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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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Interannual variability over the eastern North Atlantic Ocean Chemical and meteorological evide Interannual variability over the eastern North Atlantic Ocean Chemical and meteorological evide

Date added: 08/06/1994
Date modified: 07/24/2009
Filesize: 1.53 MB

Doddridge, B. G., P. A. Dirmeyer, J. T. Merrill, S. J. Oltmans, and R. R. Dickerson (1994), Interannual variability over the eastern North Atlantic Ocean: Chemical and meteorological evidence for tropical influence on regional-scale transport in the extratropics, J. Geophys. Res., 99(D11), 22,923–22,935.


Abstract


Observed boreal fall season (September–November) 1991 surface CO data from Mace Head, Ireland, are characterized by particularly high mixing ratios, as evidenced by high means, medians, and maxima for those months, relative to the same dato for boreal fall 1992. Air parcels characterized by elevated CO during fall 1991 are attributed to European sources on the basis of isentropic back trajectory analysis. A histogram of the 1991 data shows a bimodal distribution representing two discrete source regions, North Atlantic and European, while the 1992 data show only one mode, representing primarily zonal westerly flow over the North Atlantic Ocean. A similar distinction exists in O3 data between the two years. Considerable interannual variability has important implications for observationalists and modelers alike; an inherent uncertainty is introduced by basing any determination of trend from only a few years of data. An isentropic flow climatology for Mace Head illustrates significant differences in the regional-scale flow patterns to Mace Head between the 1991 and the 1992 fall seasons. These differences have been examined in terms of general dynamical principles and tropical/extratropical coupling. There is evidence of the existence of Rossby wave links with the tropical upper troposphere over South America and the central Pacific Ocean which are responsible for the climatic forcing giving rise to the observed interannual variation in large-scale flow patterns and influencing the chemical character of air parcels reaching Mace Head. Using CO as a tracer for short-lived continental anthropogenic O3 precursors and calculating ΔO3/ΔCO for air parcel trajectories following anticyclonic paths over western Europe during the late summer and fall season of 1991, we estimate O3 production over western Europe at about 66 (40–96) billion moles of O3 per summer (∼3 Tg O3 per summer), based on 1985 CO emission inventory dam (37 Tg CO yr−1 for western Europe).

 

Particle counting and numerical models: Effect of instrumental size resolution and particle shapes o Particle counting and numerical models: Effect of instrumental size resolution and particle shapes o

Date added: 08/05/2006
Date modified: 08/05/2009
Filesize: 245.54 kB

Karine Chamaillard, S.G. Jennings, Particle counting and numerical models: Effect of instrumental size resolution and particle shapes on optical cross-sections, Journal of Quantitative Spectroscopy and Radiative Transfer, Volume 100, Issues 1-3, VIII Conference on Electromagnetic and Light Scattering by Nonspherical Particles, July-August 2006, Pages 64-76, ISSN 0022-4073, DOI: 10.1016/j.jqsrt.2005.11.064.

 


Abstract


The effect of instrumental size resolution measurements on numerical calculations of optical cross-sections is investigated. The particle counting instruments considered are a FSSP-300, a large scattering angle probe instrument similar to a ASASP-X, and, an aerodynamical system ELPI instrument. The scattering and hemispheric backscattering cross-sections, Csca and Cbk, are calculated on the basis that the full width of the instrumental size bin should be considered in modeling. An average process is applied on these quantities over the full size bin of the instrument; they are then compared to their usual estimation on the single mean diameter Dp per channel. The effect of particle shape is investigated with ellipsoids and spheres. Results show sensitivity of the optical cross-sections to the shape of the particles as well as position of the mean geometrical diameter Dp of the channels within the interferences modes of the scattering efficiencies. The value of the width of the size bins, d log D, of each channel is crucial in the results. This comparison gives a useful estimation of error important in optical particle counting instruments based on inversion process of optical quantities. In addition, accuracy of size distribution measurements is found not to be representative of accuracy in the calculations of optical cross-sections.

External influences on Europe's air quality Baseline methane, carbon monoxide and ozone from 19 External influences on Europe's air quality Baseline methane, carbon monoxide and ozone from 19

Date added: 08/07/2006
Date modified: 07/24/2009
Filesize: 645.4 kB

Derwent, RG, Simmonds, PG, O'Doherty, S, et al , External influences on Europe''s air quality: Baseline methane, carbon monoxide and ozone from 1990 to 2030 at Mace Head, Ireland, ATMOS ENVIRON, 2006, Vol: 40, Pages: 844 - 855, ISSN: 1352-2310


Abstract


A global 3-D chemistry-transport model STOCHEM has been employed to study trends in the mole fractions of methane, carbon monoxide and ozone in baseline air masses entering Europe from the Atlantic Ocean over the period from 1990 to 2030. With a range of emission scenarios for man-made ozone precursor emission sources available, a wide range of model trends were predicted for the period up to 2030. In the scenario based on current planned air pollution controls, IIASA CLE, methane shows a strong upward trend, ozone shows a weaker upward trend, and carbon monoxide is approximately flat in baseline air masses. In one of the more pessimistic IPCC SRES scenarios, A2, all three gases show future increases. However, in the scenario based on maximum feasible emission reductions, IIASA MFR all three trace gases decline. By 2030, projected climate change reduces the growth in CH4, but has insignificant effects on baseline CO and O3 in these simulations. Global or hemispheric ozone precursor emissions and their controls exert a potentially large external influence on Europe’s air quality. This influence is currently not taken into account in future European air quality policy formulation.
r 2005 Elsevier Ltd. All rights reserved.

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.

 

Air Pollution Measurements at Macehead Air Pollution Measurements at Macehead

Date added: 08/07/1988
Date modified: 09/11/2009
Filesize: 2.14 MB

Long-term measurements of atmospheric mercury at Mace Head, Irish west coast, between 1995 and Long-term measurements of atmospheric mercury at Mace Head, Irish west coast, between 1995 and

Date added: 08/07/2002
Date modified: 07/24/2009
Filesize: 236.55 kB

Long-term measurements of atmospheric mercury at Mace Head, Irish west coast, between 1995 and 2001 R. Ebinghaus, H.H. Kock, A.M. Coggins, T.G. Spain, S.G. Jennings, C. Temme Atmos. Environ., 36, 5267-5276, 2002


Abstract


Monitoring of atmospheric mercury concentrations has been carried out at the Mace Head atmospheric research station on the west coast of Ireland between September 1995 and December 2001. Measurements were carried out with a time resolution of 15 min. No trend in the concentration levels has been detected during the measurement period, with the annual average concentrations remaining constant at 1.75 ng m−3. A slight increase in the concentration levels is derived, if only clean sector filtered air masses clearly of marine origin are used.

The Mace Head data set shows a seasonal pattern with higher monthly mean concentrations in the winter months. Comparison with two continental sites in Sweden shows, that atmospheric mercury concentrations at the western inflow boundary are on an average higher than those at the two continental sites, expressing a west to east decreasing concentration gradient.

At Mace Head, no indications for so-called Mercury Depletion Events (MDEs), recently reported for a number of sites in the Arctic and in the Antarctic, have been found between 1995 and 2001.

 

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.

Potential for photochemical ozone formation in the troposphere over the North Atlantic as deriv Potential for photochemical ozone formation in the troposphere over the North Atlantic as deriv

Date added: 08/06/2002
Date modified: 07/23/2009
Filesize: 1.34 MB

Reeves, C. E., et al. (2002), Potential for photochemical ozone formation in the troposphere over the North Atlantic as derived from aircraft observations during ACSOE, J. Geophys. Res., 107(D23), 4707, doi:10.1029/2002JD002415.


Abstract


In this paper, ozone (O3), water vapor (H2O), carbon monoxide (CO), and peroxide concentrations and photolysis rates measured in the troposphere over the North Atlantic during two Atmospheric Chemistry Studies in the Oceanic Environment (ACSOE) aircraft field campaigns are used to calculate the concentration of nitric oxide (NO) required for net photochemical O3 production (nPO3) to be positive (NOcomp). NOcomp tended to show a decrease with altitude, although it was sometimes found to be low in the marine boundary layer (MBL) where H2O concentrations were high and O3 concentrations were low. nPO3 was calculated for the spring when NO data were available and was found to be mostly negative and generally increased from about −0.5 to −0.2 ppbv hr−1 in the MBL to +0.04 ppbv hr−1 at about 7–8 km altitude. The results suggest that much of the lower and middle troposphere over the eastern North Atlantic during spring is in a state of slow net photochemical O3 destruction. However, in the upper troposphere, the system changes to one of net photochemical production, which results from the drier environment and higher NO concentrations. Furthermore, examples of net O3 production were also observed in the lower and middle troposphere associated with either in situ sources of NO or long-range transport of pollution. The paper also illustrates the sensitivity of this O3 production/loss state to H2O and NO concentrations, photolysis rates, and temperatures.

 

Comparison of calculated and measured peroxide data collected in marine air to investigate prom Comparison of calculated and measured peroxide data collected in marine air to investigate prom

Date added: 08/06/1998
Date modified: 07/27/2009
Filesize: 1007.98 kB

Penkett, S.A., Reeves, C.E., Bandy, B.J., Kent, J.M., and Richer, H.R., Comparison of calculated and measured peroxide data collected in marine air to investigate prominent features of the annual cycle of ozone in the troposphere, J. Geophys. Res., 103 (D11): 13377-13388, 1998.


Abstract


Large amounts of data on the concentration of peroxides have been collected in vertical profiles over the North Atlantic Ocean by a Hercules aircraft. The measured peroxide concentrations have been compared with concentrations calculated by a simple algorithm derived assuming that the standing peroxide concentration is in equilibrium with its production and loss processes. In clean air where the peroxide and ozone concentrations are anticorrelated throughout the profile measured and calculated peroxide concentrations coincide, whereas in layers of polluted air within the profile, as determined from positive ozone peroxide correlations, calculated peroxide concentrations are greatly in excess of measured values. Using the degree of correlation between measured and calculated peroxide concentrations as a diagnostic, it is possible to show that many aspects of the seasonal cycle of ozone are caused by in situ tropospheric chemistry. Thus the summer minimum in the seasonal cycle of ozone, observed at clean marine ground-based sites such as Mace Head, is due to photochemical destruction, and elevated levels of ozone are associated with the transport of polluted air, on occasion over thousands of kilometers. Of particular interest if our analysis is correct, the broad maximum of ozone occurring between March and May at ground-based sites has a large contribution from ozone formed by tropospheric as well as stratospheric chemistry.

 

Minimizing light absorption measurement artifacts of the Minimizing light absorption measurement artifacts of the

Date added: 02/15/2011
Date modified: 02/15/2011
Filesize: 2.71 MB

Collaud Coen, M., E. Weingartner, A. Apituley, D. Ceburnis, R. Fierz-Schmidhauser, H, Flentje, J.S. Henzing,  S.G. Jennings, M. Moerman, A. Petzold, O. Schmid, and U. Baltensperger. Minimizing light absorption measurement artifacts of the Aethalometer: evaluation of five correction algorithms: the EUSAAR protocol. Atmos. Meas.Technol., 3, 457-474, 2010.


The aerosol light absorption coefficient is an essential parameter involved in atmospheric radiation budget

calculations. The Aethalometer (AE) has the great advantage of measuring the aerosol light absorption coefficient at several wavelengths, but the derived absorption coefficients are systematically too high when compared to reference methods. Up to now, four different correction algorithms of the AE absorption coefficients have been proposed by several authors. A new correction scheme based on these previously published methods has been developed, which accounts for the optical properties of the aerosol particles embedded in the filter. All the corrections have been tested on six datasets representing different aerosol types and loadings and include multi-wavelength AE and white-light AE. All the corrections have also been evaluated through comparison with a Multi-Angle Absorption Photometer (MAAP) for four datasets lasting between 6 months and five years. The modification of the wavelength dependence by the different corrections is analyzed in detail. The performances and the limits of all AE corrections are determined and recommendations are given.


 

 

 

 

 

Impact of volcanic ash plume aerosol on cloud microphysics Impact of volcanic ash plume aerosol on cloud microphysics

Date added: 03/19/2013
Date modified: 03/19/2013
Filesize: 3.41 MB

Martucci, M., J. Ovadnevaite, D. Ceburnis, H. Berresheim, S .Varghese, D. Martin, R. Flanagan, C. D. O'Dowd, Impact of volcanic ash plume aerosol on cloud microphysics., Atmos Environ, doi:10.1016/j.atmosenv.2011.12.033 , 2011


Abstract. This study focuses on the dispersion of the Eyjafjallajökull volcanic ash plume over the west of Ireland, at the Mace Head Supersite, and its influence on cloud formation and microphysics during one significant event spanning May 16th and May 17th, 2010. Ground-based remote sensing of cloud microphysics was performed using a Ka-band Doppler cloud RADAR, a LIDAR-ceilometer and a multi-channel microwave radiometer combined with the synergistic analysis scheme SYRSOC (Synergistic Remote Sensing Of Cloud). For this case study of volcanic aerosol interaction with clouds, cloud droplet number concentration (CDNC), liquid water content (LWC), and droplet effective radius (reff) and the relative dispersion were retrieved. A unique cloud type formed over Mace Head characterized by layer-averaged maximum, mean and standard deviation values of the CDNC, reff and LWC: Nmax = 948 cm-3, N = 297 cm-3, σN = 250 cm-3, reff max = 35.5 μm, reff = 4:8 μm, σreff = 4:4 μm, LWCmax =0:23 g m-3, LWC = 0:055 g m-3, σLWC =0:054 g m-3, respectively. The high CDNC, for marine clean air, were associated with large accumulation mode diameter (395 nm) and a hygroscopic growth factor consistent with sulphuric acid aerosol, despite being almost exclusively internally mixed in submicron sizes. Additionally, the Condensation Nuclei (CN, d > 10 nm) to Cloud Condensation Nuclei (CCN) ratio, CCN:CN ~1 at the moderately low supersaturation of 0.25%. This case study illustrates the influence of volcanic aerosols on cloud formation and microphysics and shows that volcanic aerosol can be an efficient CCN.

 

On condensation nuclei produced at heated surfaces On condensation nuclei produced at heated surfaces

Date added: 08/31/1959
Date modified: 07/03/2009
Filesize: 1.59 MB

O'Connor, T.C, Sharkey, W.P.F., and O Brolchain, C. (1959)- On condensation nuclei produced at heated surfaces, Geofisia pura e applicata, 42, 109-116.


Abstract

 

An investigation of heated surfaces of glass, metal and oil as sources of condensation nuclei is reported. Below a certain transition temperature the nucleus production is of a temporary nature and decreases to zero with the continued heating of the surface. Above this temperature, however, the nucleus production does not change with time. The transition temperature varies with the material of the surface and is not always associated with the onset of incandescence. The nuclei produced at the lower temperatures have a radius of about 10–5 cm and, on production, are mainly uncharged. Electric light bulbs can produce appreciable numbers of these nuclei.

In situ measurement of the ratio of aerosol absorption to extinction coefficient In situ measurement of the ratio of aerosol absorption to extinction coefficient

Date added: 07/31/1980
Date modified: 07/02/2009
Filesize: 558.49 kB

Bruce, C.W., Yee, Y.P., and Jennings, S.G. (1980)- In situ measurements of the ratio of aerosol absorption to extinction coefficients. Appl. Opt., 19, 1893-1894.


Abstract


A knowledge of the proportion of absorbed to scattered radiation for countermeasure smokes is necessary for modeling battlefield effects. Measurement of the total scattered component, however, is difficult. This report presents results obtained by using a new and simpler approach focussing on the extinction and the absorption coefficients (the total scattering coefficient is the difference quantity). Measurements of the absorption and extinction coefficients due to smoke produced by the combustion of 'red phosphorous' are simultaneously obtained in a small test chamber. The same CO2 laser beam at lambda = 9.55 micron is used to produce both results. A form of aerosol spectrophone cell was used to measure the absorption coefficient while functioning as a transmission cell from which the extinction coefficient was calculated. The ratio of the absorption to extinction coefficients was then compared with estimates of the same quantities based on calculated particle sizes, the particle size estimates being obtained from characteristics of the settling process. The ratio agreed with that predicted within the experimental error.

Estimating source regions of European emissions of trace gases from observations at Mace Head Estimating source regions of European emissions of trace gases from observations at Mace Head

Date added: 08/07/2001
Date modified: 07/27/2009
Filesize: 1004.2 kB

D.B. Ryall, R.G. Derwent, P.G. Simmonds, and S.J.O'Doherty. Estimating source regions of European emissions of trace gases from observations at Mace Head. Atmos. Environ. Vol 35, (2001), 2,507-25,23.


Abstract


A technique is described for identifying probable source locations for a range of greenhouse and ozone-depleting trace gases from the long-term measurements made at Mace Head, Ireland. The Met. Office's dispersion model NAME is used to predict concentrations at Mace Head from all possible sources in Europe, then source regions identified as those which consistently lead to elevated concentrations at Mace Head. Estimates of European emissions and their distribution are presented for a number of trace gases for the period 1995-1998. Estimated emission patterns are realistic, given the nature and varied applications of the species considered. The results indicate that whilst there are limitations, useful information about source distribution can be extracted from continuous measurements at a remote site. It is probable that much improved estimates could be derived if observations were available from a number of sites. The ability to assess emissions has obvious implications in monitoring compliance with internationally agreed quota and protocols.

 

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.

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

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

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


Abstract


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

 

EUCAARI: European Integrated project on Aerosol Cloud Climate and Air Quality interactions EUCAARI: European Integrated project on Aerosol Cloud Climate and Air Quality interactions

Date added: 04/28/2009
Date modified: 11/01/2009
Filesize: 670.53 kB

Kulmala, M., A. Asmi, H. K. Lappalainen, K. S. Carslaw, U. P¨oschl, U. Baltensperger, Ø. Hov, J.-L. Brenquier, S. N. Pandis, M. C. Facchini, H.-C. Hansson, A. Wiedensohler, and C. D. O’Dowd. Introduction: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – Integrating aerosol research from nano to global scales, Atmos. Chem. & Phys., 9, 2825-2841, 2009.


Abstract

 

The European Aerosol Cloud Climate and Air Quality Interactions project EUCAARI is an EU Research
Framework 6 integrated project focusing on understanding the interactions of climate and air pollution. EUCAARI works in an integrative and multidisciplinary way from nano to global scale. EUCAARI brings together several leading European research groups, state-of-the-art infrastructure and some key scientists from third countries to investigate the role of aerosol on climate and air quality. Altogether 48 partners from 25 countries are participating in EUCAARI.  
During the first 16 months EUCAARI has built operational systems, e.g. established pan-European measurement network for Lagrangian studies and four stations in developing countries. Also an improved understanding of nanoscale processes (like nucleation) has been implemented in global models. Here we present the research methods, organisation, operations and first results of EUCAARI.

Observation of diurnal cycles in short-lived tropospheric alkenes at a North Atlantic coastal s Observation of diurnal cycles in short-lived tropospheric alkenes at a North Atlantic coastal s

Date added: 08/05/1999
Date modified: 07/22/2009
Filesize: 210.82 kB

A. C. Lewis, J. B. McQuaid, N. Carslaw, M. J. Pilling, Diurnal cycles of short-lived tropospheric alkenes at a north Atlantic coastal site, Atmospheric EnvironmentVolume 33, Issue 15, , 1 July 1999, Pages 2417-2422.


Abstract


Observation of diurnal cycles in atmospheric concentrations of reactive alkenes are reported from measurements performed at a North Atlantic coastal site (Mace Head, Eire 53°19'34N; 9°54'14W). Species seen to exhibit distinct cycles included isoprene, ethene, propene, 1-butene, iso-butene and a substituted C6 alkene. Five hundred and thirty air mass classified measurements were performed over a 4 week period at approximately hourly frequency and demonstrate that during periods when air flow resulted from unpolluted oceanic regions a clear daily cycle in concentrations existed, peaking at around solar noon for all species. These observations support the proposed mechanism of production via photochemical degradation of organic carbon in sea water. The observed concentrations showed strong correlation (propene R2 > 0.75) with solar flux, with little relationship to other meteorological or chemical parameters. The species' short atmospheric lifetimes indicate that the source of emission was from local coastal waters within close proximity of the sampling site. At solar noon concentrations of reactive alkenes from oceanic sources were responsible for up to 88% of non-methane hydrocarbon reaction with the hydroxyl radical at this coastal marine site.

 

Micron-sized droplets irradiated with a pulsed CO2 laser measurement of explosion and breakdown thresholds Micron-sized droplets irradiated with a pulsed CO2 laser measurement of explosion and breakdown thresholds

Date added: 07/31/1990
Date modified: 07/03/2009
Filesize: 1.33 MB
Pinnick, R.G., Biswas, A., Armstrong, R.L., Jennings, S.G., Pendleton, J.D., and Fernandez, G. (1990). - Micron-sized droplets irradiated with a pulsed CO2 laser: Measurements of explosion and breakdown thresholds. Appl. Opt., 29, 918 - 925.

Abstract


Measurements of minimum CO2 laser fluence required to explode or disintegrate 10–60 µm radius droplets of water, ethanol, diesel (hexadecane), CCl4, bromoform, and ethyl bromide are reported. Threshold fluences range from 0.4 J cm-2 for 10-µm radius ethanol drops to 20 J cm-2 for 30µm bromoform drops. Threshold fluences for water droplets are ~3 J cm-2 independent of drop size. Comparison of the measurements to calculations of laser fluence required for considered absorbing droplets to reach superheat temperature is in good agreement for cases where liquid material properties are known, suggesting that superheating of droplets is the dominant mechanism causing explosion/disintegration. Measured droplet-induced laser breakdown thresholds are considerably higher than explosion thresholds and have less dependence on droplet size and composition. The highest breakdown threshold values are for water drops, which range from 150 to 280 J cm-2 (0.9–1.7 × 109W cm-2) compared with 670 J cm-2 (4.0 × 109 W cm-2) for clean air breakdown for the laser pulse length and spot size.

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.

Measurement and interpretation of OH and HO2 radicals during NAMBLEX Measurement and interpretation of OH and HO2 radicals during NAMBLEX

Date added: 08/06/2003
Date modified: 07/23/2009
Filesize: 8.76 kB
Lee, J.; Smith, S.; Bloss, W.; Heard, D.; Johnson, G.Measurement and interpretation of OH and HO2 radicals during NAMBLEX

Abstract

 

We present measurements of the hydroxyl, OH, and hydroperoxyl, HO2, radicals obtained during the summer 2002 North Atlantic Marine Boundary Layer Experiment at the Mace Head Atmospheric Research Station, Ireland. Direct  easurements
of [OH] were made using laser-induced fluorescence (LIF) at 308 nm, whilst measurements of [HO2] were made possible subsequent to chemical conversion to OH using NO. Calibration of the measurements of both species was carried out

using a technique based on the photolysis of H2O by a mercury lamp at 184.9 nm. Measurements of OH and HO2 were made on 24 and 13 days respectively, and the noon-time maxima in [OH] and [HO2] were found to vary between 3 - 8 x 10ˆ6 and 1.5 - 2.1 x 10ˆ8 molecule cm-3 respectively for j(O1D) in the range 0.5 - 2.2 x 10ˆ-5 s-1. There is significant evidence to support the presence of night-time HO2 radicals with concentrations in the range 2 - 3 x 10ˆ7 molecule cm-3 (mean [HO2] night-time detection limit 9.65 x 10ˆ6 molecule cm-3). The limited data available for [OH] at night suggest that there is some evidence for the presence of the species above its night-time detection limit (mean night-time [OH]  detection limit = 5.74 x 10ˆ4 molecule cm-3). The data set was used along with a wide range of supporting measurements to carry out a detailed study of chemistry in a range of clean and semi-polluted air masses. A strong correlation between [OH] and the rate of its primary production, P(OH), has been illustrated in both types of air mass with a reduction in dependence as [NOx] increases. A simple steady state calculation has also shown relatively good agreement highlighting the dominance of the CO and CH4 destruction routes in the Marine Boundary Layer (MBL). An analysis of the functional dependence of [OH], [HO2] and the ratio [HO2] / [OH] on [NOx] illustrated the non linear relationship between HOx and NOx radicals. Steady state modelling of [OH] versus [NOx] gave results within the error of the measurements. Similar modelling of [HO2] and [HO2] / [OH] versus [NOx] agreed well at higher [NOx], but showed discrepancies of increasing magnitude for [NOx] < 900 pptv. The effect of the reaction of halogen monoxide species (IO and BrO) with HO2 is also investigated. Observed levels of IO and BrO during NAMBLEX are such that the XO + HO2 reaction can account for up to 40 % of the total sink for HO2 radicals during clean marine air (low NOx) episodes, and to make a significant contribution to the production of OH via the photolysis of HOX.

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.

Measurements of the number concentration of aitken nuclei at mountain and rural sites Measurements of the number concentration of aitken nuclei at mountain and rural sites

Date added: 08/01/1975
Date modified: 07/03/2009
Filesize: 1.25 MB
Jennings, S.G.  (1975)- Measurements of condensation Aitken nuclei at rural and mountain sites. Jnl. de Rech. Atmos., No. 2,  59-66.

Abstract

 

A study of the number concentration at Aitken nuclei has been carried out using automated Nolan Pollak photoelectric nucleus ountain site, a sparsely populated site and in a rural envirorment. It has been found that the nucleus counter assembly operates very satisfactorily over long periods under field conditions.

The appuratus has proven to be particularly senstive in detecting pertubations in the background count due to localized nuclei sources. Frequency distribution curves of the individual observations follow closely a log-normal distribution for each measurement period. It is shown that te two minute sampling frequency can be increased by about an order of magnitude without causing a significant change in the nuclei number distribution.

Effect of instrumental particle sizing resolution on the modelling of aerosol radiative parameters Effect of instrumental particle sizing resolution on the modelling of aerosol radiative parameters

Date added: 03/04/2010
Date modified: 03/04/2010
Filesize: 886.14 kB

Chamaillard, K., S. G.  Jennings, D. Ceburnis, Y.J. Yoon and C. O’Dowd.  Effect of instrumental particle sizing resolution on the modelling of aerosol radiative parameters. doi:10.1016/j.jqsrt.2009.11.005, Journal of Quantitative Spectroscopy and Radiative Transfer Volume 111, Issue 5, 2010, Pages 753-771


 

 Abstract.

 

A more realistic estimation of the scattering and hemispheric backscattering coefficients, ssp and sbsp, and their respective optical cross section, Csca and Cbk, of aerosol particles is presented on the basis of the exact resolution of the width of the size bins of the particle counter instruments when size distribution measurements are used, and, with the exact optical detector instruments ability. The scattering and hemispheric back scattering cross sections, Csca and Cbk, of the particles are averaged over the full size bins of the particle counter instrument, while the sequantities are usually estimated only on the value of the mean geometric diameter of each size bin. Six instruments, the APS, ASASP-X, DMPS,FSSP-100, ELPI, and SMPS frequently used in particle size distribution measurements are reviewed, for spherical sea-salt particles at a wavelength l=0.55 mm. The comparison using the conventional geometric mean diameter versus the use of the full size bin leads to large amount of errors for the optical cross section with non-negligible effects on their respective optical coefficients.The maximal accuracy expected for these optical quantities depend on the particle diameter as well as on the channel width of the instruments, and are also function of the angular detector probe used to measure them..

 


Observations of iodine monoxide in the remote marine boundary layer Observations of iodine monoxide in the remote marine boundary layer

Date added: 08/06/2000
Date modified: 07/23/2009
Filesize: 584.58 kB

Allan B. J., G. McFiggans, J. M. C. Plane and H. Coe Observations of iodine monoxide in the remote marine boundary layer. J. Geophys. Res., 105, 14363-14369, 2000.


Abstract


We report measurements of the iodine monoxide (IO) radical in the marine boundary layer at three remote sites: Mace Head (Ireland), Tenerife (Canary Islands), and Cape Grim (Tasmania). IO was observed by long-path differential optical absorption spectroscopy using the A2Π3/2-X2Π3/2 electronic transition between 415 and 450 nm. The daytime IO concentration at these three locations was found to vary from below the detection limit (≤0.2 parts per trillion (ppt)) to a maximum of 4 ppt, with an average of about 1 ppt. Of particular note is that the IO observed off the north coast of Tenerife, which is probably typical of the open ocean sub-tropical North Atlantic, exhibited a distinct diurnal cycle which correlated strongly with the solar actinic flux in the near UV. IO was also observed at Cape Grim to be present at much lower levels (0.3 ppt) in westerly air from the Southern Ocean. As is shown in the companion paper (McFiggans et al., this issue), these measurements of IO are satisfactorily reproduced by a photochemical box model incorporating the recycling of iodine through marine aerosol. This model indicates that the direct iodine-catalyzed destruction of ozone in the boundary layer may well be similar to the losses caused by odd-hydrogen photochemistry and dry deposition. The significance of this work is that IO is probably present in much of the open ocean boundary layer, at levels where it may cause significant depletion of ozone.

 

 

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

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

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


Abstract


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

 

Measurements of Atmospheric Mercury Concentrations in Northwestern and Central Europe --- Comparison Measurements of Atmospheric Mercury Concentrations in Northwestern and Central Europe --- Comparison

Date added: 08/26/1995
Date modified: 07/23/2009
Filesize: 1.09 MB

R. Ebinghaus, H.H. Kock, S.G. Jennings, P. McCartin and M.J. Orren (1995): Measurements of Atmospheric Mercury Concentrations in Northwestern and Central Europe --- Comparison of Experimental Data and Model Results, Atmospheric Environment, Vol. 29, No. 22, pp. 3333 - 3344


Abstract


Field experiments were carried out at various sites in Europe to compare ambient air and precipitation concentrations of atmospheric mercury with model data. In addition, ozone and aerosol black carbon concentrations in air were measured simultaneously as input data for validation of the EMEP-based European long-range transport model. Data sets for mercury in air and precipitation, ozone and aerosol black carbon show that the selected sites range from background conditions for Northwestern Europe to regionally influenced air masses from heavily industrialized Central Europe. Measured 12 h averaged mercury concentrations in air range from 2.1 ng m-3 for Mace Head, Ireland to 8.2 ng m-3 for the Halle/Leipzig/Bitterfeld area in former German Democratic Republic. Precipitation concentrations of total mercury from 17 to 460 ng k-1 were measured from 1991 to 1993 for the same sites. Experimental data and model results for total gaseous mercury and mercury in precipitation are in good agreement.

Raindrop interactions and rainfall rates within clouds Raindrop interactions and rainfall rates within clouds

Date added: 11/30/1972
Date modified: 07/06/2009
Filesize: 787.75 kB

Brazier-Smith, P.R., Jennings, S.G., and Latham, J. (1973)- Raindrop interactions and rainfall rates within clouds. Quart. J. Roy. Met. Soc., 99, 260-272.


Abstract

 

Experiments showed that when a pair of water drops of raindrop dimensions collide and separate in air at their relative terminal velocities satellite drops are generally produced. Although the numbers and sizes of satellites resulting from individual interactions are highly variable a typical event produces about 3 satellites each having a volume of 0.04 ViVj/(Vi + Vj), where Vi and Vj are the volumes of the parent drops.

A full stochastic treatment is presented of the development of rainfall in a volume within a cloud where water is being released by condensation at a constant rate J. The production of satellites and an experimentally verified expression for the coalescence efficiency are incorporated into these calculations. Computations are made of the variation with time of the cloud water content, C, the rainwater content, L, the radar reflectivity, Z, the rainfall rate, P, and the drop-size distribution. The calculations show that the crucial parameter in governing the intensity and duration of rainfall is J, and that the microphysical processes are of secondary importance; C, L and P are all insensitive to and the production of satellite drops. The influence upon rainfall development of the break-up of large raindrops on attaining their maximum size within a cloud is found to be even less than that of the satellites.

The drop size distribution after several minutes of growth is insensitive to the initial spectrum but is markedly dependent upon and the production of satellites, which tend eventually to produce a bimodal spectrum. The radar reflectivity increases very rapidly with time (typically by about an order of magnitude every 2 1/2 minutes) and depends quite strongly on , but is unaffected by the production of satellites.


 

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).

Global trends and annual releases of CCl3F and CCl2F2 estimated from ALE GAGE and other measure Global trends and annual releases of CCl3F and CCl2F2 estimated from ALE GAGE and other measure

Date added: 08/07/1994
Date modified: 07/24/2009
Filesize: 1.87 MB

Cunnold, D. M., P. J. Fraser, R. F. Weiss, R. G. Prinn, P. G. Simmonds, B. R. Miller, F. N. Alyea, and A. J. Crawford (1994), Global trends and annual releases of CCl3F and CCl2F2 estimated from ALE/GAGE and other measurements from July 1978 to June 1991, J. Geophys. Res., 99(D1), 1107–1126.


Abstract


Thirteen years of Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment CCl3F and CCl2F2 measurements at five remote, surface, globally distributed sites are analyzed. Comparisons are made against shipboard measurements by the Scripps Institution of Oceanography group and archived air samples collected at Cape Grim, Tasmania, since 1978. CCl3F in the lower troposphere was increasing at an average rate of 9.2 ppt/yr over the period July 1978 to June 1988. CCl2F2 was increasing at an average 17.3 ppt/yr in the lower troposphere over the same period. However, between July 1988 and June 1991 the increases of CCl3F and CCl2F2 in this region have averaged just 7.0 ppt/yr and 15.7 ppt/yr, respectively. The rate of increase has been decreasing 2.4 ppt/yr2 and 2.9 ppt/yr2 over this 3-year period. Based on a recent scenario of the global releases of these compounds and using the new calibration scale SIO 1993, the equilibrium lifetimes are estimated to be 44 - 10 + 17 and 180 - 81 + 820 years for CCl3F and CCl2F2, respectively. Using these lifetime estimates and a two-dimensional model, it is estimated that global releases of these two chlorofluorocarbons in 1990 were 249 ± 28 × 106 kg for CCl3F and 366 ± 30 × 106 kg for CCl2F2. It is also estimated that combined releases of these chlorofluorocarbons in 1990 were 21 ± 5% less than those in 1986.

 

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 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.

Chemical ionization mass spectrometer for long-term measurements of atmospheric OH and H2SO4 Chemical ionization mass spectrometer for long-term measurements of atmospheric OH and H2SO4

Date added: 07/27/2000
Date modified: 07/27/2009
Filesize: 522 kB

Berresheim, H., T. Elste, C. Plass-Dulmer, F. L. Eisele and D. J. Tanner (2000). Chemical ionization mass spectrometer for long-term measurements of atmospheric OH and H2SO4. International Journal of Mass Spectrometry 202 (1-3): 91-109.

 


Abstract


An atmospheric pressure/chemical ionization mass spectrometer (AP/CIMS) has been developed for continuous long-term
measurements of atmospheric OH and H2SO4. The corresponding methods both involve chemical ionization of H2SO4 by NO3-
ions with OH being first titrated by excess SO2 to form equivalent concentrations of H2SO4 in the system. The chemical
ionization mass spectrometry (CIMS) system has been operated since April 1998 at the Meteorological Observatory
Hohenpeissenberg, a mountain research station of the German Weather Service in South Germany. A technical description of
the apparatus is presented followed by a detailed estimate of uncertainties in calibration and ambient air measurements
resulting from changes in instrumental and/or ambient parameters. Examples from both calibration runs and ambient air
measurements are shown. For the present system and operating conditions accuracy, precision, and detection limit are
estimated to be 39%, 30%, and 3 3 104 molecules cm23 for H2SO4, and 54%, 48%, and 5 3 105 molecules cm23 for OH
measurements, respectively, based on 5 min signal integration. (Int J Mass Spectrom 202 (2000) 91–109) © 2000 Elsevier
Science B.V.

Regional climate model simulations of North Atlantic cyclones frequency and intensity changes Regional climate model simulations of North Atlantic cyclones frequency and intensity changes

Date added: 08/01/2008
Date modified: 07/23/2009
Filesize: 4.19 MB
Semmler, T., S. Varghese, R. McGrath, P. Nolan, S. Wang, P. Lynch, and C. O'Dowd (2008) 'Regional climate model simulations of North Atlantic cyclones: frequency and intensity changes'. Climate Research, 36 :1-16.

Abstract


Frequency and intensity of cyclones over the North Atlantic are investigated using 2 data sets from simulations with the Rossby Centre regional climate model RCA3. The model domain comprises large parts of the North Atlantic and the adjacent continents. RCA3 is driven by ECHAM5- OM1 general circulation model data for May to December from 1985 to 2000 and May to December from 2085 to 2100 assuming the SRES-A2 emission scenario. We apply an objective algorithm to identify and track tropical and extratropical cyclones, as well as extratropical transition. The simulation indicates increase in the count of strong hurricanes and extratropical cyclones. Contrasting, and generally weaker, changes are seen for the less extreme events. Decreases of 18% in the count of extratropical cyclones and 13% in the count of tropical cyclones with wind speeds of ≥18 m s–1 can be found. Furthermore, there is a pronounced shift in the tracks of hurricanes and their extratropical transition in November and December—more hurricanes are seen over the Gulf of Mexico, the Caribbean Sea and the western Sargasso Sea and less over the southern North Atlantic.

Dimethyl sulfide and its oxidation products in the atmosphere of the Atlantic and Southern Ocea Dimethyl sulfide and its oxidation products in the atmosphere of the Atlantic and Southern Ocea

Date added: 08/06/1996
Date modified: 07/23/2009
Filesize: 823.17 kB

Davison, B., C.D. O'Dowd, C.N. Hewitt, M.H. Smith, R.M. Harrison, D.A. Peel, E. Wolf, R. Mulvaney, M. Schwikowski and U. Baltensperger, Dimethyl Sulfide and its Oxidation Products in the Atmosphere of the Atlantic and Southern Oceans, Atmos. Environ., 30, 1895-1906, 1996


Abstract


Dimethyl sulfide, methane sulfonate, non-sea-salt sulfate and sulfur dioxide concentrations in air were obtained during a cruise between the U.K. and the Antarctic during the period October 1992-January 1993. In equatorial regions (30°N to 30°S) the atmospheric DMS concentration ranged from 3 to 46 ng (S)m-3 with an average of 18 ng(S)m-3. In the polar waters and regions south of the Falkland Islands concentrations from 3 to 714 ng(S)m-3 were observed with a mean concentration of 73 ng(S)m-3. Methane sulfonate concentrations were also enhanced in the vicinity of the Antarctic Peninsula and in the Weddell Sea. A simple model of DMS oxidation was used to estimate the ocean to atmosphere flux rate, and this was found to be within the range of previous estimates, with a mean value of 1011 ng (S) m-2 h-1.

 

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.

 

Concurrent observations of alkyl halides and dimethyl sulphide in marine air Implications for s Concurrent observations of alkyl halides and dimethyl sulphide in marine air Implications for s

Date added: 08/05/1999
Date modified: 07/27/2009
Filesize: 560.08 kB

Bassford, M.R., G. Nickless, P. Simmonds, A.C. Lewis, M.J. Pilling, M.J. Evans and J.A. Pyle, Concurrent observations of alkyl halides and dimethyl sulphide in marine air: Implications for sources of atmospheric methyl iodide, Atmos Environ, 33, 2373-2383, 1999, (Ser. No. ACP106).


Abstract


Continuous atmospheric measurements of methyl iodide and dimethyl sulphide were carried out at Mace Head, western Ireland, over a 4-week period in July 1996. The concurrent observations of methyl iodide and dimethyl sulphide reported here display a clear association, indeed statistical analysis indicated a very signiÞcant degree of covariance. A simple yet informative use of modelled 5-day back trajectories was employed in tandem with examination of local meteorology to illuminate the geographical source regions of methyl iodide and dimethyl sulphide. The  interpretation of the atmospheric observations in terms of air-mass ßow has elucidated part of the global methyl iodide cycle and provides evidence for two distinct source regions of methyl iodide:
1. Under certain synoptic meteorological conditions, long-range transport of methyl iodide and dimethyl sulphide was observed from discrete areas of the sub-tropical Atlantic Ocean located in a region between 30Ð50¡N and 20Ð50¡W.

2. Measurements taken under di¤erent conditions led us to believe that there was an additional source of methyl iodide that inßuenced the Mace Head atmosphere, most likely produced by coastal macroalgae which inhabit waters o¤ the western coast of Ireland.

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.

 

Physical Characteristic of the Ambient Aerosol At Macehead Physical Characteristic of the Ambient Aerosol At Macehead

Date added: 07/31/1991
Date modified: 07/23/2009
Filesize: 3.29 MB

Jennings, S.G., O'Dowd, C.D., O'Connor, T.C., and McGovern, F.M (1991). - Physical characteristics of the ambient aerosol at Mace Head. Atmos. Environ., 25A, 557 - 562.


Abstract


This paper describes results of a reasonably extensive series of ambient aerosols measurements conducted for the first time from MAce HEad, on the west coast of Ireland. Aerosol size distributions (0.045 <radius,r, <1.5 micrometres (Um)) And Basic meteorological parameters were measured under both maritime, modified maritime and continental air mass conditions. It was found that the shape of the size distribution spectra is dependent on air mass source

Measurements of fractionated gaseous mercury concentrations over northwestern and central Europ Measurements of fractionated gaseous mercury concentrations over northwestern and central Europ

Date added: 08/05/1999
Date modified: 07/23/2009
Filesize: 215.76 kB
Sommar, J., Feng, X., Gardfeldt, K. and Lindqvist, O., 1999. Measurements of fractionated gaseous mercury concentrations in northwestern and central Europe, 1995–99. Journal of Environmental Monitoring 1, pp. 435–439.

Abstract


Although it makes up only a few per cent. of total gaseous mercury (TGM) in the atmosphere, the fraction of xidised (divalent) mercury plays a major role in the biogeochemical cycle of mercury due to its high affinity for water and surfaces. Quantitative knowledge of this fraction present in mixing ratios in the parts-per-1015 (ppq) range is currently very scarce. This work is based on #220 data for divalent gaseous mercury (DGM) collected during 1995–99 in ambient air. Over the course of the measurements, the sampling and analytical methods were modified and improved. This is described here in detail and includes transition from wet leaching and reduction procedures to thermo-reductive desorption, the use of annular as well as tubular denuders and adoption of an automated sampling system. The concentration of DGM exhibited a strong seasonal behaviour in contrast to atomic gaseous mercury, with low values in winter and maximum values in summer. The DGM/TGM ratios were frequently found to be below the detection limit (1%) and in the range 1–5%. A trend of diurnal DGM patterns was observed and implies photolytically induced sources. Scavenging of DGM during rain events was also noticed.

 

Combination coefficients of small positive ions with sub micrometer aerosol particles Combination coefficients of small positive ions with sub micrometer aerosol particles

Date added: 02/14/1978
Date modified: 07/01/2009
Filesize: 745.64 kB

Dixon, A.M., and Jennings, S.G. (1978).- Combination coefficients of small ions with submicrometre aerosol particles. J. Phys. D: Appl. Phys., 11, 125-136.


Abstract


The work was concerned with the simultaneous measurement of the combination coefficients b and eta 0, between small ions and aerosol particles, and between small ions and uncharged aerosol particle respectively, for different particle radii. The ion-ion mutual repulsion coefficient gamma had a mean experimental value of 2.39 (+or-0.14)*10-6 cm3 s-1. The decay of ions in the presence of aerosol particles in a mylar vessel was recorded and compared with a family of computed theoretical ion-aerosol decay curves to determine b. eta 0 could then be determined from concentration of uncharged nuclei present. Satisfactory agreement was found between the b eta 0 versus radius results and various theoretically computed values. Possible reasons for discrepancies between theory and experiment are indicated.

In situ chloroform measurements at Advanced Global Atmospheric Gases Experiment atmospheric research stations from 1994 to 1998 In situ chloroform measurements at Advanced Global Atmospheric Gases Experiment atmospheric research stations from 1994 to 1998

Date added: 08/01/2001
Date modified: 07/24/2009
Filesize: 1.54 MB
O'Doherty, S., et al. (2001), In situ chloroform measurements at Advanced Global Atmospheric Gases Experiment atmospheric research stations from 1994 to 1998, J. Geophys. Res., 106(D17), 20,429–20,444.

Abstract


Measurements of atmospheric chloroform (CHCl3) by in situ gas chromatography using electron capture detection are reported from the Advanced Global Atmospheric Gases Experiment (AGAGE) network of atmospheric research stations. They are some of the most comprehensive in situ, high-frequency measurements to be reported for CHCl3 and provide valuable information not only on clean “baseline” mixing ratios but also on local and regional sources. Emissions from these sources cause substantial periodic increases in CHCl3 concentrations above their baseline levels, which can be used to identify source strengths. This is particularly the case for measurements made at Mace Head, Ireland. Furthermore, these local sources of CHCl3 emissions are significant in relation to current estimates of global emissions and illustrate that the understanding of competing sources and sinks of CHCl3 is still fragmentary. These observations also show that CHCl3 has a very pronounced seasonal cycle with a summer minimum and winter maximum presumably resulting from enhanced destruction by OH in the summer. The amplitude of the cycle is dependent on sampling location. Over the 57 months of in situ measurements a global average baseline concentration of 8.9±0.1 ppt was determined with no appreciable trend in the baseline detected.

Comparisons of box model calculations and measurements of formaldehyde from the 1997 North Atlantic Comparisons of box model calculations and measurements of formaldehyde from the 1997 North Atlantic

Date added: 08/31/2002
Date modified: 07/01/2009
Filesize: 953.85 kB
Frost, G. J., et al. (2002), Comparisons of box model calculations and measurements of formaldehyde from the 1997 North Atlantic Regional Experiment, J. Geophys. Res., 107(D8), 4060, doi:10.1029/2001JD000896.

Abstract


Formaldehyde (CH2O) measurements from two independent instruments are compared with photochemical box model calculations. The measurements were made on the National Oceanic and Atmospheric Administration P-3 aircraft as part of the 1997 North Atlantic Regional Experiment (NARE 97). The data set considered here consists of air masses sampled between 0 and 8 km over the North Atlantic Ocean which do not show recent influence from emissions or transport. These air masses therefore should be in photochemical steady state with respect to CH2O when constrained by the other P-3 measurements, and methane oxidation was expected to be the predominant source of CH2O in these air masses. For this data set both instruments measured identical CH2O concentrations to within 40 parts per trillion by volume (pptv) on average over the 0–800 pptv range, although differences larger than the combined 2σ total uncertainty estimates were observed between the two instruments in 11% of the data. Both instruments produced higher CH2O concentrations than the model in more than 90% of this data set, with a median measured-modeled [CH2O] difference of 0.13 or 0.18 ppbv (depending on the instrument), or about a factor of 2. Such large differences cannot be accounted for by varying model input parameters within their respective uncertainty ranges. After examining the possible reasons for the model-measurement discrepancy, we conclude that there are probably one or more additional unknown sources of CH2O in the North Atlantic troposphere.

High Electric fields from industrial stack plumes High Electric fields from industrial stack plumes

Date added: 01/01/1976
Date modified: 07/02/2009
Filesize: 338.61 kB

Jennings, S.G., and Jones, C.D. (1976)- High electric fields due to industrial stack plumes. Nature, 264, 236-237.


Abstract


THE use of electrostatic precipitators on an industrial stack to remove particulate matter and aerosol particles is now quite common. The plume emanating from such an installation is likely to be highly electrically charged, and consequently associated electrical effects should be observable downwind of the stack.

European source strengths and Northern Hemisphere baseline concentrations of radiatively active European source strengths and Northern Hemisphere baseline concentrations of radiatively active

Date added: 08/07/1998
Date modified: 07/24/2009
Filesize: 339.88 kB

Derwent, RG, Simmonds, PG, O'Doherty, S, et al , European source strengths and northern hemisphere baseline concentrations of radiatively active trace gases at Mace Head, Ireland, ATMOS ENVIRON, 1998, Vol: 32, Pages: 3703 - 3715, ISSN: 1352-2310


Abstract


Greenhouse gas measurements have been made continuously with high frequency and precision at the remote baseline monitoring station at Mace Head on the Atlantic Ocean coastline of Ireland since 1987. By using three independent methods, the two-hourly observations have been sorted by air mass origins into those from unpolluted' or Northern Hemisphere baseline air masses and those from polluted European air masses. Northern Hemisphere baseline methane, nitrous oxide and carbon dioxide concentrations have risen throughout the 10 year period and their respective mid-1996 levels are the highest mid-year levels recorded so far. For ozone, the mid-1996 annual mean concentrations was within 0.1 ppb of the highest mid-year level. The elevated greenhouse gas concentrations found in polluted air masses provide clear evidence for the presence of substantial emission sources in Europe. Using a simple climatological long-range transport model and a sophisticated Lagrangian dispersion model, it has been possible to estimate the magnitudes of the greenhouse gas emissions required to support the observations. Estimates of European source strengths of methane, nitrous oxide, carbon monoxide and halocarbons agree well with the available emission inventories. Using the Mace Head observations, significant additional contributions to global climate change have been identified from the trace gases: methane, nitrous oxide and tropospheric ozone, over and above that driven by carbon dioxide. The radiative forcing consequences of a range of HCFCs and HFCs will only become of significance should their emissions grow to become comparable with those of the CFCs that they have replaced.

 

Overview of the synoptic and pollution situation over Europe during the EUCAARI-LONGREX field campai Overview of the synoptic and pollution situation over Europe during the EUCAARI-LONGREX field campai

Date added: 02/07/2011
Date modified: 02/07/2011
Filesize: 2.98 MB

Hamburger, T., G. McMeeking, A. Minikin, W. Birmili, M. Dall’Osto, C. O’Dowd, H. Flentje, B. Henzing, H. Junninen, A. Kristensson, G. de Leeuw, A. Stohl, J. F. Burkhart, H. Coe, R. Krejci, and A. Petzold



 

Abstract. In May 2008 the EUCAARI-LONGREX aircraft field campaign was conducted within the EUCAARI intensive observational period. The campaign aimed at studying the distribution and evolution of air mass properties on a continental scale. Airborne aerosol and trace gas measurements were performed aboard the German DLR Falcon 20 and the British FAAM BAe-146 aircraft. This paper outlines the meteorological situation over Europe during May 2008 and the temporal and spatial evolution of predominantly anthropogenic particulate pollution inside the boundary layer and the free troposphere. Time series data of six  selected ground stations are used to discuss continuous measurements besides the single flights. The observations encompass total and accumulation mode particle number concentration (0.1–0.8 μm) and black carbon mass concentration as well as several meteorological parameters. Vertical profiles of total aerosol number concentration up to 10 km are compared to vertical profiles probed during previous studies.During the first half of May 2008 an anticyclonic blocking event dominated the weather over Central Europe. It led to increased pollutant concentrations within the centre of the high pressure inside the boundary layer. Due to long-range transport the accumulated pollution was partly advected towards Western and Northern Europe. The measured aerosol number concentrations over Central Europe showed in the boundary layer high values up to 14 000 cm−3 for particles in diameter larger 10 nm and 2300 cm−3 for accumulation mode particles during the high pressure period, whereas the middle free troposphere showed rather low concentrations of particulates. Thus a strong negative gradient of aerosol concentrations between the well mixed boundary layer and the clean middle troposphere occurred.

European Emissions of HFC-365mfc, a Chlorine-Free Substitute for the Foam Blowing Agents HCFC-141b and CFC-11 European Emissions of HFC-365mfc, a Chlorine-Free Substitute for the Foam Blowing Agents HCFC-141b and CFC-11

Date added: 08/05/2007
Date modified: 07/24/2009
Filesize: 595.17 kB

European Emissions of HFC-365mfc, a Chlorine-Free Substitute for the Foam Blowing Agents HCFC-141b and CFC-11
Stemmler, K., Folini, D., Ubl, S., Vollmer, M.K., Reimann, S., O'Doherty, S., Greally, B.R., Simmonds, P.G., and Manning, A.J. Environ. Sci. Technol., 41, 4, 1145 - 1151, 2007,  10.1021/es061298h


Abstract


HFC-365mfc (1,1,1,3,3-pentafluorobutane) is an industrial chemical used for polyurethane foam blowing. From early 2003, HFC-365mfc has been commercially produced as a substitute for HCFC-141b, whose use in Europe has been banned since January 2004. We describe the first detection of HFC-365mfc in the atmosphere and report on a 2 year long record at the high Alpine station of Jungfraujoch (Switzerland) and the Atlantic coast station of Mace Head (Ireland). The measurements at Jungfraujoch are used to estimate the central European emissions of HFC-365mfc, HCFC-141b, and CFC-11. For HFC-365mfc, we estimate the central European emissions (Germany, France, Italy, Switzerland, The Netherlands, Belgium, and Luxembourg) in 2003 and 2004 as 400-500 tonnes year-1. These emissions are about one-third lower on a per capita basis than what we estimate from the Mace Head measurements for the total of Europe. The estimated emissions of HCFC-141b for central Europe are higher (i.e., 7.2-3.5 ktonnes year-1) with a decreasing trend in the period from 2000 to 2004. Residual emissions of CFC-11 are estimated at 2.4-4.7 ktonnes year-1 in the same time period. The Po Valley (northern Italy) appears to be a main source region for HFC-365mfc and for the former blowing agents HCFC-141b and CFC-11. In 2004, the emissions of HFC-365mfc arose from a wider region of Europe, which we attribute to an increased penetration of HFC-365mfc into the European market.

Marine aerosols and iodine emissions Marine aerosols and iodine emissions

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

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


Abstract


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

Evaluation of a Lagrangian box model using field measurements from EASE (Eastern Atlantic Summe Evaluation of a Lagrangian box model using field measurements from EASE (Eastern Atlantic Summe

Date added: 08/07/2000
Date modified: 07/24/2009
Filesize: 696.19 kB

Evans, M.J., D.E. Shallcross, K.S. Law, J.O.F. Wild, P.G. Simmonds, T.G. Spain, P. Berrisford, J. Methven, A.C. Lewis, J.B. McQuaid, M.J. Pilling, B.J. Bandy, S.A. Penkett, and J.A. Pyle, Evaluation of a Lagrangian box model using field measurements from EASE 1996, Atmos. Environ., 34, 3843-3863, 2000, (Ser. No. ACP048).


Abstract


The Cambridge Tropospheric Trajectory model of Chemistry and Transport (CiTTyCAT), a Lagrangian chemistry model, has been evaluated using atmospheric chemical measurements collected during the East Atlantic Summer Experiment 1996 (EASE '96). This field campaign was part of the UK Natural Environment Research Council's (NERC) Atmospheric Chemistry Studies in the Oceanic Environment (ACSOE) programme, conducted at Mace Head, Republic of Ireland, during July and August 1996. The model includes a description of gas-phase tropospheric chemistry, and simple parameterisations for surface deposition, mixing from the free troposphere and emissions. The model generally compares well with the measurements and is used to study the production and loss of O3 under a variety of conditions. The mean difference between the hourly O3 concentrations calculated by the model and those measured is 0.6 ppbv with a standard deviation of 8.7 ppbv. Three specific air-flow regimes were identified during the campaign - westerly, anticyclonic (easterly) and south westerly. The westerly flow is typical of background conditions for Mace Head. However, on some occasions there was evidence of long-range transport of pollutants from North America. In periods of anticyclonic flow, air parcels had collected emissions of NOx and VOCs immediately before arriving at Mace Head, leading to O3 production. The level of calculated O3 depends critically on the precise details of the trajectory, and hence on the emissions into the air parcel. In several periods of south westerly flow, low concentrations of O3 were measured which were consistent with deposition and photochemical destruction inside the tropical marine boundary layer.

 

Particle size dependent response of aerosol counters Particle size dependent response of aerosol counters

Date added: 08/01/2002
Date modified: 07/03/2009
Filesize: 652.99 kB
Ankilov, A., A Baklanov, M. Colhoun, K-H. Enderle, J. Gras, Yu Jualanov, D. Kaller, A. Linder, A.A. Lushnikov, R. Mavliev, F. McGovern, T.C. O'Connor, J. Podzimek, O. Prining, G.P. Reischl, R. Rudolf, G.J. Sem, W.W. Szymanski, E. Tamm, A.E. Vrtala, P.E. Wagner, W. Winklmayr and V. Zagaynov, Particle size dependent response of aerosol particle counters, Atmos. Res., 62, 209-238, 2002.

Abstract


During an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (IAMAS-IUGG), 10 instruments for aerosol number concentration measurement were studied, covering a wide range of methods based on various different measuring principles. In order to investigate the detection limits of the instruments considered with respect to particle size, simultaneous number concentration measurements were performed for monodispersed aerosols with particle sizes ranging from 1.5 to 50 nm diameter and various compositions.

The instruments considered show quite different response characteristics, apparently related to the different vapors used in the various counters to enlarge the particles to an optically detectable size. A strong dependence of the 50% cutoff diameter on the particle composition in correlation with the type of vapor used in the specific instrument was found. An enhanced detection efficiency for ultrafine hygroscopic sodium chloride aerosols was observed with water operated systems, an analogous trend was found for n-butanol operated systems with nonhygroscopic silver and tungsten oxide particles.

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