC 94 Symposium, The Hague, SPB Academic Publishing, 1206-1209.


An analysis of condensation nuclei levels at Mace Head, Ireland An analysis of condensation nuclei levels at Mace Head, Ireland

Date added: 07/31/1999
Date modified: 07/27/2009
Filesize: 737.83 kB

Mc Govern, F.M. (1999). An analysis of condensation nuclei levels at Mace Head, Ireland. Atmos. Environ., 33, 1711-1723.


Abstract


Condensation nuclei (CN) concentrations measured at Mace Head between 1990 and 1992 are presented. The background CN concentration was found to typically range from 100 to 700 cm-3. Concentration values were in this range for 55% of the measurement period. No seasonal cycle was observed in the CN concentration values. Concurrent equivalent black carbon (EBC) measurements are used to examine anthropogenic influences on the background CN concentration. Evidence that transatlantic air mass transport influenced the background CN concentration contributing to increased CN and EBC levels, is shown. During polluted conditions the CN concentration was generally higher than 1000 cm-3. The principal source for high pollution levels was European air masses arriving at the site. Very high CN concentrations, greater than 50 000 cm-3, are attributed to local gas-to-particle conversion processes. The characteristics of a number of particle production events are considered. These show that these events are highly photochemical and occur during both clean and polluted conditions. Such production events though infrequent contributed significantly to the total aerosol number concentration.

An analysis of rapid increases in condensation nuclei concentrations at a remote coastal site i An analysis of rapid increases in condensation nuclei concentrations at a remote coastal site i

Date added: 08/06/1999
Date modified: 07/27/2009
Filesize: 885.01 kB

Grenfell, J.L., R.M. Harrison, A.G. Allen, J.P. Shi, S.A. Penkett, C.D. O'Dowd, M.H. Smith, M.K. Hill, L. Robertson, C.N. Hewitt, B. Davison, A.C. Lewis, D.J. Creasey, D.E. Heard, K. Hebestreit, B. Alicke and J. James, An analysis of rapid increases in condensation nuclei concentrations at a remote site on the West Irish Coast, J. Geophys.Res., 104, 13,771-13,780, 1999, (Ser. No. ACP073).


Abstract


Massive bursts in condensation nuclei (CN) concentration were recorded at a remote site on the west Irish coast during campaigns in summer 1996 and spring/summer 1997. Number concentrations of 3-7 nm diameter CN were observed to rise daily from 102-103 up to ∼105 /cm3 for 1-3 hours. Data were collected as part of the Atmospheric Chemistry Studies in the Oceanic Environment program. In a previous paper the burst phenomenon was linked to the movement of the tide, and it was suggested that enhanced biogenic emissions occurred near low tide with concomitant rapid homogeneous gas phase CN formation. In this paper possible chemical mechanisms for the burst phenomenon are investigated. Two approaches are adopted. First, by assuming a 20:80 sulfate:water molar composition and calculating the number distribution using data from condensation particle counters, the total mass of CN formed during a burst is evaluated. This is compared with that mass of sulfate produced by OH-initiated dimethyl sulfide (DMS) oxidation. The procedure is termed mass balance. Second, a variety of chemical species are coplotted with tidal height. DMS oxidation is not believed to play a major role in CN formation at this site because (1) the mass balance calculations imply ambient DMS concentrations higher than those observed, and (2) gas phase HCI, HNO3. SO2, and NH3 did not exhibit any discernible correlation with tidal height. Further, none of the suite of observed nonmethane hydrocarbons or DMS showed a tidal relation. No mechanism has to date been convincingly identified for the burst phenomenon.

 

An assessment of the surface ozone trend in Ireland relevant to air pollution and environmental protection An assessment of the surface ozone trend in Ireland relevant to air pollution and environmental protection

Date added: 03/12/2013
Date modified: 03/12/2013
Filesize: 442.05 kB

Tripathi, Om, P., Stephen G. Jennings, Colin O’Dowd, Barbara O’Leary, Keith Lambkin, Eoin Moran, Simon J. O’Doherty and T. Gerard Spain, An assessment of the surface ozone trend in Ireland relevant to air pollution and environmental protection, Atmos. Pollution Res., 3, 341-351, 2012.


Abstract. Hourly data (1994–2009) of surface ozone concentrations at eight monitoring sites have been investigated to assess target level and long–term objective exceedances and their trends. The European Union (EU) ozone target value for human health (60 ppb–maximum daily 8–hour running mean) has been exceeded for a number of years for almost all sites but never exceeded the set limit of 25 exceedances in one year. Second highest annual hourly and 4th highest annual 8–hourly mean ozone concentrations have shown a statistically significant negative trend for in–land sites of Cork–Glashaboy, Monaghan and Lough Navar and no significant trend for the Mace Head site. Peak afternoon ozone concentrations averaged over a three year period from 2007 to 2009 have been found to be lower than corresponding values over a three–year period from 1996 to 1998 for two sites: Cork–Glashaboy and Lough Navar sites. The EU long–term objective value of AOT40 (Accumulated Ozone Exposure over a threshold of 40 ppb) for protection of vegetation (3 ppm–hour, calculated from May to July) has been exceeded, on an individual year basis, for two sites: Mace Head and Valentia. The critical level for the protection of forest (10 ppm–hour from April to September) has not been exceeded for any site except at Valentia in the year 2003. AOT40–Vegetation shows a significant negative trend for a 3–year running average at Cork–Glashaboy (–0.13±0.02 ppm–hour per year), at Lough Navar (–0.05±0.02 ppm–hour per year) and at Monaghan (–0.03±0.03 ppm–hour per year–not statistically significant) sites. No statistically significant trend was observed for the coastal site of Mace head. Overall, with the exception of the Mace Head and Monaghan sites, ozone measurementrecords at Irish sites show a downward negative trend in peak values that affect human health and vegetation.

 

An automated system for near-real time monitoring of trace atmospheric halocarbons An automated system for near-real time monitoring of trace atmospheric halocarbons

Date added: 08/05/1998
Date modified: 07/27/2009
Filesize: 122.2 kB

An Automated System for Near-Real-Time Monitoring of Trace Atmospheric Halocarbons, Bassford, M.R., Simmonds, P.G., and Nickless, G.,Anal. Chem., 70, 5, 958 - 965, 1998,  10.1021/ac970861z


Abstract


A new gas chromatographic method developed to quantitatively determine important atmospheric halocarbons is described. Target compounds include replacement CFCs, chlorinated solvents, and biosynthesized (naturally produced) organohalogens, all trace gases in the atmosphere at concentrations ranging from 0.1 to 600 pptv (where pptv = 1 part in 10-12 by volume). A combination of ultralow concentrations and relatively small electron attachment cross sections renders these compounds very difficult to routinely measure in the background air typical of remote atmospheric monitoring stations. Detection is achieved by preconcentration of a 200-mL air sample using an adsorbent-filled microtrap and enhancement of electron capture detector response by oxygen doping one of two detectors connected in series. Oxygen doping specifically targets halocarbons with relatively poor electron attachment rate coefficients. The work described here details construction of a novel analytical system, laboratory trials, and optimization followed by an extended field campaign at a remote atmospheric monitoring station, Mace Head, Ireland. A calibration standard or ambient air sample was acquired every hour using a cyclic, automated procedure without employing cryogenic preconcentration or refocusing. Overall precision of the analytical method for the target compounds is between 0.3 and 1.5%.

 

An important source of marine secondary organic aerosol from biogenic amines, An important source of marine secondary organic aerosol from biogenic amines,

Date added: 04/08/2009
Date modified: 07/23/2009
Filesize: 548.79 kB

Facchini, M.C., S. Decesari, M. Rinaldi, C. Carbone, E. Finessi, M. Mircea, S. Fuzzi, F. Moretti, E. Tagliavini, D. Ceburnis and C. D. O’Dowd, An important source of marine secondary organic aerosol from biogenic amines, Env. Sci. & Tech., 10.1021/es8018385, 2008


Abstract

 

Relevant concentrations of dimethyl- and diethylammonium salts(DMA+andDEA+)weremeasured in submicrometer marine aerosol collected over the North Atlantic during periods of high biological activity (HBA) in clean air masses (median concentration (minimum-maximum))26 (6-56) ngm-3). Much lower concentrations were measured during periods of low biological activity (LBA): 1 (<0.4-20) ng m-3 and when polluted air masses were advected to the sampling site: 2 (<0.2-24) ngm-3.DMA+ andDEA+ are the most abundant organic species, second only to MSA, detected in fine marine particles representing on average 11% of the secondary organic aerosol (SOA)fraction and a dominant part (35% on average) of the watersoluble organic nitrogen (WSON). Several observations support the hypothesis that DMA+ and DEA+ have a biogenic oceanic source and are produced through the reaction of gaseous amines with sulfuric acid or acidic sulfates. Moreover, the water-soluble fraction of nascent marine aerosol particles produced by bubble-bursting experiments carried out in parallel to ambient aerosol sampling over the open ocean showed WSON, DMA+, and DEA+ concentrations always below the detection limit, thus excluding an important primary sea spray source.

 

An investigation of the behaviour of drops and drop-pairs subjected to strong electrical forces An investigation of the behaviour of drops and drop-pairs subjected to strong electrical forces

Date added: 09/12/1971
Date modified: 07/23/2009
Filesize: 703.62 kB

Brazier-Smith, P.R., Jennings, S.G., and Latham, J.  (1971)- An investigation of the behaviour of drops and drop-pairs subjected to strong electrical forces. Proc. Roy. Soc., A325, 363-376.


Abstract


A numerical model is described which simulates irrotational, incompressible flow on a computer. It has been applied to the problems of the deformation of uncharged drop-pairs separated in an electric field of critical strength and isolated drops charged to the Rayleigh limit in the absence of an electric field. In the case of pairs of drops of radius R, separated by an initial distance X in an electric field equal to that predicted by Brazier-Smith (1971) to cause disruption two types of interaction were identified. For values of X/R less than about 1.2 the drops deform and their surfaces accelerate towards each other and make contact. For X/R greater than about 1.2 the drops deform, a concavity appears at the near poles and then the near surfaces assume a conical profile of angle equal to that predicted by Taylor (1964). The subsequent issuance of liquid from these jets could not be studied with the present model. The computations predict that an isolated drop carrying the critical charge calculated by Rayleigh (1882) will deform, while retaining an approximately spheroidal shape, until the axial ratio achieves a value of about 2.5, whereupon cones possessing the Taylor angle are formed at each end of the drop, from which liquid will issue in the form of a jet. Experiments were performed in which uncharged water drops of radius R and surface tension T were directed towards a highly polished, earthed electrode at a shallow angle in an electric field of strength E. Each drop experienced the same electric forces as would result if the earthed electrode were removed and replaced by an identical drop twice as far away. Stroboscopic photographs of drops and their optical image in the polished electrode illustrated their deformation and eventual disintegration. The experimentally determined relation between normalized disintegration field E(R/T)1/4 and both X/R and the elongation a/b agreed well with theory over a wide range of separations.

An isotopic study of atmospheric sulphur at three sites in Wales and at Mace Head, Eire An isotopic study of atmospheric sulphur at three sites in Wales and at Mace Head, Eire

Date added: 08/06/1998
Date modified: 07/27/2009
Filesize: 1.36 MB
McArdle N. ; Liss P. ; Dennis P.  1998, An isotopic study of atmospheric sulphur at three sites in Wales and at Mace Head, Eire, J. Geophys. Res. Vol. 103 , No. D23 , p. 31,079 (98JD01664)

Abstract


Sulphur isotope measurements made on aerosol and precipitation samples collected at three sites in Wales and Mace Head, Eire, between March 1993 and 1994, had highest non-sea-salt sulphate δ34S values, up to 11.9‰ for aerosol and 9.7‰ for precipitation, during the summer months. Aerosol methanesulphonate shows a clear summer peak with values up to 3-4 nmol m-3. Assuming samples contained only sulphur from terrestrial/anthropogenic, sea salt, and marine biogenic (from the oxidation of dimethylsulphide) sources, we used the sulphur isotope values to determine the contribution of dimethylsulphide-derived sulphate to total sulphate. In general the biogenic contribution was small, < 10%, although in samples from marine air masses it was as high as 40%. A comparison of aerosol and precipitation δ34S values found no evidence for large isotopic fractionations during the oxidation of sulphur dioxide.

An overview of current issues in the uptake of atmospheric trace gases by aerosols and clouds An overview of current issues in the uptake of atmospheric trace gases by aerosols and clouds

Date added: 11/10/2010
Date modified: 11/10/2010
Filesize: 1.06 MB

Kolb, C. E., R. A. Cox, J. P. D. Abbatt, M. Ammann, E. J. Davis, D. J. Donaldson, B. C. Garrett, C. George, P. T. Griffiths, D. R. Hanson, M. Kulmala, G. McFiggans, U. Pöschl, I. Riipinen, M. J. Rossi, Y. Rudich, P. E. Wagner, P. M. Winkler, D. R. Worsnop, and C. D. O' Dowd, An overview of current issues in the uptake of atmospheric trace gases by aerosols and clouds, Atmos. Chem. Phys.10, 10561–10605, doi:10.5194/acp-10-10561-2010, 2010.


A workshop was held in the framework of the ACCENT (Atmospheric Composition Change – a European Network) Joint Research Programme on “Aerosols” and the Programme on “Access to Laboratory Data”. The aim of the workshop was to hold “Gordon Conference” type discussion covering accommodation and reactive uptake of water vapour and trace pollutant gases on condensed phase atmospheric materials. The scope was to review and define the current state of knowledge of accommodation coefficients for water vapour on water droplet and ice surfaces, and uptake of trace gas species on a variety of different surfaces characteristic of the atmospheric condensed phase particulate matter and cloud droplets. Twenty-six scientists participated in this meeting through presentations, discussions and the development of a consensus review.  In this review we present an analysis of the state of knowledge on the thermal and mass accommodation coefficient for  water vapour on aqueous droplets and ice and a survey of current state-of the-art of reactive uptake of trace gases on a range of liquid and solid atmospheric droplets and particles. The review recommends consistent definitions of the various parameters that are needed for quantitative representation of the range of  as/condensed surface kinetic processes important for the atmosphere and identifies topics that require  additional research.

An overview of the Lagrangian experiments undertaken during the NA regional ACE An overview of the Lagrangian experiments undertaken during the NA regional ACE

Date added: 08/06/2000
Date modified: 06/30/2009
Filesize: 1.51 MB

Johnson, D. W., S. R. Osborne, R. Wood, K. Suhre, M. O. Andrae, R. Johnson, S. Businger, P. K. Quinn, T. Bates, P. Durkee, H. Johnson, L. M. Russell, K. Noone, P. Glantz, B. Bandy, C. O'Dowd, S. Rapsomanikis and J. Rudolph. An overview of the Lagrangian experiments undertaken during the North Atlantic Regional Aerosol Characterisation Experiment (ACE - 2). Tellus, 52B, 290-320. 2000.


Abstract

 

One of the primary aims of the North Atlantic regional Aerosol Characterisation Experiment (ACE-2) was to quantify the physical and chemical processes affecting the evolution of the major aerosol types over the North Atlantic. The best, practical way of doing this is in a Lagrangian framework where a parcel of air is sampled over several tens of hours and its physical and chemical properties are intensively measured. During the intensive observational phase of ACE-2, between 15 June 1997 and 24 July 1997, 3 cloudy Lagrangian experiments and 3 cloud-free, Lagrangian experiments were undertaken between the south west tip of the Iberian Peninsula and the Canary Islands. This paper gives an overview of the aims and logistics of all of the Lagrangian experiments and compares and contrasts them to provide a framework for the more focused Lagrangian papers in this issue and future process modelling studies and parametrisation development. The characteristics of the cloudy Lagrangian experiments were remarkably different, enabling a wide range of different physical and chemical processes to be studied. In the 1st Lagrangian, a clean maritime air mass was sampled in which salt particle production, due to increased wind speed, dominated the change in the accumulation mode concentrations. In the 2nd Lagrangian, extensive cloud cover resulted in cloud processing of the aerosol in a polluted air mass, and entrainment of air from the free troposphere influenced the overall decrease in aerosol concentrations in the marine boundary layer (MBL). Very little change in aerosol characteristics was measured in the 3rd Lagrangian, where the pollution in the MBL was continually being topped up by entraining air from a residual continental boundary layer (CBL) above. From the analysis of all the Lagrangian experiments, it has been possible to formulate, and present here, a generalised description of a European continental outbreak of pollution over the sub-tropical North Atlantic.

 

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).

Analysis of PM2.5 particulate mass concentrations during 1999 at Mace Head Analysis of PM2.5 particulate mass concentrations during 1999 at Mace Head

Date added: 08/07/2000
Date modified: 07/27/2009
Filesize: 148.23 kB

Kleefeld S.; Jennings S.G., Analysis of PM2.5 particulate mass concentrations during 1999 at Mace Head, Journal of Aerosol Science, Volume 31, Supplement 1, September 2000 , pp. 731-732(2)


Abstract


In recent years, the quality of air we breathe has become a significant factor in the environment, with ncreasing interest in the properties of both indoor and outdoor air. Ambient air particles, in addition to gaseous species, are important components in the assessment of air quality, since there is increasing evidence for an association between adverse health effects and the levels of particulate air pollution. Especially the finer particle fraction PMz.5 (particulate mass concemrations with a 50% cut-off diameter of 2.5 pro) is able to penetrate deep into the respiratory system of humans and is best correlated with acute mortality and morbidity findings in urban areas (Oberd6rster et al., 1995). Few measurements of PM2.5 mass concentrations exist for urban areas (e.g. Chan et al., 1999, Chow et al., 1996), but no information is available so far for clean marine air concentrations in the North Atlantic region. Information on background concentrations of PM2.~ mass concentrations as well as on their sources is essential in the interpretation of urban particulate air pollution. Within this study PMz.~ mass concentrations are presented for a clean air site at the Atmospheric Research Station at Mace Head, Cama, (53019 ' N, 9054 ' W) on the west coast of Ireland for the year 1999, and a source identification is performed.

Applicability of condensation particle counters to measure atmospheric clusters Applicability of condensation particle counters to measure atmospheric clusters

Date added: 09/12/2008
Date modified: 07/10/2009
Filesize: 617.3 kB

Sipilä, M., Lehtipalo, K., Kulmala, M., Petäjä, T., Junninen, H., Aalto, P. P., Manninen, H. E., Kyrö, E.-M., Asmi, E., Riipinen, I., Curtius, J., Kürten, A., Borrmann, S., and O'Dowd, C. D.: Applicability of condensation particle counters to measure atmospheric clusters, Atmos. Chem. Phys., 8, 4049-4060, 2008


Abstract


This study presents an evaluation of a pulse height condensation particle counter (PH-CPC) and an expansion
condensation particle counter (E-CPC) in terms of measuring ambient and laboratory-generated molecular and ion clusters. Ambient molecular cluster concentrations were measured with both instruments as they were deployed in conjunction with an ion spectrometer and other aerosol instruments in Hyyti¨al¨a, Finland at the SMEAR II station between 1 March and 30 June 2007. The observed cluster concentrations varied and ranged from some thousands to 100 000 cm−3. Both instruments showed similar (within a factor of 5) concentrations. An average size of the detected clusters was approximately 1.8 nm. As the atmospheric measurement of sub 2-nm particles and molecular clusters is a challenging task, we conclude that most likely we were unable to detect the smallest clusters. Nevertheless, the reported concentrations are the best estimates to date for minimum cluster concentrations in a boreal forest environment.

Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO

Date added: 08/06/2003
Date modified: 07/27/2009
Filesize: 184.19 kB
W. J. Bloss, T. J. Gravestock, D. E. Heard, T. Ingham,G. P. Johnson and J. D. Lee, "Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO2, NO and IO by laser-induced fluorescence", Journal of Environmental Monitoring., 5, 21-28 (2003).

Abstract

 

A tuneable, high pulse-repetition-frequency, solid state Nd:YAG pumped titanium sapphire laser capable of generating radiation for the detection of OH, HO2, NO and IO radicals in the atmosphere by laser induced fluorescence (LIF) has been developed. The integration of the laser system operating at 308 nm into a field measurement apparatus for the simultaneous detection of hydroxyl and hydroperoxy radicals is described, with detection limits of 3.1 6 105 molecule cm23 (0.012 pptv in the boundary layer) and 2.6 6 106 molecule cm23 (0.09 pptv) achieved for OH and HO2 respectively (30 s signal integration, 30 s background integration, signalto- noise ratio ~ 1). The system has been field tested and offers several advantages over copper vapour laser pumped dye laser systems for the detection of atmospheric OH and HO2 radicals by LIF, with benefits of greater tuning range and ease of use coupled with reduced power consumption, instrument footprint and warm-up time. NO has been detected in the atmosphere at y 1 ppbv by single photon LIF using the A 2S1 B X 2P1/2 (0,0) transition at 226 nm, with absolute concentrations in good agreement with simultaneous measurements made using a chemiluminescence analyser. With some improvements in performance, particularly with regard to laser power, the theoretical detection limit for NO is projected to be y 2 6 106 molecule cm23 (0.08 pptv). Whilst operating at 445 nm, the laser system has been used to readily detect the IO radical in the laboratory, and although it is difficult to project the sensitivity in the field, an estimate of the detection limit is v 1 6 105 molecule cm23 (v 0.004 pptv), well below previously measured atmospheric concentrations of IO.

Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO

Date added: 08/06/2003
Date modified: 06/30/2009
Filesize: 184.19 kB
W. J. Bloss, T. J. Gravestock, D. E. Heard, T. Ingham,G. P. Johnson and J. D. Lee, "Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO2, NO and IO by laser-induced fluorescence", Journal of Environmental Monitoring., 5, 21-28 (2003).

Abstract


A tuneable, high pulse-repetition-frequency, solid state Nd:YAG pumped titanium sapphire laser capable of generating radiation for the detection of OH, HO2, NO and IO radicals in the atmosphere by laser induced fluorescence (LIF) has been developed. The integration of the laser system operating at 308 nm into a field measurement apparatus for the simultaneous detection of hydroxyl and hydroperoxy radicals is described, with detection limits of 3.1 6 105 molecule cm23 (0.012 pptv in the boundary layer) and 2.6 6 106 molecule cm23 (0.09 pptv) achieved for OH and HO2 respectively (30 s signal integration, 30 s background integration, signalto- noise ratio ~ 1). The system has been field tested and offers several advantages over copper vapour laser pumped dye laser systems for the detection of atmospheric OH and HO2 radicals by LIF, with benefits of greater tuning range and ease of use coupled with reduced power consumption, instrument footprint and warm-up time. NO has been detected in the atmosphere at y 1 ppbv by single photon LIF using the A 2S1 B X 2P1/2 (0,0) transition at 226 nm, with absolute concentrations in good agreement with simultaneous measurements made using a chemiluminescence analyser. With some improvements in performance, particularly with regard to laser power, the theoretical detection limit for NO is projected to be y 2 6 106 molecule cm23 (0.08 pptv). Whilst operating at 445 nm, the laser system has been used to readily detect the IO radical in the laboratory, and although it is difficult to project the sensitivity in the field, an estimate of the detection limit is v 1 6 105 molecule cm23 (v 0.004 pptv), well below previously measured atmospheric concentrations of IO.

Assessment of changing meteorology and emissions on air quality using a regional climate model: Impact on ozone Assessment of changing meteorology and emissions on air quality using a regional climate model: Impact on ozone

Date added: 03/12/2013
Date modified: 03/12/2013
Filesize: 3.64 MB

Coleman, L. , D. Martin, S. Varghese, S.G. Jennings, C.D. O’Dowd, Assessment of changing meteorology and emissions on air quality using a regional climate model: Impact on ozone, Atmos. Environ., http://dx.doi.org/10.1016/j.atmosenv.2012.11.048, 2012


 

Abstract. A regional climate model is used to assess changes in atmospheric ozone for the years 2030, 2050 and 2100 relative to 2006 brought about by changes in meteorology and emissions. The simulations are evaluated against ozone measurements for 2006, exhibiting good agreement between the model-predicted measurements and the measured annual cycles. Under the RCP6 emission scenario used in these simulations, average ozone mixing ratios are set to reduce by 2.0 ppb over domains encompassing Europe and the North East Atlantic between 2006 and 2100 with the most significant decrease occurring after 2050 due to the pattern in changing emissions. Peak reductions of more than 8 ppb are observed during summer time over mainland Europe by 2100. Model output was studied for three relevant subdomains, namely the North East Atlantic, Ireland and Europe. The relative contribution of changes in both emissions and meteorology is assessed. Over the whole domain, changing emissions are predominantly responsible for changes in surface ozone; although over the North East Atlantic domain, the changing emissions do not perturb surface ozone trends and the decrease in 2100 levels is entirely attributable to changing meteorology.

Atmospheric aerosol measurements at Mace Head, Ireland Atmospheric aerosol measurements at Mace Head, Ireland

Date added: 08/07/2000
Date modified: 07/27/2009
Filesize: 247.74 kB
Jennings S.G., Atmospheric aerosol measurements at Mace Head, Ireland,Journal of Aerosol Science, Volume 31, Supplement 1, September 2000 , pp. 580-583(4)

Abstract


The atmospheric aerosol plays a fundamental role in the earth's atmosphere, involving solid particulate material. Interest in atmospheric aerosol research has increased dramatically in recent years, as evidenced by a rapidly increasing publication rate in the discipline and through an accelerating presence in both national and international conference media. In earlier decades, interest in atmospheric aerosols was mainly because of their effects on visibility. More recently the accelerated interest in aerosols is largely due to their role in climate effects and in atmospheric chemistry processes. This has also been recognised internationally through activities, such as for example the International Global Atmospheric Chemistry (IGAC) Focus on aerosols and the World Meteorological Organisation (WMO), Global Atmospheric Watch (GAW) Aerosol, (WMO, 1997).

One of the largest uncertainties associated with climate forcing relates to the atmospheric aerosol, as noted by the Inter-Governmental Panel on Climate Change (IPCC); Houghton et al., 1995. The atmospheric aerosol shows large variability both in time and in space (Dreiling and Jaenicke, 1994) and is one of the major outstanding uncertainties in atmospheric aerosol research. Recently, there have been increasing studies of the natural aerosol since it is recognised that until natural background aerosol sources are better quantified, the influence of the more pollutant anthropogenic aerosol on climate for example, cannot be fully understood. The Mace Head Atmospheric Research Station has provided a good platform for the performance of a range of atmospheric aerosol studies some of which are summarised in the following pages.

Atmospheric bromoform at Mace Head, Ireland seasonality and evidence for a peatland source Atmospheric bromoform at Mace Head, Ireland seasonality and evidence for a peatland source

Date added: 08/07/2005
Date modified: 07/27/2009
Filesize: 692.16 kB

Carpenter, L. J., Wevill, D. J., O'Doherty, S., Spain, G., and Simmonds, P. G.: Atmospheric bromoform at Mace Head, Ireland: seasonality and evidence for a peatland source, Atmos. Chem. Phys., 5, 2927-2934, 2005.


Abstract


In situ atmospheric observations of bromoform (CHBr3) made over a 2.5 year period at Mace Head, Ireland from May 2001- Dec 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March - mid October) and 1.8+0.8 pptv (December-February). This indicates that, unlike CHCl3, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr3 have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr3 budget. Sharp increases in CHCl3 and CHBr3 concentrations and decreases in O3 concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms-1. These observations infer a shallow atmospheric boundary layer with increased O3 deposition and concentration of local emissions of both CHCl3 and CHBr3. The ratio of ΔCHCl3/ΔCHBr3 varied strongly according to the prevailing wind direction; from 0.60+0.15 in south-easterly (100-170° and northerly (340-20°) air to 2.5+0.4 in north-easterly (40-70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however had an immediate fetch inland, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl3 under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr3. We use correlations between CHCl3 and CHBr3 during the north-easterly land breeze events in conjunction with previous estimates of local wetland CHCl3 release to tentatively deduce a global wetland CHBr3 source of 20.4(0.4-948) Gg yr-1, which is approximately 7% of the total global source.

Atmospheric carbon dioxide and its stable isotope ratios, methane, carbon monoxide, nitrous oxi Atmospheric carbon dioxide and its stable isotope ratios, methane, carbon monoxide, nitrous oxi

Date added: 08/07/1998
Date modified: 07/27/2009
Filesize: 655.24 kB

Francey, R.J., L.P. Steele, R.L. Langenfelds, C.E. Allison, L.N. Cooper, B.L. Dunse, B.G. Bell, T.D. Murray, H.S. Tait, L. Thompson and K.A. Masarie, Atmospheric carbon dioxide and its stable isotope ratios, methane, carbon monoxide and hydrogen from Shetland Isles, Atmos. Environ., Vol. 32, No. 19, 3331-3338, 1998.


Abstract


Since November 1992, 0.5l glass flasks have been filled approximately monthly with dry marine air from Shetland Isles, Scotland (60.2oN, 1.2oW) and transported to CSIRO, Australia for analyses. The Shetland site is part of a CSIRO global flask network with 10-12 sites, anchored to continuous high precision in situ measurements made at the Australian Cape Grim Baseline Station (40.7oS, 144.7oE), a primary station in the Global Atmosphere Watch programme (GAW) coordinated by the World Meteorological Organisation. The methodology is summarised, and Shetland results for CO2, CH4, N2O, CO, H2 and delta13C, delta18O of CO2 presented for the period 1992-1996. We compare data to available results from surrounding stations of the NOAA cooperative network (in particular Mace Head, Ireland, 53.3oN, 9.9oW), and address issues of both trace species intercalibration and atmospheric spatial gradients. While considerable uniformity of trace-gas composition is evident in oceanic air over a 13o range of latitude, nevertheless anomalies in CO2 concentration and isotopic composition are suggested in samples representing air to the west of Shetland. The potential for remotely monitoring integrated emissions from northern Europe is also identified.

 

Atmospheric CO2 concentration variations recorded at Mace Head, Ireland, from 1992 to 1994 Atmospheric CO2 concentration variations recorded at Mace Head, Ireland, from 1992 to 1994

Date added: 07/31/1997
Date modified: 07/27/2009
Filesize: 491.17 kB

Bousquet, P., Gaudry. A., Ciais, P., Kazan, V., Monfray, P., Simmonds, P.G., Jennings, S.G., and O'Connor, T.C. (1997). Atmospheric CO2 concentration variations recorded at Mace Head, Ireland from 1992 to 1994. Phys. Chem. Earth, 21, 447-481.


Abstract


Atmospheric CO 2 has been monitored continuously at the Irish station of Mace-Head (MHD) since July 1992. The mean rate of increase is 1.85 ppmv yr -t with a peak-to-peak amplitude of 15.1+1.1 ppmv. The record also shows important short-term variations from the smoothed curve due to both European and oceanic influences and amplified by day/night local effects. Two different baseline conditions are defined in order to remove local perturbations. Restricted Baseline Conditions (RBC) keep data only representing atmospheric background conditions from the West. Extended Baseline Conditions (EBC) add stable air masses coming from all angular sectors to RBC selection. The contrast between western and eastern air masses coming respectively from North-Atlantic ocean and Europe is studied. For air masses arriving from the West, a systematic depletion in 1992-93 is found relative to all surrounding stations within the North- Atlantic basin. The partition of this depletion between European biospheric uptake and the North-Atlantic ocean cannot be performed as long as other tracers are not sampled regularly, or during intensive campaigns at Mace Head (13C/12C, Radon-222 and O2/N2). In contrast, Eastern air masses present strong positive anomalies in CO2 that reflect European sources.

Atmospheric Composition Change – Global and Regional Air Quality Atmospheric Composition Change – Global and Regional Air Quality

Date added: 11/11/2009
Date modified: 11/11/2009
Filesize: 9.8 MB

Monks, P.S., C. Granier, S. Fuzzi, A. Stohl, M. Williams, H. Akimoto, M. Amman, A. Baklanov, U. Baltensperger, I. Bey, N. Blake, R.S. Blake, K. Carslaw, O.R. Cooper, F. Dentener, D. Fowler, E. Fragkou, G. Frost, S. Generoso, P. Ginoux, V. Grewe, A. Guenther, H.C. Hansson, S. Henne, J. Hjorth, A. Hofzumahaus, H. Huntrieser, I.S.A. Isaksen, M.E. Jenkin, J. Kaiser, M. Kanakidou, Z. Klimont, M. Kulmala, P. Laj, M.G. Lawrence, J.D. Lee, C. Liousse, M. Maione, G. McFiggans, A. Metzger, A. Mieville, N. Moussiopoulos, J.J. Orlando, C. O'Dowd, P.I. Palmer, D.D. Parrish, A. Petzold, U. Platt, U. Poeschl, A.S.H. Prévôt, C.E. Reeves, S. Reimann, Y. Rudich, K. Sellegri, R. Steinbrecher, D. Simpson, H. ten Brink, J. Theloke, G.R. van der Werf, R. Vautard, V. Vestreng, Ch. Vlachokostas and R. vonGlasow, Atmospheric Composition Change – Global and Regional Air Quality, Atmos. Environ.,  doi:10.1016/j.atmosenv.2009.08.021  , 2009


Abstract.

Air quality transcends all scales with in the atmosphere from the local to the global with handovers and feedbacks at each scale interaction. Air quality has manifold effects on health, ecosystems, heritage and climate. In this review the state of scientific understanding in relation to global and regional air quality is outlined. The review discusses air quality, in terms of emissions, processing and transport of trace gases and aerosols. New insights into the characterization of both natural and anthropogenic emissions are reviewed looking at both natural (e.g. dust and lightning) as well as plant emissions. Trends in anthropogenic emissions both by region and globally are discussed as well as biomass burning emissions. In terms of chemical processing the major air quality elements of ozone, non-methane hydrocarbons, nitrogen oxides and aerosols are covered. A number of topics are presented as a way of integrating the process view into the atmospheric context; these include the atmospheric oxidation efficiency, halogen and HOx chemistry, nighttime chemistry, tropical chemistry, heat waves, megacities, biomass burning and the regional hot spot of the Mediterranean. New findings with respect to the transport of pollutants across the scales are discussed, in particular the move to quantify the impact of long-range transport on regional air quality. Gaps and research questions that remain intractable are identified. The review concludes with a focus of research and policy questions for the coming decade. In particular, the policy challenges for concerted air quality and climate change policy (co-benefit) are discussed.

Atmospheric Composition Change: Ecosystems - Atmosphere interactions Atmospheric Composition Change: Ecosystems - Atmosphere interactions

Date added: 11/11/2009
Date modified: 11/11/2009
Filesize: 7.78 MB

Fowler, D., K. Pilegaard, M.A. Sutton, P. Ambus, M. Raivonen, J. Duyzer, D. Simpson, H. Fagerli, S. Fuzzi, J.K. Schjoerring, C. Granier, A. Neftel, I.S.A. Isaksen, P. Laj, M.Maione, P.S. Monks, J. Burkhardt, U. Daemmgen, J. Neirynck, E. Personne, R. Wichink-Kruit, K. Butterbach-Bahl, C. Flechard, J.P. Tuovinen, M. Coyle, G. Gerosa, B. Loubet, N. Altimir, L. Gruenhage, C. Ammann, S. Cieslik, E. Paoletti, T.N. Mikkelsen, H. Ro-Poulsen, P. Cellier, J.N. Cape, L. Horváth, F. Loreto, Ü. Niinemets, P. I. Palmer, J.Rinne, P. Misztal, E. Nemitz, D. Nilsson, S. Pryor, M.W. Gallagher, T. Vesala, U. Skiba, N. Brüeggemann, S. Zechmeister-Boltenstern, J. Williams, C. O’Dowd, M. C. Facchini, G. de Leeuw, A. Flossman, N. Chaumerliac, J.W. Erisman, Atmospheric Composition Change: Ecosystems - Atmosphere interactions, Atmos. Environ., doi:10.1016/j.atmosenv.2009.07.068,  2009


Abstract.

Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth’s surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O3, CH4, N2O and particles in the size range 1 nm–10 mmincluding organic and inorganic chemical species. The main focus of the reviewis on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean–atmosphere exchange are included. The material presented is biased towards the last decade, but includes earlier work, where more recent developments are limited or absent.  New methodologies and instrumentation have enabled, if not driven technical advances in measurement. These developments have advanced the process understanding and upscaling of fluxes, especially for particles, VOC and NH3. Examples of these applications include mass spectrometric methods, such as  Aerosol Mass Spectrometry (AMS) adapted for field measurement of atmosphere–surface fluxes using micrometeorological methods for chemically resolved aerosols. Also briefly described are some advances in theory and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using aircraft and satellite remote sensing. The application of a flux-based approach in assessment of O3 effects on vegetation at regional scales is an important policy linked development secured through improved quantification of fluxes. The coupling of monitoring, modelling and intensive flux measurement at a continental scale within the NitroEurope network represents a quantum development in the application of research teams to address the underpinning science of reactive nitrogen in the cycling between ecosystems and the atmosphere in Europe. Some important developments of the science have been applied to assist in addressing policy questions, which have been the main driver of the research agenda, while other developments in understanding have not been applied to their wider field especially in chemistry-transport models through deficiencies in obtaining appropriate data to enable application or inertia within the modelling community. The paper identifies applications, gaps and research questions that have remained intractable at least since 2000 within the specialized sections of the paper, and where possible these have been focussed on research questions for the coming decade.

 

 

Atmospheric Emissions and Trends of Nitrous Oxide Deduced From 10 Years of ALE–GAGE Data Atmospheric Emissions and Trends of Nitrous Oxide Deduced From 10 Years of ALE–GAGE Data

Date added: 08/01/1990
Date modified: 07/27/2009
Filesize: 1.5 MB

R.G. Prinn, D. Cunnold, R. Rasmussen, P. Simmonds, F. Alyea, A. Crawford, P. Fraser, and R. Rosen.  Atmospheric emissions and trends of nitrous oxide deduced from ten years of ALE/GAGE data. J. Geophys. Res., 95, 18369-18385, 1990.


Abstract


We present and interpret long-term measurements of the chemically and radiatively important trace gas nitrous oxide (N2O) obtained during the Atmospheric Lifetime Experiment (ALE) and its successor the Global Atmospheric Gasses Experiment (GAGE). The ALE/GAGE data for N2O comprise over 110,000 individual calibrated real-time air analyses carried out over a 10-year (July 1978-June 1988) time period. These measurements indicate that the average concentration in the northern hemisphere is persistently 0.75+/-0.16 ppbv higher than in the southern hemisphere and that the global average linear trend in N2O lies in the range from 0.25 to 0.31% yr-1, with the latter result contingent on certain assumptions about the long-term stability of the calibration gases used in the experiment. Interpretation of the data, using inverse theory and a 9-box (grid) model of the global atmosphere, indicates that the N2O surface emissions into the 90°N-30°N, 30°N-0°, 0°-30°S, and 30°S-90°S semihemispheres account for about 22-34, 32-39, 20-29 and 11-15% of the global total emissions, respectively.<p>The measured trends and latitudinal distributions are consistent with the hypothesis that stratospheric photodissociation is the major atmospheric sink for N2O, but they do not support the hypothesis that the temporal N2O increase is caused solely by increases in anthropogenic N2O emissions associated with fossil fuel combustion. Instead, the cause for the N2O trend appears to be a combination of a growing tropical source (probably resulting from tropical land disturbance) and a growing northern mid-latitude source (probably resulting from a combination of fertilizer use and fossil fuel combustion). The exact combination of these sources which best fits the data depends on the assumed tropospheric-stratospheric exchange rates for N2O in the northern hemisphere relative to the southern hemisphere. Accepting a theoretically-calculated N2O lifetime of 166+/-16 years due to stratospheric destruction only, we deduce from the ALE/GAGE data a 10-year average global N2O emission rate of (20.5+/-2.4)×1012gN2O yr-1, but with significant year-to-year variations in emissions associated perhaps with year-to-year variations in tropical land disturbance.

Atmospheric histories of halocarbons from analysis of Antarctic firn air Major Montreal Protocol species Atmospheric histories of halocarbons from analysis of Antarctic firn air Major Montreal Protocol species

Date added: 08/01/2002
Date modified: 06/30/2009
Filesize: 832.27 kB
Sturrock, G. A., D. M. Etheridge, C. M. Trudinger, P. J. Fraser, and A. M. Smith (2002), Atmospheric histories of halocarbons from analysis of Antarctic firn air: Major Montreal Protocol species, J. Geophys. Res., 107(D24), 4765, doi:10.1029/2002JD002548.
Abstract

 

Air samples extracted from Antarctic firn at Law Dome have been analyzed for the suite of halocarbons that contribute most of the anthropogenic chlorine and about half the anthropogenic bromine presently released into the stratosphere. The species, all included in the Montreal Protocol, are the chlorofluorocarbons (CFCs -11, -12, -113, -114, -115), hydrochlorofluorocarbons (HCFCs -22, -141b, -142b), halons (H -1211, -1301), CH3CCl3 (methyl chloroform) and CCl4 (carbon tetrachloride). The measurements were used to reconstruct the atmospheric history of these species since the 1930s, providing a record considerably predating existing in situ records or other conventional air archives, encompassing virtually the entire history of anthropogenic emissions of CFCs, HCFCs, and halons and giving early 20th century levels for CH3CCl3 and CCl4. Significant features of this study are (1) the narrow age spread (spectral width 5 years) of the individual firn air samples, which reveals rapid atmospheric changes, (2) the use of inversion techniques to infer past atmospheric composition with associated uncertainties, and (3) the low analytical detection limit (<0.1 ppt), which, together with the narrow air age spread, detects early background levels and resolves the time that industrial emissions first appeared in the southern hemisphere atmosphere. Integrity of the data is demonstrated by successful intercomparison of data from independent firn sites on Law Dome with common time-series. An upper limit is given for the potential contribution to atmospheric levels of CH3CCl3 from nonindustrial sources. The atmospheric records produced from firn air are compared to calculations based on the history of their global emissions.

Atmospheric inputs of trace metals to the Northeast Atlantic Ocean The importance of southeaste Atmospheric inputs of trace metals to the Northeast Atlantic Ocean The importance of southeaste

Date added: 08/06/2001
Date modified: 07/27/2009
Filesize: 209.3 kB

Spokes et al., 2001 L. Spokes, T. Jickells and K. Jarvis, Atmospheric inputs of trace metals to the northeast Atlantic Ocean: the importance of southeasterly flow, Marine Chemistry 76 (2001), pp. 319–330


Abstract


The study of aerosols and rainwater presented here demonstrates that episodic atmospheric deposition events associated with southeasterly flow are quantitatively significant for large areas of the North Atlantic Ocean. This paper considers aluminium and manganese, with predominantly crustal sources, and lead and zinc, which are mobilised into the atmosphere primarily through anthropogenic activity. High levels of all trace metals are associated with southeasterly flow from Europe as the air passes over heavily populated and industrialised regions before reaching the northeast Atlantic Ocean. Fluxes calculated using the 1% HNO3 acid soluble metal concentration show that, although the climatological norm for this area is westerly flow, short-lived southeasterly transport events dominate the input of trace metals to this ocean region. This material may be toxic to phytoplankton or may be represent a new source of nutrients to the biological community. A significant decrease in atmospheric lead levels in polluted air is seen between June 1996 and May 1997, reflecting the decrease in use of leaded fuels in Europe. Comparing atmospheric flux values to sediment trap metal fluxes shows that the atmosphere represents the dominant source of zinc to the deep ocean, whereas an additional, non-atmospheric, manganese source this required, perhaps from mobilisation of sedimentary material from the continental shelf or long range advection of manganese rich Saharan material.

 

ATMOSPHERIC MEASUREMENTS OF OH, HO2 ATMOSPHERIC MEASUREMENTS OF OH, HO2

Date added: 08/06/2003
Date modified: 07/09/2009
Filesize: 16.18 kB

Bloss, W. J.; Floquet, C.; Gravestock, T. J.; Heard, D. E.; Ingham, T.; Johnson, G. P.; Lee, J. D.,Atmospheric measurements of OH, HO2 and NO by laser-induced fluorescence spectroscopy using a compact all solid-state laser system,EGS - AGU - EUG Joint Assembly, Abstracts from the meeting held in Nice, France, 6 - 11 April 2003, abstract #10521


Abstract


Free-radicals are key intermediates that control the budgets of many trace gases, for example ozone, greenhouse gases and harmful pollutants. Measurement of radicals and comparison with model calculations constitutes an important test of our understanding of the underlying chemistry. There is a greater need for compact and lightweight instruments for the in situ measurement of free-radical species that are suitable for deployment from a number of field-platforms. A new field instrument has been developed that incorporates an all solid-state Nd:YAG pumped titanium sapphire laser that is capable of generating radiation at high pulse-repetition-frequency for the detection of OH, HO_2, NO and IO radicals in the atmosphere by laser induced fluorescence (LIF). The system offers advantages of wide wavelength tunability, compactness, low weight, greater long-term stability (fibre-optic delivery) and short warm-up time. The instrument was successfully deployed during 2002 in the NAMBLEX field campaign at Mace Head with detection limits for OH and HO_2 (measured simultaneously with laser operation at 308 nm) of 3.1 x 10^5 molecule cm-3 (0.012 ppt) and 2.6 x 10^6 molecule cm-3 (0.09 pptv) respectively. Diurnal profiles of OH have been recorded over a period of 5 weeks. NO controls the HO_2/OH ratio and is the critical parameter in the production of tropospheric ozone, yet measurements in the boundary layer are restricted to a single indirect technique based on chemiluminescent analysers. Measurements of NO in the atmosphere have been made by LIF using the new instrument operating at 226 nm, with absolute concentrations in good agreement with simultaneous measurements made using a commercial chemiluminescent analyser. Whilst operating at 445 nm, the instrument has detected the IO radical in the laboratory, with a projected detection limit that is well below previously measured atmospheric concentrations of IO. A second instrument to be deployed on an aircraft platform is currently being developed.

Atmospheric measurements of OH, HO2 and NO by laser-induced fluorescence spectroscopy Atmospheric measurements of OH, HO2 and NO by laser-induced fluorescence spectroscopy

Date added: 08/06/2003
Date modified: 07/27/2009
Filesize: 16.18 kB

Bloss, W. J.; Floquet, C.; Gravestock, T. J.; Heard, D. E.; Ingham, T.; Johnson, G. P.; Lee, J. D.,Atmospheric measurements of OH, HO2 and NO by laser-induced fluorescence spectroscopy using a compact all solid-state laser system,EGS - AGU - EUG Joint Assembly, Abstracts from the meeting held in Nice, France, 6 - 11 April 2003, abstract #10521


Abstract


Free-radicals are key intermediates that control the budgets of many trace gases, for example ozone, greenhouse gases and harmful pollutants. Measurement of radicals and comparison with model calculations constitutes an important test of our understanding of the underlying chemistry. There is a greater need for compact and lightweight instruments for the in situ measurement of free-radical species that are suitable for deployment from a number of field-platforms. A new field instrument has been developed that incorporates an all solid-state Nd:YAG pumped titanium sapphire laser that is capable of generating radiation at high pulse-repetition-frequency for the detection of OH, HO_2, NO and IO radicals in the atmosphere by laser induced fluorescence (LIF). The system offers advantages of wide wavelength tunability, compactness, low weight, greater long-term stability (fibre-optic delivery) and short warm-up time. The instrument was successfully deployed during 2002 in the NAMBLEX field campaign at Mace Head with detection limits for OH and HO_2 (measured simultaneously with laser operation at 308 nm) of 3.1 x 10^5 molecule cm-3 (0.012 ppt) and 2.6 x 10^6 molecule cm-3 (0.09 pptv) respectively. Diurnal profiles of OH have been recorded over a period of 5 weeks. NO controls the HO_2/OH ratio and is the critical parameter in the production of tropospheric ozone, yet measurements in the boundary layer are restricted to a single indirect technique based on chemiluminescent analysers. Measurements of NO in the atmosphere have been made by LIF using the new instrument operating at 226 nm, with absolute concentrations in good agreement with simultaneous measurements made using a commercial chemiluminescent analyser. Whilst operating at 445 nm, the instrument has detected the IO radical in the laboratory, with a projected detection limit that is well below previously measured atmospheric concentrations of IO. A second instrument to be deployed on an aircraft platform is currently being developed.

Atmospheric mercury distribution in Northern Europe and in Atmospheric mercury distribution in Northern Europe and in

Date added: 08/06/2001
Date modified: 07/27/2009
Filesize: 238.69 kB

I. Wangberg, J. Munthe, N. Pirrone, A. Iverfeldt, E. Bahlman, P. Costa, R. Ebinghaus, X. Feng, R. Ferrara, K. Gardfeldt, H. Kock, E. Lanzillotta, Y. Mamane, F. Mas, E. Melamed, Y. Osnat, E. Prestbo, J. Sommar, S. Schmolke, G. Spain, F. Sprovieri, G. Tuncel, Atmospheric mercury distribution in Northern Europe and in the Mediterranean region, Atmospheric EnvironmentVolume 35, Issue 17, , June 2001, Pages 3019-3025.


Abstract


Mercury species in air have been measured at five sites in Northwest Europe and at five coastal sites in the Mediterranean region during measurements at four seasons. Observed concentrations of total gaseous mercury (TGM), total particulate mercury (TPM) and reactive gaseous mercury (RGM) were generally slightly higher in the Mediterranean region than in Northwest Europe. Incoming clean Atlantic air seems to be enriched in TGM in comparison to air in Scandinavia. Trajectory analysis of events where high concentrations of TPM simultaneously were observed at sites in North Europe indicate source areas in Central Europe and provide evidence of transport of mercury on particles on a regional scale.

 

Atmospheric mercury distribution in Northern Europe and in Atmospheric mercury distribution in Northern Europe and in

Date added: 08/06/2001
Date modified: 06/30/2009
Filesize: 238.69 kB

I. Wangberg, J. Munthe, N. Pirrone, A. Iverfeldt, E. Bahlman, P. Costa, R. Ebinghaus, X. Feng, R. Ferrara, K. Gardfeldt, H. Kock, E. Lanzillotta, Y. Mamane, F. Mas, E. Melamed, Y. Osnat, E. Prestbo, J. Sommar, S. Schmolke, G. Spain, F. Sprovieri, G. Tuncel, Atmospheric mercury distribution in Northern Europe and in the Mediterranean region, Atmospheric EnvironmentVolume 35, Issue 17, , June 2001, Pages 3019-3025.


Abstract

 

Mercury species in air have been measured at five sites in Northwest Europe and at five coastal sites in the Mediterranean region during measurements at four seasons. Observed concentrations of total gaseous mercury (TGM), total particulate mercury (TPM) and reactive gaseous mercury (RGM) were generally slightly higher in the Mediterranean region than in Northwest Europe. Incoming clean Atlantic air seems to be enriched in TGM in comparison to air in Scandinavia. Trajectory analysis of events where high concentrations of TPM simultaneously were observed at sites in North Europe indicate source areas in Central Europe and provide evidence of transport of mercury on particles on a regional scale.

 

Atmospheric Methyl Iodide at Cape Grim, Tasmania, from AGAGE Observations Atmospheric Methyl Iodide at Cape Grim, Tasmania, from AGAGE Observations

Date added: 08/05/2003
Date modified: 07/27/2009
Filesize: 264.04 kB

Cohan, D.S., G.A. Sturrock, A.P. Biazar, and P.J. Fraser, Atmospheric methyl iodide at Cape Grim, Tasmania from AGAGE  observations, J. Atmos. Chem., 44, 131-150, 2003.


Abstract


Atmospheric mixing ratios of methyl iodide (CH3I) and other methyl halides have been measured at Cape Grim, Tasmania (41°S, 145°E), since early 1998 as part of the Advanced Global Atmospheric Gases Experiment (AGAGE). This paper analyses about 1700 ambient air CH3I measurements from the 14-month period (March 1998–April 1999). Mixing ratios peaked during the summer, despite faster photolytic loss, suggesting local oceanic emissions were about 2.2–3.6 times stronger in summer than in winter. Back trajectories show that CH3I levels are strongly dependent on air mass origin, with highest mixing ratios in air from the Tasman Sea/Bass Strait region and lowest levels in air originating from the Southern Ocean at higher latitudes. CH3I mixing ratios were not well correlated with other methyl halides in unpolluted marine air. The large variations with season and air mass origin suggest that high frequency, continuous data from key locations will make a significant contribution to the understanding of sources and sinks of this important short-lived atmospheric species.

Atmospheric modeling of high- and low-frequency methane observations Importance of interannuall Atmospheric modeling of high- and low-frequency methane observations Importance of interannuall

Date added: 08/06/2005
Date modified: 07/27/2009
Filesize: 1.92 MB

Chen, Y.-H., and R. G. Prinn (2005), Atmospheric modeling of high- and low-frequency methane observations: Importance of interannually varying transport, J. Geophys. Res., 110, D10303, doi:10.1029/2004JD005542.


Abstract


We compare modeled and observed atmospheric methane (CH4) between 1996 and 2001, focusing on the role of interannually varying (IAV) transport. The comparison uses observations taken at 13 high-frequency (∼hourly) in situ and 6 low-frequency (∼weekly) flask measurement sites. To simulate atmospheric methane, we use the global 3-D chemical transport model (MATCH) driven by NCEP reanalyzed winds at T62 resolution (∼1.8° × 1.8°). For the simulation, both methane surface emissions and atmospheric sink (OH destruction) are prescribed as annually repeating fields; thus, atmospheric transport is the only IAV component in the simulation. MATCH generally reproduces the amplitude and phase of the observed methane seasonal cycles. At the high-frequency sites, the model also captures much of the observed CH4 variability due to transient synoptic events, which are sometimes related to global transport events. For example, the North Atlantic Oscillation (NAO) and El Niño are shown to influence year-to-year methane observations at Mace Head (Ireland) and Cape Matatula (Samoa), respectively. Simulations of individual flask measurements are generally more difficult to interpret at certain sites, partially due to observational undersampling in areas of high methane variability. A model-observational comparison of methane monthly means at seven coincident in situ and flask locations shows a better comparison at the in situ sites. Additional simulations conducted at coarser MATCH resolution (T42, ∼2.8° × 2.8°) showed differences from the T62 simulation at sites near strong emissions. This study highlights the importance of using consistent observed meteorology to simulate atmospheric methane, especially when comparing to high-frequency observations.

 

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.

Atmospheric Particles from organic Vapours Atmospheric Particles from organic Vapours

Date added: 08/06/2002
Date modified: 06/30/2009
Filesize: 99.71 kB

O'Dowd, Colin D.; Aalto, Pasi; Hmeri, Kaarle; Kulmala, Markku; Hoffmann, Thorsten, Aerosol formation: Atmospheric particles from organic vapours, Nature, Volume 416, Issue 6880, pp. 497-498 (2002)


Abstract

 

Aerosol particles produced over forested areas may affect climate by acting as nuclei for cloud condensation, but their composition (and hence the chemical species that drive their production) remains an open question. Here we show, to our knowledge for the first time, that these newly formed particles (3-5 nm in diameter) are composed primarily of organic species, such as cis-pinonic acid and pinic acid, produced by oxidation of terpenes in organic vapours released from the canopy.

Atmospheric Sulphur Levels in Western Ireland Atmospheric Sulphur Levels in Western Ireland

Date added: 08/07/1969
Date modified: 07/27/2009
Filesize: 2.97 MB
O'Connor. TC., Atmospheric Sulphur Levels In Western Ireland, Sulphur in Agriculture, AN Foras Taluntais, Dublin, 1969

Abstract

 

Sulphur compounds can exist in the atmosphere in the solid, liquid or gaseous form, depending on their origin and subsequent history. They have deleterious effect on the health of humans, plants and animals and by their corrosive action on buildings and other materials. They have also been studied for their beneficial effects, for example, the nutrition of plants and other natural processes in soils and weathering. They can also be involved in processes of cloud formation and the geochemistry around the world. Although there have been many studies or atmospheric sulphur levels in polluted areas there is little data available on the natural background concentrations of sulphur dioxide in unpolluted areas in temperate latitudes.

This paper is concerned with some aspects of the atmospheric portion of the natural cycle of sulphur. it describes some investigations into the concentrations of sulphur dioxide at a variety of sites. in Galway city, Sine references to recent paper on specific aspects of the sulpur cycle are also given.

Attenuated total reflectance measurements of the complex refractive index of kaolinite powder at CO2 laser wavelengths Attenuated total reflectance measurements of the complex refractive index of kaolinite powder at CO2 laser wavelengths

Date added: 07/31/1985
Date modified: 06/30/2009
Filesize: 1.63 MB

Pinnick, R.G., Jennings, S.G., Boice, D.C., and Cruncleton, J.P. (1985). - Attenuated total reflectance measurement of the complex refractive index of kaolinite powder at CO2 laser wavelengths. Appl. Opt., 24, 3274 - 3285.


Abstract

 

Attenuated total reflectance measurements of the complex refractive index of kaolinite powder-air mixtures are made for nine CO2 laser wavelengths. The Maxwell-Garnett effective medium theory and generalizations of it that account for either the shape distribution of kaolinite grains in the medium (in which the grains are approximated by a shape distribution of small arbitrarily oriented ellipsoids) or the size distribution of grains (in which finite grain sizes are accounted for by considering, in addition to the electric dipole interaction, magnetic dipole and electric quadrupole interactions) are used to deduce from these measurements the complex refractive index of kaolinite. Most success is achieved with a generalization which assumes a shape distribution of small ellipsoidal grains but which neglects all but electric dipole interactions. In spectral regions where kaolinite displays very strong absorption (in the 9.6-10-,um spectral region) all effective medium theory solutions for kaolinite refractive index either are plagued with ill-conditioning or are nonphysical. It appears that the attenuated total reflectance method, at least as we have applied it here to loosely packed powders comprised of nonspherical grains, is not suitable for measurement of powders in spectral regions of strong absorption.

Attenuated total Reflectance Measurements of the complex refractive index of polystyrene latex at CO2 laser wavelengths Attenuated total Reflectance Measurements of the complex refractive index of polystyrene latex at CO2 laser wavelengths

Date added: 07/31/1981
Date modified: 06/30/2009
Filesize: 1.62 MB
Jennings, S.G. (1981)- Attenuated total Reflectance Measurements of the complex refractive index of polystyrene latex at CO2 laser wavelengths. J. Opt. Soc. Amer., 71, 923-927.
Abstract

 

Attenuated total reflectance (ATR) measurements of the complex refractive index m of 5, 10,15, 20, and 30% water suspensions of polystyrene latex are presented for CO2 laser wavelengths (measurements for the 30% suspension are for X =10.591 ,um only). The use of the Maxwell Garnet mixture rule for the real index and the imaginary index (at X = 9.305 ,um) and an extrapolation scheme for the remaining values of imaginary index yield the values m =
1.709 - 0.07i (X = 9.305 ,tm); m = 1.887 - 0.06i (X = 9.504 Arm); m = 1.705 - 0.04i (X = 9.694 ,um); m = 1.764 - 0.045i (X = 10.591 ,um). ATR measurements of the complex index of water and water-ammonium sulfate solutions are in reasonably good agreement with those previously published.

Averaging periods for indoor-outdoor ratios of pollution in naturally ventilated non-domestic buildings near a busy road Averaging periods for indoor-outdoor ratios of pollution in naturally ventilated non-domestic buildings near a busy road

Date added: 08/01/2003
Date modified: 06/30/2009
Filesize: 387.68 kB

Ni Riain, C, Mark, D., Davies, M., Harrison, R.M. and Byrne, M.A. Averaging periods for indoor-outdoor ratios of pollution in naturally ventilated non-domestic buildings near a busy road. Atmos Env, Vl 37, pp 4121-4132 , 2003.


Abstract

 

Continuous measurements of carbon monoxide (CO) and particulate matter (PM10, PM2.5 and PM1) were made inside and outside two naturally ventilated (NV) and two mechanically assisted (MV) spaces overlooking the same six-lane highway in Central London. The indoor/outdoor (I/O) ratio was calculated for each site for the whole monitoring period in the usual way, and then cumulatively at each hourly time-step from the start of monitoring up to the whole period in order to track the evolution of the I/O ratio with length of monitoring or averaging period. Hourly data were also sorted by wind speed and direction and I/O ratios calculated for each direction/speed set from ensemble means. I/O ratios for the whole period were generally lower in the NV spaces than the MV, however, the indoor-outdoor relationship in the NV spaces was found to vary substantially with wind direction. For a constant above-roof wind speed, I/O ratios of CO varied by 50-60% about the mean value with direction, and by 20-30% for particulate matter. Consequently, I/O ratios for NV spaces depended on the distribution of wind direction within the calculation period and, hence, on the length of monitoring period. The I/O ratio in one NV space changed by a factor of three between the early stages and final stages of monitoring, with a stable final value (±5%) achieved after 900 h of monitoring. By contrast, in the MV spaces under constant fan speed, constant values for the I/O ratio were achieved for CO within 4 h of the start of monitoring. It is argued here that field assessments of the filtration performance of naturally ventilated spaces need to consider exposure to and distribution of natural ventilation drivers within the monitoring period in order to draw meaningful comparisons for design and exposure assessment purposes.

Backround Bioaerosol Measurements at Mace Head Backround Bioaerosol Measurements at Mace Head

Date added: 08/26/1998
Date modified: 07/27/2009
Filesize: 113.15 kB

Kenny, C.M., and Jennings, S.G. (1998). Background bioaerosol measurements at Mace Head. J. Aerosol Sci., 29, S779-S780.


Abstract


Primary biological aerosol particles consist of airborne viable or non-viable material which are an ubiquitous component of the atmospheric aerosol. The types of particles considered as bioaerosols cover a very large size range, smallest in size are viruses (- 0.005 pm < radius< - 0.25 pm); larger particles include bacteria (r > - 0.2 pm), algae spores and fungi (r > - 0.5 pm) and pollen grains (r > - 5 pm), (Macher, 1993). Plant debris like leaf litter, parts of insects and human and animal epithhelial cells have a supposed r > - 1 pm. Assessment of bioaerosols is generally more complicated than that of non-bioaerosols - for example bioaerosol viability may be affected by a variety of stresses (desiccation, radiation, oxygen toxicity, chemical pollutants etc.) in the environment. A background bioaerosol measurement programme is currently taking place at the Mace Head Atmospheric Field Research Station, Carna, Co. Galway. Effective biological analysis of airborne particles requires samplers operating at a high flow rate and with the capability of concentrating the air particles into a fairly small liquid volume. Use has been made of a glass Aerojet cyclone high volume sampler which has been proven to be successful for the collection of bioaerosol material. Cyclones with spray wetters have been found to be gentle with airborne microorganisms and help to maintain cell viability levels. Utilising a blue protein dye,  uantitative determination of the percentage biological and non-biological species present in the aerosol has been made. The  staining solution reacts with the carboxyl group of a protein and therefore stains the protein-containing or biological particles blue. Non-biologicals are not changed by the stain. Under the light microscope the effects of the protein dye on different particle types can be seen and biological particles can be classified by their characteristic morphology and size. Filters have been examined using a Leitz microscope (Laborlux S), equipped with a 10x ocular lens and an objective lens, Plan 40, and size distribution spectra of the bioaerosol species have been measured. The samples were evaluated into size classes (3.5 urn < diameter < 40 urn) and size distributions of the total aerosol were obtained. The percentages of biological particles in the corresponding size classes are shown in Figure 1. The highest percentage of total biological particles < 10 urn occurs during the modified marine periods 07/25/97 and 07/l l/97 which reflects the passage of the air mass over land. The marine sample 07/15/97 shows a consistently high percentage of biological particles over the larger size ranges. The two predominant peaks occuring during the marine period 07/04/97 are caused by spores. Coupling size distribution spectra with corrected fluorescence spectra of the same air sample yield quantitative effective fluorescence cross-section per unit volume of background air. Analysis of size distribution spectra of the total aerosol, will be presented for both maritime and polluted air.

Backscatter and Extinction in Water Clouds Backscatter and Extinction in Water Clouds

Date added: 07/31/1983
Date modified: 06/30/2009
Filesize: 2.64 MB

Pinnick, R.G., Jennings, S.G., Chylek, P., Ham, C., and Grandy, W.T. Jr. (1983)- Backscatter and extinction in water clouds. J. Geophys. Res., 88, 6787-6796.


Abstract


An approximate relation between the volume extinction coefficient σe and backscatter coefficient σb of atmospheric cloud at visible and near-infrared wavelengths is derived. The relation is only weakly dependent on the size distribution of droplets and has the form σe/σb=(8π/g){1+k-2/3(<r 4/3>/<r2>) -δ[k2(<r4>/<r2>)+k4/3(< r4/2><r4>/<r2><r2>)]} where the extinction efficiency is approximated by a complex-angular-momentum-theory result and the parameters g and δ are determined by approximating a running mean of the backscatter gain by G(x)=g(1+δx2) (x is droplet size parameter and δ<<1), k is the wave number, and <rn> is the nth moment of the droplet size distribution. To zero order the relation is linear and independent of the droplet size distribution σe=[8π/g(λ)]σb where g(λ) is a slowly varying function of wavelength. At a wavelength λ=1.06 μm the relation is σe (km-1)=18.2 σb (km-1sr-1). Predictions made with this simple zero-order approximation are in good agreement (within 50%) with Mie calculations of extinction and backscatter coefficients based on 156 measurements of cloud droplet spectra in cumulus and stratus type clouds. The linear σe-σb relation is also in agreeement with extinction and backscatter measurements made on laboratory-generated fog droplet distributions. The relation suggests that visible or near-infrared extinction coefficients in cloud of unknown type could be inferred from lidar backscatter measurements alone, without knowledge of the cloud droplet size spectra, barring complications arising from multiple scattering contributions to the lidar return.

Backscatter and extinction measurements in cloud and drizzle at CO2 laser wavelengths Backscatter and extinction measurements in cloud and drizzle at CO2 laser wavelengths

Date added: 07/31/1986
Date modified: 06/30/2009
Filesize: 1.09 MB

Jennings, S.G. (1986). - Backscatter and extinction measurements in cloud and drizzle at CO2 laser wavelengths. Appl. Opt., 25, 2499 - 2505.


Abstract


The backscatter and extinction of laboratory generated cloud and drizzle sized drops have been measured at CO2 laser wavelengths (predominately at λ = 10.591 µm). Measurements of volume backscatter coefficient σb and volume extinction coefficient σe for laboratory cloud of predominantly <20-µm radius droplets are dependent on the form of the size distribution in agreement with numerical prediction. For drops of >˜20 µm at λ = 10.591 µm the relation between σe and σb has the appealingly simple size distribution independent form of σeb =8π/G,[equation] is the asymptotic value of the backscatter gain, where n and k are the real and imaginary indices of refraction. The linear relation is in good agreement with extinction and backscatter measurements made on laboratory generated drizzle sized drops (r > 20 µm). This suggests that the extinction coefficient at CO2 laser wavelengths could be inferred from lidar backscatter return signals without requiring knowledge of the size distribution for drizzle and spherical precipitation sized water drops.

Behavior of ultrafine particles in continental and marine air masses at a rural site in the Uni Behavior of ultrafine particles in continental and marine air masses at a rural site in the Uni

Date added: 08/06/2000
Date modified: 07/09/2009
Filesize: 1.44 MB

Coe H., P. I. Williams, G. McFiggans, M. W. Gallagher, K. M. Beswick, K. N. Bower and T. W. Choularton Behavior of ultrafine particles in continental and marine air masses at a rural site in the United Kingdom. J. Geophys. Res., 105, 26891-26905, 2000


Abstract


Particle size distribution measurements were made at a coastal site in the United Kingdom. These are presented, and the behavior of recently formed ultrafine particles is discussed. No ultrafine particles were observed in maritime air masses; however, 3 to 7 nm particles were frequently observed at enhanced concentrations when the wind direction was from the land. Their formation was favored at lower temperatures, when 1 ppbv or more of SO2 was present and in air masses that had not been aged extensively. On days when enhanced ultrafine particle concentrations were observed, 3 nm particles increased sharply in the morning, approximately 30 to 90 min after the UV solar flux first increased. By early afternoon the ultrafine particle concentration had returned to background levels. Rapid measurements of 5 nm particles showed no correlation with turbulence parameters, although the boundary layer mixing scales were similar to growth times of freshly nucleated particles to 5 nm diameter. However, ultrafine particle concentrations do correlate with the availability of sulphuric acid vapor. A delay of approximately an hour between the increase of H2SO4 in the morning and a large increase in ultrafine particle concentrations is due to the growth of particles to observable sizes, not the nucleation process itself. An analysis of the timescales for growth showed that coagulation may be important immediately after the particles have nucleated but its effectiveness reduces as number concentration falls. Conversely, growth by condensation is initially slow due to the Kelvin effect but increases in importance as the particles reach observable sizes.

 

Biogenic aerosol formation in the boreal forest Biogenic aerosol formation in the boreal forest

Date added: 07/31/2000
Date modified: 07/01/2009
Filesize: 469.52 kB

Kulmala, M. K. Hämeri, J.M. Mäkelä, P. P. Aalto, L. Pirjola, M. Väkevä, E. D. Nilsson, I.K.Koponen, G. Buzorius, P. Keronen, g. Rannik, L. Laakso, T. Vesala, K. Bigg, W. Seidl, R. Forkel, T. Hoffmann, J. Spanke, R. Jansson, M. Shimmo, H-C. Hansson, C.D. O'Dowd, E. Becker, J. Paatero, K. Teinilä, R. Hillamo, amd Y. Viisanen, Biogenic aerosol formation in the boreal forest, Boreal Environment Research, 4, 279-280, 2000


Abstract


Aerosol formation and subsequent particle growth in the ambient air have been frequently observed at the boreal forest site (SMEAR II station), southern Finland. The EU funded project BIOFOR (Biogenic aerosol formation in the boreal forest) has focused on a) the determination of formation mechanisms of aerosol particles in the boreal forest site, and b) the verification of emissions of secondary organic aerosols from the boreal forest site, including the quantification of the amount of condensable vapours produced in photochemical reactions of biogenic volatile organic compounds (BVOC) leading to aerosol formation. Although the exact formation route for 3 nm particles is still unclear, the project results can be summarised as follows: (i) The most probable formation mechanism is ternary nucleation (water-sulphuric acid-ammonia) and the growth to observable sizes is mainly due to condensation of organic vapours. However, we do not have a direct proof of these phenomena, since it is impossible to determine the composition of 1 to 5-nm-size particles using the present state-of-art instrumentation; (ii) If nucleation takes place, it always occurs in cold-air advection in polar and Arctic air masses at low cloudiness, and the nucleation is closely connected to the onset of strong turbulence, convection, and entrainment in the morning-noon transition from a stable to an unstable stratified boundary layer; (iii) The emissions rates for several gaseous compounds have been verified. The model calculations showed that the amount of the condensable vapour needed for observed growth of aerosol particles is in the range 1–5 x 107 cm–3. The estimations for the vapour source rate are in the range 3–8 x 104 cm–3s–1.

Biogenic coastal aerosol production and its influence on aerosol radiative properties Biogenic coastal aerosol production and its influence on aerosol radiative properties

Date added: 07/31/2001
Date modified: 07/27/2009
Filesize: 562.71 kB
O'Dowd, C.D., Biogenic coastal aerosol production and its influence on aerosol radiative properties, J. Geophys. Res., 106, 1545-1550, 2001

Abstract


Coastal zones have been shown to provide a massive source of new, tidal-related, aerosol particles in the atmospheric boundary layer with concentrations exceeding 1,000,000 cm−3 during nucleation bursts sustained over many hours [O Dowd, 200O]. While coastal regions are very strong sources of natural aerosol particles, hithertofore, it has not been demonstrated that these particles contribute to aerosol-related radiative flux. In this brief report, evidence is presented for growth of these new particles, following tidal-related particle formation, into radiatively active particle sizes (i.e. radius>50 nm) where an increase in concentration of more than 300% can be seen. This increase of radiatively active particles concomitantly results in more than a threefold enhancement in both aerosol scattering ability (thereby influencing direct radiative flux) and cloud condensation nuclei (CCN) availability (thereby influencing indirect radiative flux). These results provide direct evidence for coastal biogenic emissions significantly enhancing the radiative flux potential of atmospheric aerosols.

Biogenic fluxes of halomethanes from Irish peatland ecosystems Biogenic fluxes of halomethanes from Irish peatland ecosystems

Date added: 08/06/2001
Date modified: 07/01/2009
Filesize: 278.07 kB

Dimmer, C.H., P.G. Simmonds, G.N. Nickless, and M.R. Bassford, Biogenic fluxes of halomethanes from Irish Peatland Ecosystems, Atmos. Environ., 35(2), 321-330, 2001, (Ser. No. ACP108)


Abstract


Irish peatland ecosystems have been shown to be important sources of low molecular weight halocarbons. Emission of CH3Br, CH3Cl, CH3I and CHCl3 was recorded from all peatland sites monitored, with minor flux of other halocarbons at certain sites. Fluxes were found to be highly linked to incident light, with strong diurnal cycles recorded at all open peatland sites. Estimates of halomethane emissions, particularly from coastal peatland and conifer plantation forest floor sites, suggests that these ecosystems may make a significant contribution to the global budgets of several important halocarbons. Global annual fluxes of 4.7 (0.1-151.9), 0.9 (0.1-3.3), 5.5 (0.9-43.4), and 1.4 (0.1-12.8) Ggyr-1 for CHCl3, CH3Br, CH3Cl, and CH3I, respectively, were determined for peatland ecosystems.

 

Biogenic iodine emissions and identification of end products in coastal ultrafine particles during nucleation bursts Biogenic iodine emissions and identification of end products in coastal ultrafine particles during nucleation bursts

Date added: 07/31/2002
Date modified: 07/27/2009
Filesize: 703.95 kB
J.M. Mäkelä, T. Hoffmann, C. Holzke, M. Väkevä, T. Suni, T. Mattila, P.P. Aalto, U. Tapper, E.I. Kauppinen and C.D. O'Dowd, Biogenic iodine emissions and identification of end products in coastal ultrafine particles during nucleation bursts. J. Geophys. Res. 107, 10.1029/2001JD000580,

Abstract


Ultrafine particles sampled during new particle formation bursts observed in the coastal zone were studied with transmission electron microscopy (TEM) and elemental analysis using energy-dispersive X ray (EDX). It was observed that both iodine and sulphur were present in the new particles with diameter below 10 mn. Gaseous emissions of halogen compounds from seaweeds were also measured at the same location during low-tide particle nucleation episodes. Based on the presence of iodine in the particle phase during low-tide nucleation bursts, and the significant emission of iodine compounds from the seaweeds during these periods, it is apparent that part of the biogenic iodine species emitted from the seaweeds end up in the ultrafine particulate phase. It was not possible to quantitatively determine the iodine content in the particles; however, in most cases the relative contribution from iodine and sulphate was similar, while some cases indicated no sulphate. On larger sized particles the contribution of sulphate was significantly higher than iodine. It appears that the condensable species leading to the appearance of new particles in the coastal atmosphere is an iodine species. Whether or not this iodine species also participates in the nucleation of new stable clusters could not be completely verified.

Biogenic sulphur emissions and inferred non-sea-salt-sulphate CCN around Antarctica Biogenic sulphur emissions and inferred non-sea-salt-sulphate CCN around Antarctica

Date added: 08/06/1997
Date modified: 07/01/2009
Filesize: 1.53 MB

O'Dowd, C. D., J. A. Lowe, M. H. Smith, B. Davison, C. N. Hewitt, and R. M. Harrison (1997), Biogenic sulphur emissions and inferred non-sea-salt-sulphate cloud condensation nuclei in and around Antarctica, J. Geophys. Res., 102(D11), 12,839–12,854.


Abstract


Accumulation mode aerosol properties and biogenic sulphur emissions over the South Atlantic and Antarctic Oceans are examined. Two contrasting air masses, polar and maritime, each possessing distinct aerosol properties, were encountered during the summer months. By examining aerosol volatile properties, polar air masses arriving from the Antarctic continent were shown to consist primarily Of H2SO4 in the accumulation mode size range, with inferred NH+ 4 to SO= 4 molar ratios close to zero. By comparison, air masses of temperate maritime origin were significantly neutralized with molar ratios of ≈1. These results suggest a deficit of ammonia in polar air masses compared with that in maritime air masses. Dimethyl sulphide (DMS) exhibited no correlation with its putative aerosol oxidation products, although spatial coherence in atmospheric concentrations of DMS, methane sulphonic acid (MSA), and non-sea-salt (nss)-sulphate mass was observed. Volatility analysis, used to infer nss-sulphate cloud condensation nuclei (nss-sCCN) active at a supersaturation of ≈0.2%, indicates that nss-sCCN mass and number concentration were best correlated with MSA mass (r≈0.63). Aerosol volatility identified the presence of MSA in submicron non-sea-salt aerosol; however, its contribution to the aerosol mass was small relative to the contribution of sulphuric acid and ammonium bisulphate/sulphate aerosol. The marine sulphur cycle appears strongly coupled to the sea-salt cycle with, typically, 80–90% of nss-sulphate thought to be internally mixed with sea-salt aerosol. During the austral Summer of 1992/1993, a period of strong biological productivity in the Weddell Sea and sub-Antarctic Ocean, particularly during ice-melt, the cruise-average DMS flux of 61 μg m−2 d−1 corresponded to a very modest average nss-sCCN concentration of 21 cm−3. Observed peak values of DMS flux and inferred nss-CCN concentrations during the cruise were 477 μg m−2 d−1 and 64 cm−3, respectively. Events of new particle formation were identified in the Weddell Sea and occurred under conditions of high DMS flux and low aerosol surface area.

 

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