Payday loans
Home Publications Journal Publications

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.

Click on the "Search Document" icon above to find a publication based on the search criteria you create.

 


Documents

Order by : Name | Date | Hits [ Descendent ]

Free-radical chemistry in the coastal marine boundary layer Measurements and modelling at Mace Free-radical chemistry in the coastal marine boundary layer Measurements and modelling at Mace

Date added: 08/06/2003
Date modified: 07/24/2009
Filesize: 21.42 kB

D. E. Heard et al. (NAMBLEX team), "Free-radical chemistry in the coastal marine boundary layer: Measurements and modelling at Mace Head, Ireland, during the NAMBLEX campaign", Geophysical Research Abstracts, European Geophysical Society, 5, 11843 (2003).


Abstract


The coastal marine boundary layer provides an ideal location to study the background chemistry of the remote troposphere, and also the effects of perturbations due to biogenic emissions from the inter-tidal zone. The North Atlantic Marine Boundary Layer EXperiment (NAMBLEX), involving ca. 50 scientists, took place at the Mace Head Atmospheric Research Station in July--September 2002. Measurements were made of a number of free-radical species, including OH, HO_2 and RO_2, together with a comprehensive suite of supporting measurements of longer-lived species and radiative parameters that define their rates of formation and destruction. This paper focuses on a comparison of the concentrations of OH and HO_2, measured using laser-induced fluorescence at low pressure, and RO_2, measured using a dual-channel peroxy radical amplifier, under predominantly clean westerly conditions ([NO] < 20 pptv), but also during polluted episodes. Full diurnal profiles were measured on a large number of days, allowing a detailed analysis of the correlations between the free-radical concentrations and the controlling variables, for example, J(O^1D), NO_x and VOCs. A zero-dimensional model, based on the Master Chemical Mechanism (v3), and constrained by measurements of CO, CH_4, H_2, O_3, H_2O, speciated non-methane hydrocarbons, oxygenated hydrocarbons, peroxides, HCHO, NO, NO-2, photolysis frequencies (determined using a scanning spectral-radiometer) and temperature, is used to calculate OH, HO_2 and RO_2. A comparison between measured and calculated levels of free-radicals is made over a range of NO levels. Agreement for OH is better than in previous campaigns at Mace Head. The destruction of OH is dominated by reaction with CO (> 50%), but reaction with the previously unmeasured oxygenated VOCs (in particular acetaldehyde) is found to be more important than reaction with CH_4 or NMHC, with significant implications for the chemistry of the marine boundary layer.

Functionalization and fragmentation during ambient organic aerosol aging: application of the 2-D volatility basis set to field studies Functionalization and fragmentation during ambient organic aerosol aging: application of the 2-D volatility basis set to field studies

Date added: 03/21/2013
Date modified: 03/21/2013
Filesize: 1.84 MB

Murphy, B. N., N. M. Donahue, C. Fountoukis, M. Dall’Osto, C. O’Dowd, A. Kiendler-Scharr, and S. N. Pandis, Functionalization and fragmentation during ambient organic aerosol aging: application of the 2-D volatility basis set to field studies, Atmos. Chem. Phys., 12, 10797–10816, 2012, doi:10.5194/acp-12-10797-2012.


Abstract. Multigenerational oxidation chemistry of atmospheric organic compounds and its effects on aerosol loadings and chemical composition is investigated by implementing the Two-Dimensional Volatility Basis Set (2-D-VBS) in a Lagrangian host chemical transport model. Three model formulations were chosen to explore the complex interactions between functionalization and fragmentation processes during gas-phase oxidation of organic compounds by the hydroxyl radical. The base case model employs a conservative transformation by assuming a reduction of one order of magnitude in effective saturation concentration and an increase of oxygen content by one or two oxygen atoms per oxidation generation. A second scheme simulates functionalization in more detail using group contribution theory to estimate the effects of oxygen addition to the carbon backbone on the compound volatility. Finally, a fragmentation scheme is added to the detailed functionalization scheme to create a functionalization-fragmentation parameterization. Two condensed-phase chemistry pathways are also implemented as additional sensitivity tests to simulate (1) heterogeneous oxidation via OH uptake to the particle-phase and (2) aqueous-phase chemistry of glyoxal and methylglyoxal. The model is applied to summer and winter periods at three sites where observations of organic aerosol (OA) mass and O:C were obtained during the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) campaigns. The base case model reproduces observed mass concentrations and O:C well, with fractional errors (FE) lower than 55% and 25 %, respectively. The detailed functionalization scheme tends to overpredict OA concentrations, especially in the summertime, and also underpredicts O:C by approximately a factor of 2. The detailed functionalization model with fragmentation agrees well with the observations for OA concentration, but still underpredicts O:C. Both heterogeneous oxidation and aqueous-phase processing have small effects on OA levels but heterogeneous oxidation, as implemented here, does enhance O:C by about 0.1. The different schemes result in very different fractional attribution for OA between anthropogenic and biogenic sources.

 

Further Measurements Of Global Radiation Using Black And White Atmometers Further Measurements Of Global Radiation Using Black And White Atmometers

Date added: 08/07/1957
Date modified: 07/01/2009
Filesize: 522.76 kB
TC O Connor, Further Measurements Of Global Radiation Using Black And White Atmometers, Geofisica Pura E Apllicata- Milano Vol 38 pp 154-157 (1957)

Abstract

 

The feasibility of using the difference in the evaporation from a black and whiteatmometer for the continuous routine measurement of global radiation at a field station was examined. The atmometers were operated continously for 177 days and the results obtained were compared with measurements of the global radiation for the corresponding period as given by a Bellani pyranometer. Good agreement between the monthly totals of global radiation from both methods were obtained

GAGE/AGAGE measurements indicating reductions in global emissions of CCl3F and CCl2F2 in 1992–1994 GAGE/AGAGE measurements indicating reductions in global emissions of CCl3F and CCl2F2 in 1992–1994

Date added: 08/01/1997
Date modified: 07/24/2009
Filesize: 1.36 MB
Cunnold, D. M., R. F. Weiss, R. G. Prinn, D. Hartley, P. G. Simmonds, P. J. Fraser, B. Miller, F. N. Alyea, and L. Porter (1997), GAGE/AGAGE measurements indicating reductions in global emissions of CCl3F and CCl2F2 in 1992–1994, J. Geophys. Res., 102(D1), 1259–1269.

Abstract


Global Atmospheric Gases Experiment/Advanced GAGE (GAGE/AGAGE) observations of CCl3F indicate that global concentrations of this compound reached a maximum in 1993 and decayed slightly in 1994; CCl2F2 concentrations increased approximately 7 ppt in both 1993 and 1994. The observations suggest that world emissions in these two years were smaller than industry production figures would suggest and have decreased faster than expected under the Montreal Protocol and its amendments. An analysis of regional pollution events at the Mace Head site suggest that industry may be underestimating the decline of emissions in Europe. It is argued, however, that the decline in European emissions is not biasing the background Mace Head measurements (or the GAGE global averages). Combining the chlorofluorocarbon measurements, including CCl2FCClF2, with GAGE/AGAGE measured global decreases in CH3CCl3 and CCl4 after 1992 and with Cape Grim archived air measurements of CHClF2, the measurements suggest that anthropogenic atmospheric chlorine loading from these six gases maximized in 1992 at 2.95 ± 0.04 ppb and that it had decreased by 0.02 ± 0.01 ppb by the beginning of 1995.

Gas-Aerosol Relationships of OH, H2SO4, and MSA Observations in the Coastal Marine Boundary Layer at Mace Head Gas-Aerosol Relationships of OH, H2SO4, and MSA Observations in the Coastal Marine Boundary Layer at Mace Head

Date added: 07/31/2002
Date modified: 07/27/2009
Filesize: 542.87 kB
H. Berresheim, T. Elste, H.G. Tremmel, C O'Dowd, A.Allen, H.C. Hansson, K Rosman, M. dal Maso, J. Makela, and Markku Kulmala. Gas-Aerosol Relationships of OH, H2SO4, and MSA: Observations in the Coastal Marine Boundary Layer at Mace Head, Ireland. J. Geophys. Res., 107, 10.1029/2000JD000229, 2002.

Abstract

 

Atmospheric concentrations of gaseous sulfuric acid (H2SO4), methane sulfonic acid (MSA), and hydroxyl radicals (OH) were measured by chemical ionization mass spectrometry (CIMS) during the second New Particle Formation and Fate in the Coastal Environment (PARFORCE) campaign in June 1999 at Mace Head, Ireland. Overall median concentrations in marine background air were 1.5, 1.2, and 0.12 × 106 cm−3, respectively. H2SO4 was also present at night indicating significant contributions from nonphotochemical sources. A strong correlation was found between daytime OH and H2SO4 levels in clean marine air suggesting a fast local production of H2SO4 from sulfur precursor gases. Steady state balance calculations of ambient H2SO4 levels agreed with measured concentrations if either very low H2SO4 sticking coefficients (0.02–0.03) or sources in addition to the SO2 + OH reaction were assumed. Overall, variations in ambient H2SO4 levels showed no correlation with either the tidal cycle or ultrafine particle (UFP) concentrations. However, on particular days an anticorrelation between H2SO4 and UFP levels was occasionally observed providing evidence for the contribution of H2SO4 to new particle formation and/or particle growth. Gaseous MSA concentrations were inversely correlated with dew point temperature reflecting a highly sensitive gas-particle partitioning equilibrium of this compound. The present observations seriously question the general use of MSA as a conservative tracer to infer the relative production yield of H2SO4 from dimethylsulfide (DMS) oxidation. MSA/H2SO4 concentration ratios typically ranged between 0.06 and 1.0 in marine air at ground level. Measured diel OH profiles showed a significant deviation from concurrent variations of the ozone photolysis frequency. They also showed up to 1 order of magnitude lower values compared to OH concentrations calculated with a simple photochemical box model. These differences were most pronounced during particle nucleation events occurring on sunny days around noon and at low tide. The present results suggest that both the oxidation capacity and the particle formation potential in the coastal boundary layer were significantly affected by reactions of unknown compounds prevailing in this type of environment.

Gas-to-particle conversion of sulphur and nitrogen compounds as studied at marine stations in N Gas-to-particle conversion of sulphur and nitrogen compounds as studied at marine stations in N

Date added: 08/05/1996
Date modified: 07/02/2009
Filesize: 935.92 kB

V. L. Foltescu, E. Selin Lindgren, J. Isakson, M. Oblad, J. M. Pacyna, S. Benson, Gas-to-particle conversion of sulphur and nitrogen compounds as studied at marine stations in Northern Europe, Atmospheric EnvironmentVolume 30, Issue 18, , September 1996, Pages 3129-3140.


Abstract


The present work provides insights into the N- and S-pollution behaviour at rural and remote sites in Northern Europe. Formation of SO42- and NO3- from their precursor gases receives special attention in order to understand the significance of chemical conversion in shaping the distributions of concentration and deposition monitored at our sites : Säby-on the Swedish west coast, Lista-on the Norwegian south coast and South Uist-on the Hebride Islands in Northern Scotland. Owing mainly to the complexity of the problem, the approach is semiquantitative. Concentration patterns of S- and N-compounds for air mass transport between the sites were investigated for 10 periods (13d), within continental(6d) and oceanic (7 d) air masses. The observations spanned over both winter and summer days and conclusions could be drawn in some cases with respect to seasonality. The measurements were performed during the BMCAPE (Background Maritime Contribution to Atmospheric Pollution in Europe) project in 1993 and 1994. S- and N-ratios were used as indicators of air mass age, chemical conversion efficiency and en-route deposition. The S-ratio is defined as the ratio of particulate S (as SO42-) to total S (as SO2 and SO42-). The N-ratio is taken as the ratio of gaseous HNO3-N over particulate NO3--N. S-ratios at Säby and Lista agreed very well in those cases when no or insignificant precipitation occurred. Higher S-ratios and lower N-ratios were typical for conditions of high relative humidity. It is conceivable that condensed phase chemistry was of major importance in the SO2 oxidation and that HNO3 was absorbed onto the wet aerosol particles. Stagnation of the air masses over source regions of high emission densities and rates resulted in accumulation of pollution, the S-ratios in such conditions being high due to the longer transport time. The S-ratios for marine air flow at Säby and Lista no longer agreed (higher at Lista) as in the case of continental air masses. The reason is likely to be the proximity of the Lista station to the sea. Lista was highly affected by sea spray produced by the strong westerly winds. The N-ratio remained very low in the case of maritime air masses due to unexpectedly high NO3- concentrations. It is conceivable that the high load of NO3- is due to sea spray of surface water. More efficient SO2 deposition over land than over sea has been observed in the westerly airflow by the relative loss of SO2 while the flow swept over land.

 

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

Date added: 08/04/2011
Date modified: 08/04/2011
Filesize: 4.81 MB

M. Kulmala, A. Asmi, H.K. Lappalainen, U. Baltensperger, J.-L. Brenguier, , M. C. Facchini, H.-C. Hansson, Ø. Hov, C. O'Dowd, U. Poeschl, A. Wiedensohler,  R. Boers ,  O. Boucher,  G. De Leeuw, J. Feichter, R. Krejci ,  P. Laj, H. Lihavainen,  U. Lohmann, G. McFiggans, T. Mentel, C. Pilinis ,I.  Riipinen, M. Schultz, A. Stohl, E. Swietlicki, H. Denier Van den Gon , E. Vignati,  M. Amann,  C.Alves,  S. Arabas,  P. Artaxo, D.C.S. Beddows,  P. Beukes, R. Bergström,  M. Bilde, S. Clegg,  H. Coe,  B. d'Anna,  S. Gilardoni, J. Debernard, S.  Decesari,  M. Fischer,  A.M. Fjæraa, C. George, P. Halloran, T. Hamburger, R.M. Harrison, H. Herrman, T. Hoffmann,  C. Hoose, M Hu, U. Hõrrak, Y. Iinuma, T. Iversen,  M. Josipovic,  M. Junying, M. Kanakidou, A.Kiendler-Scharr,  A. Kirkevåg, G. Kiss,  Z. Klimont,    P. Kolmonen,  JE. Kristjansson, L. Laakso, A. Laaksonen, L. Labonnote, K.E.J. Lehtinen, R. Makkonen, G. McMeeking, J. Merikanto, A.Minikin, S.Mirme, W.T. Morgan, D. O’Donnell, TS. Panwar, H. Pawlowska, A Petzold, JJ. Pienaar, C. Pio,  C. Plass-Duelmer, A.S.H. Prévôt, S. Pryor, D. Rosenfeld, J. Schwarz, Ø. Seland, X.J. Shen, B. Sierau, D. Simpson,  J.Y.  Sun, D. Topping, P. Tunved, P. Vaattovaara, V. Vakkari, P. van Zyl, J.P. Veefkind,  B. Wehner, J. Wildt,  G. Visschedijk, S. Woodward, H. Vuollekoski, A. Zardini, K. Zhang, V.-M. Kerminen , K. Carslaw and S. N. Pandis. General Overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) - integrating aerosol research from nano to global scales, Atmos. Chem. & Phys. Disc., 11, 1–176, doi:10.5194/acpd-11-1-2011, 2011.

 


 

Abstract

In this paper we describe and summarize the main achievements of the European  Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI  started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy

including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) the first comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their ef10 fects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several  new aerosol parameterizations and computations modules for chemical transport and global climate models were  veloped and evaluated. This work enabled EUCAARI to improve our understanding of aerosol radiative forcing  15 and air quality-climate interactions. The EUCAARI results can be utilized in European  and global environmental policy to assess the erosol impacts and the corresponding  abatement strategies.

Global Average Concentration and Trend for Hydroxyl Radicals Deduced From ALE GAGE Trichloroeth Global Average Concentration and Trend for Hydroxyl Radicals Deduced From ALE GAGE Trichloroeth

Date added: 08/07/1992
Date modified: 07/24/2009
Filesize: 1.53 MB

Prinn, R., et al. (1992), Global Average Concentration and Trend for Hydroxyl Radicals Deduced From ALE/GAGE Trichloroethane (Methyl Chloroform) Data for 1978–1990, J. Geophys. Res., 97(D2), 2445–2461.


Abstract

Atmospheric measurements at several surface stations made between 1978 and 1990 of the anthropogenic chemical compound 1,1,1-trichloroethane (methyl chloroform, CH3CCl3) show it increasing at a global average rate of 4.4 ± 0.2% per year (1σ) over this time period. The measured trends combined with industrial emission estimates are used in an optimal estimation inversion scheme to deduce a globally averaged CH3CCl3 tropospheric (and total atmospheric) lifetime of 5.7 (+0.7, −0.6) years (1σ) and a weighted global average tropospheric hydroxyl radical (OH) concentration of (8.7 ± 1.0) × 105 radical cm−3 (1σ). Inclusion of a small loss rate to the ocean for CH3CCl3 of 1/85 year−1 does not affect the stated lifetime but lowers the stated OH concentration to (8.1 ± 0.9) × 105 radical cm−3 (1σ). The rate of change of the weighted global average OH concentration over this time period is determined to be 1.0 ± 0.8% per year (1σ) which has major implications for the oxidation capacity of the atmosphere and more specifically for methane (CH4), which like CH3CCl3 is destroyed primarily by OH radicals. Because the weighting strongly favors the tropical lower troposphere, this deduced positive OH trend is qualitatively consistent with hypothesized changes in tropical tropospheric OH and ozone concentrations driven by tropical urbanization, biomass burning, land use changes, and long-term warming. We caution, however, that our deduced rate of change in OH assumes that current industry estimates of anthropogenic emissions and our absolute calibration of CH3CCl3 are accurate. The CH3CCl3 measurements at our tropical South Pacific station (Samoa) show remarkable sensitivity to the E1 Nino-Southern Oscillation (ENSO), which we attribute to modulation of cross-equatorial transport during the northern hemisphere winter by the interannually varying upper tropospheric zonal winds in the equatorial Pacific. Thus measurements of this chemical compound have led to the discovery of a previously unappreciated aspect of tropical atmospheric tracer transport.

Global modelling of the oceanic source of organic aerosols, Global modelling of the oceanic source of organic aerosols,

Date added: 11/10/2010
Date modified: 11/10/2010
Filesize: 6.71 MB

Myriokefalitakis, S.,  E. Vignati, K. Tsigaridis, C. Papadimas, J. Sciare, N. Mihalopoulos, M. C. Facchini, M. Rinaldi, F. J. Dentener, D. Ceburnis, N. Hatzianastassiou, C.D. O'Dowd, M. van Weele and M. Kanakidou, Global modelling of the oceanic source of organic aerosols, Adv. in Meteorol., Volume 2010, Article ID 939171, doi:10.1155/2010/939171, 2010.

 


 

The global marine organic aerosol budget is investigated by a 3-dimensional chemistry-transport model considering recently proposed parameterisations of the primary marine organic aerosol (POA) and secondary organic aerosol (SOA) formation from the oxidation of marine volatile organic compounds. MODIS and SeaWiFS satellite data of Chlorophyll-a and ECMWF solar incoming radiation, wind speed, and temperature are driving the oceanic emissions in the model. Based on the adopted parameterisations, the SOA and the submicron POA marine sources are evaluated at about 5 Tg yr

 

1 (1.5 Tg C yr1) and 7 to 8 Tg yr1 (4 Tg C yr1), respectively. The computed marine SOA originates from the dimethylsulfide oxidation (78%), the potentially formed dialkyl amine salts (21%), and marine hydrocarbon oxidation (0.1%). Comparison of calculations with observations indicates an additional marine source of soluble organic carbon that could be partially encountered by marine POA chemical ageing.

Global scale emission and distribution of sea-spray aerosol: Global scale emission and distribution of sea-spray aerosol:

Date added: 03/03/2010
Date modified: 03/03/2010
Filesize: 1.37 MB

Vignati,, E.,  M. C. Facchini, M. Rinaldi, C. Scannell, D. Ceburnis, J. Sciare, M. Kanakidou, S. Myriokefalitakis, F. Dentener and C. D. O’Dowd , Global scale emission and distribution of sea spray aerosol: sea-salt and organic enrichment, Atmos. Envniron. 44,, doi:10.1016/j.atmosenv.2009.11.013  , 2010.


Abstract

The chemical composition of marine aerosols as a function of their size is an important parameter for theevaluation of their impact on the global climate system. In this work we modelled fine p

article organic matter emitted by sea spray processes and its influence on the aerosol chemical properties at the global scale using the off-line global Chemistry-Transport Model TM5. TM5 is coupled to a microphysical aerosol dynamics model providing size resolved information on particle masses and numbers. The mass of the emitted sea spray particles is partitioned between water insoluble organic matter (WIOM) and sea salt components in the accumulation mode using a function that relates the emitted organic fraction to the surface ocean chlorophyll-a concentrations. The global emission in the sub-micron size range of  organic matter by sea spray process is 8.2 Tg yr1, compared to 24 Tg fine yr1 sea-salt emissions. When  the marine sources are included, the concentrations of modelled primary particulate organic matter (POM) increase mainly over the oceans. The model predictions of WIOM and sea salt are evaluated  against measurements carried out at Mace Head (Northern Hemisphere) and Amsterdam Island  (Southern Hemisphere), showing that in clean marine conditions WIOM marine emissions contribute  significantly to POM values.  
fine particle organic matter emitted by sea spray processes and its influence on the aerosol chemical properties at the global scale using the off-line global Chemistry-Transport Model TM5. TM5 is coupled to a microphysical aerosol dynamics model providing size resolved information on particle masses and numbers. The mass of the emitted sea spray particles is partitioned between water insoluble organic matter (WIOM) and sea salt components in the accumulation mode using a function that relates the emitted organic fraction to the surface ocean chlorophyll-a concentrations. The global emission in the sub-micron size range of  organic matter by sea spray process is 8.2 Tg yr1, compared to 24 Tg fine yr1 sea-salt emissions. When  the marine sources are included, the concentrations of modelled primary particulate organic matter (POM) increase mainly over the oceans. The model predictions of WIOM and sea salt are evaluated  against measurements carried out at Mace Head (Northern Hemisphere) and Amsterdam Island  (Southern Hemisphere), showing that in clean marine conditions WIOM marine emissions contribute  significantly to POM values.
fine particle organic matter emitted by sea spray processes and its influence on the aerosol chemical properties at the global scale using the off-line global Chemistry-Transport Model TM5. TM5 is coupled to a microphysical aerosol dynamics model providing size resolved information on particle masses and numbers. The mass of the emitted sea spray particles is partitioned between water insoluble organic matter (WIOM) and sea salt components in the accumulation mode using a function that relates the emitted organic fraction to the surface ocean chlorophyll-a concentrations. The global emission in the sub-micron size range of  organic matter by sea spray process is 8.2 Tg yr1, compared to 24 Tg fine yr1 sea-salt emissions. When  the marine sources are included, the concentrations of modelled primary particulate organic matter (POM) increase mainly over the oceans. The model predictions of WIOM and sea salt are evaluated  against measurements carried out at Mace Head (Northern Hemisphere) and Amsterdam Island  (Southern Hemisphere), showing that in clean marine conditions WIOM marine emissions contribute  significantly to POM values.

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.

 

Global trends and emission estimates of CCl4 from in situ background observations from July 1978 to June 1996 Global trends and emission estimates of CCl4 from in situ background observations from July 1978 to June 1996

Date added: 08/01/1998
Date modified: 07/24/2009
Filesize: 1.15 MB

Simmonds, P. G., D. M. Cunnold, R. F. Weiss, R. G. Prinn, P. J. Fraser, A. McCulloch, F. N. Alyea, and S. O'Doherty (1998), Global trends and emission estimates of CCl4 from in situ background observations from July 1978 to June 1996, J. Geophys. Res., 103(D13), 16,017–16,027


Abstract


Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment/Advanced Global Atmospheric Gases Experiment (ALE/GAGE/AGAGE) measurements of CCl4 at five remote surface locations from 1978 to 1996 are reported. The Scripps Institution of Oceanography (SIO) 1993 absolute calibration scale is used, reducing the concentrations by a factor of 0.77 compared to previous ALE/GAGE reports. Atmospheric concentrations of CCl4 reached a peak in 1989-1990 of 104.4 ± 3.1 parts per trillion (ppt) and have since been decreasing 0.7 ± 0.1 ppt yr-1. Assuming an atmospheric lifetime of 42 ± 12 years, the emissions averaged 94-11+22 × 106 kg from 1979 to 1988 and 49-13+26 × 106 kg from 1991 to 1995. The reduction in the emissions in 1989-1990 coincided with a substantial decrease in the global production of the chlorofluorocarbons (CFCs). The total emission of CCl4 from countries that report annual production is estimated to have declined from 11% in 1972 to 4% in 1995 of the CCl4 needed to produce the CFC amounts reported. This implies that nonreporting countries released substantial amounts of CCl4 into the atmosphere in the 1980s and that their releases have exceeded those from the reporting countries since 1991.

Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene..... Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene.....

Date added: 08/05/2006
Date modified: 07/02/2009
Filesize: 1.92 MB
Simmonds, P. G., et al. (2006), Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene from the AGAGE observations at Mace Head, Ireland, and Cape Grim, Tasmania, J. Geophys. Res., 111, D18304, doi:10.1029/2006JD007082.

Abstract


In situ observations (every 4 hours) of dichloromethane (CH2Cl2) from April 1995 to December 2004 and trichloroethene (C2HCl3) and tetrachloroethene (C2Cl4) from September 2000 to December 2004 are reported for the Advanced Global Atmospheric Gases Experiment (AGAGE) station at Mace Head, Ireland. At a second AGAGE station at Cape Grim, Tasmania, CH2Cl2 and C2Cl4 data collection commenced in 1998 and 2000, respectively. C2HCl3 is below the limit of detection at Cape Grim except during pollution episodes. At Mace Head CH2Cl2 shows a downward trend from 1995 to 2004 of 0.7 ± 0.2 ppt yr−1 (ppt: expressed as dry mole fractions in 1012), although from 1998 to 2004 the decrease has been only 0.3 ± 0.1ppt yr−1. Conversely, there has been a small but significant growth of 0.05 ± 0.01 ppt yr−1 in CH2Cl2 at Cape Grim. The time series for C2HCl3 and C2Cl4 are relatively short for accurate trend analyses; however, we observe a small but significant decline in C2Cl4 (0.18 ± 0.05 ppt yr−1) at Mace Head. European emissions inferred from AGAGE measurements are compared to recent estimates from industry data and show general agreement for C2HCl3. Emissions estimated from observations are lower than industry emission estimates for C2Cl4 and much lower in the case of CH2Cl2. A study of wildfires in Tasmania, uncontaminated by urban emissions, suggests that the biomass burning source of CH2Cl2 may have been previously overestimated. All three solvents have distinct annual cycles, with the phases and amplitudes reflecting their different chemical reactivity with OH as the primary sink.

Globally significant oceanic source of organic carbon aerosol Globally significant oceanic source of organic carbon aerosol

Date added: 08/06/2008
Date modified: 07/24/2009
Filesize: 1.07 MB

Spracklen, D. V., S. R. Arnold, J. Sciare, K. S. Carslaw, and C. Pio (2008), Globally significant oceanic source of organic carbon aerosol, Geophys. Res. Lett., 35, L12811, doi:10.1029/2008GL033359.


Abstract


Significant concentrations of organic carbon (OC) aerosol are observed at three oceanic surface sites (Amsterdam Island, Azores and Mace Head). Two global chemical transport models (CTMs) underpredict OC concentrations at these sites (normalised mean bias of −67% and −58%). During periods of high biological activity monthly mean concentrations are underpredicted by a factor of 5–20. At Amsterdam Island and Mace Head, observed OC correlates well (R2 = 0.61–0.77) with back-trajectory weighted chlorophyll-a, suggesting an oceanic OC source driven by biological activity. We use a combination of remote sensed chlorophyll-a, back trajectories and observed OC to derive an empirical relation between chlorophyll-a and the total oceanic OC emission flux. Using the GEOS-chem CTM we show a global oceanic OC emission, from primary and secondary sources, of ∼8 Tg/year matches observations. This emission is comparable in magnitude to the fossil fuel OC source and increases the simulated global OC burden by 20%.

 

Ground-based and airborne observations of carbon monoxide during NASA Measurements of Air Pollu Ground-based and airborne observations of carbon monoxide during NASA Measurements of Air Pollu

Date added: 08/06/1998
Date modified: 07/24/2009
Filesize: 1.11 MB

B. G. Doddridge, R. Morales-Morales, K. P. Rhoads, J. T. Merrill, P. C. Novelli, R. R. Dickerson, V. S. Connors, and H. G. Reichle, Jr., “Ground-based and airborne observations of carbon monoxide during NASA Measurements of Air Pollution from Satellites (MAPS) missions SRL-1 and SRL-2,” J. Geophys. Res. 103, 19305–19316 (1998).


Abstract


Surface carbon monoxide (CO) data were acquired continuously at Heimaey, Iceland, (63tex2html_wrap_inline3724'N, 20tex2html_wrap_inline3718'W), Mace Head, Ireland, (53tex2html_wrap_inline3719'N, 9tex2html_wrap_inline3754'W), and Ragged Point, Barbados (13tex2html_wrap_inline3715'N, 59tex2html_wrap_inline3730'W) during April and October 1994, in support of MAPS missions SRL-1 and SRL-2, respectively, measuring middle tropospheric CO from space. Observed median CO levels from the three surface sites during these two MAPS missions approximate the monthly median for 1994, and are mostly typical of data from prior years. For two of the sites computed mission isentropic back-trajectory ensemble probability fields are compared to seasonal (March-May and September-November) probability fields for 1994 and 1986-1995. Such comparisons help gauge the representativeness of: (1) observed surface air quality at, and (2) isentropic flow to, these sites during the mission periods, in terms of intraseasonal and interannual variability. Results appear consistent with longer term flow climatological data and confirm the SRL-1 and SRL-2 mission periods are generally representative of the climatology applicable to these sites for the time of year. Lower free troposphere in situ CO data were acquired from an aircraft over the Maryland Eastern Shore on April 14 and October 3, 4 and 6. During the April flight a nearly linear gradient in CO with pressure from 1000-650 mb of 225-150 ppbv was observed. At 650 mb CO was quite steady around 150 ppbv; this value compares favorably with the MAPS CO data for the closest 5tex2html_wrap_inline37x5tex2html_wrap_inline37 grid box averaged April 13-15 of 105-120 ppbv. During SRL-2 a three flight CO average of 125 ppbv observed at  725 mb is in good agreement with the closest MAPS 5tex2html_wrap_inline37x5tex2html_wrap_inline37 grid box averaged October 3-7 of 90-105 ppbv. A layer of elevated CO at 845-740 mb, most likely the result of synoptic-scale transport, was observed during the October flights and seen to dissipate with time. The MAPS cloud filtered second-by-second CO data during concurrent Shuttle overflights show temporal structure consistent with the in situ observations, indicating the MAPS weighting function may be capable of discerning features at lower altitudes than thought previously.

 

Ground-based Retrieval of Continental and Marine Warm Cloud Microphysics Ground-based Retrieval of Continental and Marine Warm Cloud Microphysics

Date added: 08/05/2011
Date modified: 08/05/2011
Filesize: 3.85 MB

Martucci, G. and C.D. O’Dowd, Ground-based Retrieval of Continental and Marine Warm Cloud Microphysics. Atmos, Meas. Techs.. Diss., 4, 4825-4865, doi:10.5194/amtd-4-4825-2011,, 2011


Abstract. A technique for retrieving warm cloud microphysics using synergistic ground based remote sensing instruments is presented. The SYRSOC (SYnergistic Remote Sensing Of Cloud) technique utilises a Ka-band Doppler cloud RADAR, a LIDAR-ceilometer and a multichannel microwave radiometer. SYRSOC retrieves the main microphysical parameters such as cloud droplet number concentration (CDNC), droplets effective radius (reff), cloud liquid water content (LWC), and the departure from adiabatic conditions within the cloud. Two retrievals are presented for continental and marine stratocumulus formed over the Mace Head Atmospheric Research Station. Whilst the continental case exhibited high CDCN (N = 382 cm−3; 10th-to-90th percentile [9.4–842.4] cm−3) and small mean effective radius (reff = 4.3; 10th-to-90th percentile [2.9–6.5] μm), the marine case exhibited low CDNC and large mean effective radius (N = 25 cm−3, 10th-to-90th percentile [1.5–69] cm−3; reff = 25.6 μm, 10th-to-90th percentile [11.2–42.7] μm) as expected since the continental air at this location is typically more polluted than marine air. The large reff of the marine case was determined by the contribution of drizzle drops (large radii and few occurrences) and in fact the modal radius was reffMOD = 12 μm (smaller radius and large occurrences). The mean LWC was comparable for the two cases (continental: 0.19 g m−3; marine: 0.16 g m–3) but the 10th–90th percentile range was wider in marine air (continental: 0.11–0.22 g m−3; marine: 0.01–0.38 g m−3). The calculated algorithm uncertainty for the continental and marine case for each variable was, respectively, σN=141.34 cm−3 and 11.5 cm−3, σreff=0.8 μm and 3.2 μm, σLWC = 0.03 g m−3 and 0.03 g m−3. The retrieved CDNC are compared to the cloud condensation nuclei concentrations and the best agreement is achieved for a super-saturation of 0.1 % in the continental case and between 0.1 %–0.75 % for the marine stratocumulus. The retrieved reff at the top of the clouds are compared to the MODIS satellite reff: 7 μm (MODIS) vs 6.2 μm (SYRSOC) and 16.3 μm (MODIS) vs. 17 μm (SYRSOC) for continental and marine cases, respectively. The combined analysis of the CDNC and the reff, for the marine case shows that the drizzle modifies the droplet size distribution and reff especially if compared to reffMOD. The study of the cloud subadiabaticity and the LWC shows the general sub-adiabatic character of both clouds with more pronounced departure from adiabatic conditions in the continental case due to the shallower cloud depth and more significant mixing with dry tropospheric air.

Growth Rates During Coastal and Marine New Particle Formation in Western Ireland Growth Rates During Coastal and Marine New Particle Formation in Western Ireland

Date added: 11/10/2010
Date modified: 11/10/2010
Filesize: 1.75 MB

Ehn, M., H. Vuollekoski, T. Petäjä, V.-M. Kerminen, M. Vana, P. Aalto, G. de Leeuw, D. Ceburnis, R. Dupuy, C. D. O’Dowd and M. Kulmala, Growth Rates During Coastal and Marine New Particle Formation in Western Ireland, J. Geophys. Res., doi:10.1029/2010JD014292, 2010.


Growth rates of new particles during coastal and marine secondary aerosol particle

formation events were studied in western Ireland, both at the Mace Head atmospheric

research station and onboard the R/V 

Production project. Strong new particle formation events are frequently detected at Mace

Head caused by the emission of precursor gases from exposed seaweed during low tide.

Although these events were usually only detected as a mode of particles at a certain size, we

were able to link the size of the mode to the growth time of these particles after the initial

formation by combining data from several events measured between January 2006 and

November 2007 with an air ion spectrometer. Typically, the early growth rates were

extremely high, reaching values of several hundred nanometers per hour during the first

seconds. The growth rates rapidly decreased and reached values below 1 nm h 

1 h after nucleation. Our results were reproduced with box model calculations. All the

obtained growth rates could be explained by the model either by varying the precursor

formation time (typically a few seconds) or allowing multiple precursor vapor additions.

From the ship

ocean new particle formation detected in this region. In total, four events were detected

during this period, with three having a variable continental influence. An estimated

average growth rate in marine conditions was 3 nm h

Celtic Explorer as part of the Marine Aerosol 1 within borne measurements, we report the first observations of purely open 1 for these events.

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

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

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


Abstract


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

 

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.

Highlights of fifty years of atmospheric aerosol research at Mace Head Highlights of fifty years of atmospheric aerosol research at Mace Head

Date added: 09/23/2008
Date modified: 07/23/2009
Filesize: 2.08 MB

O’Connor, T.C., S.G. Jennings, and C.D. O’Dowd, Highlights from 50 years of Aerosol Measurements at Mace Head, Atmos. Res., 90, 338–355, doi:10.1016/j.atmosres.2008.08.014, 2008.


Abstract

 

This paper summarises the development and principal results of fifty years of research on aerosols in the marine atmosphere at Mace Head Atmospheric Research Station on the west coast of Ireland. It concentrates on the sources, physico-chemical properties, number and mass concentrations, size range, volatility and chemical composition of aerosols in different air masses. It also examines optical properties of the aerosols and their long-range transport.

Home Environment and Childhood Asthma Home Environment and Childhood Asthma

Date added: 07/31/1994
Date modified: 07/02/2009
Filesize: 224.33 kB

Leen, M.G., O'Connor, T.C., Kelleher, C.C., Loftus, B.G. & Mitchell, C. (1994)- Home environment and childhood asthma. The Irish Medical Journal, Vol. 87, No. 5, pp. 142-144.


Abstract


The prevalence of childhood asthma has increased dramatically in the past 20 years. The reasons for the increase are unclear but many authors suggest that changes in the home environment favourable to proliferation of the house dust mite are to blame. Our study aimed to compare home environment of children with asthma and controls. A questionnaire on home environment was administered to the parents of 134 children with asthma and 118 controls. Detailed studies of home temperature, humidity and dust mite allergen (DERpI) levels were performed in 20 homes (10 from each group). The questionnaire response rate was 86%. There were no significant differences between asthma and control homes with respect to social class, type of housing, smoking habits, pets, insulation, home heating, bedding, carpeting and domestic cleaning habits. A first degree family history of atopy wasobtained in 42% of asthmatic families and in 16% of controls. Temperature, humidity and dust mite allergen levels were similar in both groups. The majority gave readings exceeding recommended norms. Values for DERpI were above thresholds by a factor of 5 in 48%. Home environment does not significantly differ in children with or without asthma. The home environment is now generally mite friendly, and large segments of the childhood population are now exposed to high levels of DERpI. This may account for the increasing prevalence as more and more children with an atopic background develop overt symptoms in response to high levels of allergen load.

How falling raindrops collide How falling raindrops collide

Date added: 08/01/1972
Date modified: 07/02/2009
Filesize: 470.45 kB

S.G Jennings, P.R. Brazier-Smith, J. Latham, ,How falling raindrops collide,Page 313, New Scientist, 10 February 1972


Abstract

Hydroxyl Radical Concentrations Estimated from Measurements of Trichloroethylene during the EAS Hydroxyl Radical Concentrations Estimated from Measurements of Trichloroethylene during the EAS

Date added: 08/05/1999
Date modified: 07/24/2009
Filesize: 161.63 kB

Derwent, R.G., N. Carslaw, P. G. Simmonds, M. Bassford, S. O’Doherty, D.B. Ryall, M.J. Pilling, A.C. Lewis, and J.B. McQuaid, Hydroxyl radical concentrations estimated from measurements of trichloroethylene during the EASE/ACSOE campaign at Mace Head, Ireland during July 1996, J. Atmos Chem, 34, 185-205, 1999, (Ser. No. ACP107).


Abstract


During the EASE/OXICOA campaign of the NERC ACSOE programme, trichloroethylene and a wide range of man-made halocarbons and radiatively-active trace gases were monitored with high precision and high frequency throughout July 1996 at Mace Head on the Atlantic Ocean coast of Ireland. Trichloroethylene concentrations in concert with many other trace gases became elevated as regionally-polluted and photochemically-aged air masses reached Mace Head. However, as the anticyclonic air masses retreated during 19 and 20 July, trace gas concentrations remained elevated for a significant period. During this 2-4 day period, trichloroethylene concentrations decayed significantly, though the concentrations of the other more chemically-inert trace gases did not. A detailed interpretation of this behaviour using a Lagrangian dispersion model has allowed the estimation of average and peak OH radical concentrations of 3 and 9 × 106 molecule cm-3, respectively, during the travel from the source areas in the U.K. and the low countries out to Mace Head. Using a simple box model, the available Mace Head measurements, when combined into a detailed chemical mechanism, generated OH radical concentrations which peaked at 7 × 106 molecule cm-3, in close agreement with the estimates based on trichloroethylene decay.

 

Hygroscopic and CCN properties of aerosol particles in boreal forests Hygroscopic and CCN properties of aerosol particles in boreal forests

Date added: 07/31/2001
Date modified: 07/02/2009
Filesize: 498.17 kB
Hämeri, K. J.M. Mäkelä, L. Pirjola, M. Väkevä, P. Aalto, P. Miikkulainen, and C.D. O'Dowd, Hygroscopic properties of boreal forest aerosol during nucleation events. Tellus B, 53, 359-378, 2001

Abstract


The measurements of the hygroscopic and cloud condensation nuclei (CCN) properties of submicrometer atmospheric aerosol particles were performed with two tandem differential mobility analysers (TDMA) and a CCN counter at the Hyytia¨ la¨ forest field station in south-central Finland during the BIOFOR campaign. The TDMAs were used to measure hygroscopic diameter growth factors of individual aerosol particles in the dry particle diameter range 10–365 nm when taken from the dry state (relative humidity RH<5%) to RH=90%. The CCN counter was used to study the activation of aerosol particles when exposed to supersaturated conditions. The measurements show clear diurnal pattern of particle solubility. The pattern was strongest for particles in nucleation and Aitken modes. The lowest growth factor (soluble fraction) values were detected during late evening and early morning and the maximum was observed during noon–afternoon. The highest soluble fractions were determined for nucleation mode particles. The response of hygroscopic growth to changes of relative humidity suggests that the soluble compounds are either fully soluble or deliquescent well before 70% RH. The hygroscopic growth was investigated additionally by a detailed model using the size-resolved composition from the impactor samples. The comparison between different instruments shows good consistency. We found good agreement for the 20 nm growth factors measured with two TDMAs, not only on average but also regarding the temporal variation. The similar conclusion was drawn for comparison of TDMA with CCNC for Aitken mode particles with dry sizes 50 and 73 nm. Differences between wet and dry spectra measured using APS and CSASP spectrometer probes were used to derive growth factors for coarse mode particles. Growth factors for coarse mode particles (Dp ca. 2 mm) ranged between 1.0 and 1.6. Agreement between the evolution of growth factors with time for both accumulation and coarse modes was observed regularly. However, similar portions of the data set also indicated clear differences and consequently different chemical compositions between both modes. When the differences between both modes were observed, the coarse mode always behaved in a less hygroscopic manner, with growth factors near one.

Hygroscopic properties of nucleation mode and Aitken mode particles during nucleation bursts an Hygroscopic properties of nucleation mode and Aitken mode particles during nucleation bursts an

Date added: 08/06/2002
Date modified: 07/24/2009
Filesize: 925.58 kB

Väkevä, M., K. Hämeri, and P. P. Aalto (2002), Hygroscopic properties of nucleation mode and Aitken mode particles during nucleation bursts and in background air on the west coast of Ireland, J. Geophys. Res., 107(D19), 8104, doi:10.1029/2000JD000176.


Abstract


The hygroscopic and cloud condensation nuclei (CCN) properties of submicrometer atmospheric aerosol particles were investigated using an Ultrafine Tandem Differential Mobility Analyzer (UF-TDMA) and a CCN counter at the Mace Head Monitoring Station on the west coast of Ireland during the New Particle Formation and Fate in the Coastal Environment (PARFORCE) field campaign in September 1998 and June 1999. These measurements give indirect in situ information on the composition and state of mixing of the aerosol particles. The UF-TDMA was used for monitoring of hygroscopic diameter growth factors of aerosol particles with dry mobility diameters 8–20 nm when taken from dry state to a controlled humid environment (RH 90%). The CCN counter was used to study the activation of aerosol particles when exposed to supersaturated conditions (dry diameters of 15–150 nm). It was seen that in clean marine air masses during the observed particle formation events, the newly formed nucleation mode particles (8 and 10 nm) most often had low growth factors (between 1.0 and 1.1) resulting from low solubility. This indicates that the nucleation mode particles consist of nonsoluble or weakly soluble species, possible accompanied by a small soluble part; however, when nucleation mode particles were observed outside the event periods, the growth factors were higher (about 1.3–1.4). In contrast, the 20 nm particles usually clearly belonged to the Aitken mode (based on number size distribution measurements) and had hygroscopic properties similar to some common salts (growth factors 1.4–1.5).

 

Igac August 2001 Igac August 2001

Date added: 08/06/2001
Date modified: 08/06/2008
Filesize: 1.91 MB

Impact of halogen monoxide chemistry upon boundary layer OH and HO 2 concentrations at a coasta Impact of halogen monoxide chemistry upon boundary layer OH and HO 2 concentrations at a coasta

Date added: 08/06/2005
Date modified: 07/24/2009
Filesize: 187.73 kB

Bloss, W. J.; Lee, J. D.; Johnson, G. P.; Sommariva, R.; Heard, D. E.; Saiz-Lopez, A.; Plane, J. M. C.; McFiggans, G.; Coe, H.; Flynn, M.; Williams, P.; Rickard, A. R.; Fleming, Z. L. Impact of halogen monoxide chemistry upon boundary layer OH and HO2 concentrations at a coastal site Geophys. Res. Lett., Vol. 32, No. 6, L06814 10.1029/2004GL022084


Abstract


The impact of iodine oxide chemistry upon OH and HO2 concentrations in the coastal marine boundary layer has been evaluated using data from the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, conducted at Mace Head, Ireland during the summer of 2002. Observationally constrained calculations show that under low NOx conditions experienced during NAMBLEX (NO ≤ 50 pptv), the reaction IO + HO2 → HOI + O2 accounted for up to 40% of the total HO2 radical sink, and the subsequent photolysis of HOI to form OH + I comprised up to 15% of the total midday OH production rate. The XO + HO2 (X = Br, I) reactions may in part account for model overestimates of measured HO2 concentrations in previous studies at Mace Head, and should be considered in model studies of HOx chemistry at similar coastal locations.

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.

 

Importance of organic and black carbon in atmospheric aerosols at Mace Head, on the West Coast of Ireland (53°19′N, 9°54′W) Importance of organic and black carbon in atmospheric aerosols at Mace Head, on the West Coast of Ireland (53°19′N, 9°54′W)

Date added: 07/31/2002
Date modified: 07/24/2009
Filesize: 146.78 kB

Kleefeld, S., Hoffer, A., Krivacsy, and Jennings, S.G., 2002. Importance of organic and black carbon at Mace Head, on the west coast of Ireland (53 019’N, 9 054’W), Atmos. Environ., 36, pp. 4479-4490.


Abstract


The mass concentrations of total organic carbon (TC) and its chemical fractions, water-soluble organic carbon (WSOC), water-insoluble organic carbon (WISOC), and black carbon (BC), were determined in marine aerosols, which were collected during the period July 1998-September 1999 at the Mace Head Atmospheric Research Station on the west coast of Ireland. In addition, mass concentrations of major inorganic ions, like non-sea-salt (NSS) sulphate, and mass concentrations of dicarboxylic acids have been measured separately within the water-soluble aerosol fraction. The aerosol samples were classified into clean marine aerosol samples and modified marine aerosol samples according to the origin of air masses arriving at Mace Head, and using BC as a tracer for anthropogenic pollution. Following this classification, the data set was further divided into samples taken during summertime and wintertime. An average TC mass concentration of 591±75 ng/m3 was determined for all aerosol samples taken at Mace Head. WSOC was found to be the dominating fraction in modified marine aerosol samples, followed by WISOC and BC, whereas in clean marine aerosol samples WISOC was the main fraction, followed by WSOC, and BC. A comparison of the mass concentration of the water-soluble organic matter to the main water-soluble inorganic component, NSS sulphate, gave an average ratio of 0.72±0.10, which increased to 1.59±0.23 when considering solely clean marine aerosol samples. The dominating dicarboxylic acid found in carbonaceous aerosols at Mace Head was oxalic acid, followed by malonic acid. Both diacids were responsible for about 14±2% of the WSOC (in terms of carbon).

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.

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.

In situ measurements of atmospheric methane at GAGE AGAGE sites during 1985–2000 and resulting source inferences In situ measurements of atmospheric methane at GAGE AGAGE sites during 1985–2000 and resulting source inferences

Date added: 08/01/2002
Date modified: 07/24/2009
Filesize: 7.81 MB
Cunnold, D. M., et al. (2002), In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985–2000 and resulting source inferences, J. Geophys. Res., 107(D14), 4225, doi:10.1029/2001JD001226.

Abstract


Continuous measurements of methane since 1986 at the Global Atmospherics Gases Experiment/Advanced Global Atmospherics Gases Experiment (GAGE/AGAGE) surface sites are described. The precisions range from approximately 10 ppb at Mace Head, Ireland, during GAGE to better than 2 ppb at Cape Grim, Tasmania, during AGAGE (i.e., since 1993). The measurements exhibit good agreement with coincident measurements of air samples from the same locations analyzed by Climate Monitoring and Diagnostics Laboratory (CMDL) except for differences of approximately 5 ppb before 1989 (GAGE lower) and about 4 ppb from 1991 to 1995 (GAGE higher). These results are obtained before applying a factor of 1.0119 to the GAGE/AGAGE values to place them on the Tohoku University scale. The measurements combined with a 12-box atmospheric model and an assumed atmospheric lifetime of 9.1 years indicates net annual emissions (emissions minus soil sinks) of 545 Tg CH4 with a variability of only ±20 Tg from 1985 to 1997 but an increase in the emissions in 1998 of 37 ± 10 Tg. The effect of OH changes inferred by Prinn et al. [2001] is to increase the estimated methane emissions by approximately 20 Tg in the mid-1980s and to reduce them by 20 Tg in 1997 and by more thereafter. Using a two-dimensional (2-D), 12-box model with transport constrained by the GAGE/AGAGE chlorofluorocarbon measurements, we calculate that the proportion of the emissions coming from the Northern Hemisphere is between 73 and 81%, depending on the OH distribution used. However, this result includes an adjustment of 5% derived from a simulation of the 2-D estimation procedure using the 3-D MOZART model. This adjustment is needed because of the very different spatial emission distributions of the chlorofluorocarbons and methane which makes chlorofluorocarbons derived transport rates inaccurate for the 2-D simulation of methane. The 2-D model combined with the annual cycle in OH from Spivakovsky et al. [2000] provide an acceptable fit to the observed 12-month cycles in methane. The trend in the amplitude of the annual cycle of methane at Cape Grim is used to infer a trend in OH in 30°–90°S of 0 ± 5% per decade from 1985 to 2000, in qualitative agreement with Prinn et al. [2001] for the Southern Hemisphere.

In situ, gas chromatographic measurements of non-methane hydrocarbons and dimethyl sulfide at a In situ, gas chromatographic measurements of non-methane hydrocarbons and dimethyl sulfide at a

Date added: 08/05/1997
Date modified: 07/24/2009
Filesize: 587.14 kB

Lewis, A.C.; Bartle, K.D.; Heard, D.E.; McQuaid, J.B.; Pilling, M.J.; Seakins, P.W. (1997) In situ, gas chromatographic measurements of non-methane hydrocarbons and dimethyl sulfide at a remote coastal location (Mace Head, Eire) July-August 1996, Faraday Transactions, 93,  pp.2921-2927.


Abstract


Atmospheric non-methane hydrocarbons (NMHC) and dimethyl sulÐde (DMS) have been monitored at a remote coastal location Mace Head, Eire) using adsorption sampling techniques with analysis by in situ gas chromatography as part of the ACSOE OXICOA 1996 campaign. Concentrations varied considerably during the campaign but can be consistently interpreted by consideration of the relevant back-trajectory of the monitored air mass. Isoprene is conÐrmed as the most important NMHC in determining OH removal, contributing to up to 20%. Isoprene shows strong diurnal variations, although the structure of the diurnal pattern depends on the origin of the air mass. In contrast to previous studies, DMS concentrations during the campaign appeared to show no consistent diurnal variation.

Increased rates of rainfall production in Electrified clouds Increased rates of rainfall production in Electrified clouds

Date added: 07/30/1973
Date modified: 07/22/2009
Filesize: 822.23 kB

Brazier-Smith, P.R., Jennings, S.G., and Latham, J. (1973)- Increasing rates of rainfall production in electrified clouds. Quart. J. Roy. Met. Soc., 99, 776-779


Abstract

Influence of an increased sea surface temperature on North Atlantic cyclones Influence of an increased sea surface temperature on North Atlantic cyclones

Date added: 09/23/2008
Date modified: 07/23/2009
Filesize: 2.79 MB

Semmler, S. Varghese, R. McGrath, P. Nolan, S. Wang, P. Lynch, C. O'Dowd, Influence of an increased sea surface temperature on North Atlantic cyclones, J. Geophys. Res, D02107, doi/2006JD008213, 2008.


Abstract

 

The influence of an increased sea surface temperature (SST) on the frequency and intensity of cyclones over the North Atlantic is investigated using two 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 reanalysis data for May to December 1985–2000 at the lateral and lower boundaries, using SST and lateral boundary temperatures. A realistic interannual variation in tropical storm and hurricane counts is simulated. In an idealized sensitivity experiment, SSTs and boundary condition temperatures at all levels are increased by 1 K to ensure that we can distinguish the SST from other factors influencing the development of cyclones. An increase in the count of strong hurricanes is simulated. There is not much change in the location of hurricanes. Generally weaker changes are seen in the extratropical region
and for the less extreme events. Increases of 9% in the count of extratropical cyclones and 39% in the count of tropical cyclones with wind speeds of at least 18 m/s are found.

Interannual and seasonal variability in atmospheric N 2 O Interannual and seasonal variability in atmospheric N 2 O

Date added: 08/06/2007
Date modified: 07/24/2009
Filesize: 673.42 kB

Nevison, C. D., N. M. Mahowald, R. F. Weiss, and R. G. Prinn (2007), Interannual and seasonal variability in atmospheric N2O, Global Biogeochem. Cycles, 21, GB3017, doi:10.1029/2006GB002755.


Abstract


The increase in atmospheric N2O observed over the last century reflects large-scale human perturbations to the global nitrogen cycle. High-precision measurements of atmospheric N2O over the last decade reveal subtle signals of interannual variability (IAV) superimposed upon the more prominent growth trend. Anthropogenic sources drive the underlying growth in N2O, but are probably too monotonic to explain most of the observed IAV. The causes of both seasonal and interannual variability in atmospheric N2O are explored on the basis of comparisons of a 1993–2004 atmospheric transport simulation to observations of N2O at five stations of the Advanced Global Atmospheric Gases Experiment (AGAGE). The complementary tracers chlorofluorocarbons (CFCs) 11 and 12 and SF6 also are examined. The model simulation does not include a stratospheric sink and thus isolates the effects of surface sources and tropospheric transport. Both model and observations yield correlations in seasonal and interannual variability among species, but only in a few cases are model and observed variability correlated to each other. The results suggest that tropospheric transport contributes substantially to observed variability, especially at Samoa station. However, some features of observed variability are not explained by the model simulation and appear more consistent with a stratospheric influence. At Mace Head, Ireland, N2O and CFC growth rate anomalies are weakly correlated to IAV in polar winter lower stratospheric temperature, a proxy for the strength of the mean meridional stratospheric circulation. Seasonal and interannual variability in the natural sources of N2O may also contribute to observed variability in atmospheric N2O.

 

Interannual and seasonal variability in atmospheric N 2 O Interannual and seasonal variability in atmospheric N 2 O

Date added: 08/06/2007
Date modified: 07/02/2009
Filesize: 673.42 kB

Nevison, C. D., N. M. Mahowald, R. F. Weiss, and R. G. Prinn (2007), Interannual and seasonal variability in atmospheric N2O, Global Biogeochem. Cycles, 21, GB3017, doi:10.1029/2006GB002755.


Abstract


The increase in atmospheric N2O observed over the last century reflects large-scale human perturbations to the global nitrogen cycle. High-precision measurements of atmospheric N2O over the last decade reveal subtle signals of interannual variability (IAV) superimposed upon the more prominent growth trend. Anthropogenic sources drive the underlying growth in N2O, but are probably too monotonic to explain most of the observed IAV. The causes of both seasonal and interannual variability in atmospheric N2O are explored on the basis of comparisons of a 1993–2004 atmospheric transport simulation to observations of N2O at five stations of the Advanced Global Atmospheric Gases Experiment (AGAGE). The complementary tracers chlorofluorocarbons (CFCs) 11 and 12 and SF6 also are examined. The model simulation does not include a stratospheric sink and thus isolates the effects of surface sources and tropospheric transport. Both model and observations yield correlations in seasonal and interannual variability among species, but only in a few cases are model and observed variability correlated to each other. The results suggest that tropospheric transport contributes substantially to observed variability, especially at Samoa station. However, some features of observed variability are not explained by the model simulation and appear more consistent with a stratospheric influence. At Mace Head, Ireland, N2O and CFC growth rate anomalies are weakly correlated to IAV in polar winter lower stratospheric temperature, a proxy for the strength of the mean meridional stratospheric circulation. Seasonal and interannual variability in the natural sources of N2O may also contribute to observed variability in atmospheric N2O.

 

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).

 

Intercomparison of elemental concentrations in total and size-fractionated aerosol samples coll Intercomparison of elemental concentrations in total and size-fractionated aerosol samples coll

Date added: 08/07/1995
Date modified: 07/24/2009
Filesize: 1.12 MB

Francois F., Maenhaut W., Colin J.L., Losno R., Schulz M., Stahlschmidt T., Spokes L.,
Jickells T., Intercomparison of Elemental Concentrations in Total and Size-Fractionated
Aerosol Samples Collected During the Mace Head Experiment, April 1991, Atmos. Environ.
29, 1995, 837-849.


Abstract


During an intercomparison field experiment, organized at the Atlantic coast station of Mace Head, Ireland, in April 1991, aerosol samples were collected by four research groups. A variety of samplers was used, combining both high- and low-volume devices, with different types of collection substrates: Hi-Vol Whatman 41 filter holders, single Nuclepore filters and stacked filter units, as well as PIXE cascade impactors. The samples were analyzed by each participating group, using in-house analytical techniques and procedures. The intercomparison of the daily concentrations for 15 elements, measured by two or more participants, revealed a good agreement for the low-volume samplers for the majority of the elements, but also indicated some specific analytical problems, owing to the very low concentrations of the non-sea-salt elements at the sampling site. With the Hi-Vol Whatman 41 filter sampler, on the other hand, much higher results were obtained in particular for the sea-salt and crustal elements. The discrepancy was dependent upon the wind speed and was attributed to a higher collection efficiency of the Hi-Vol sampler for the very coarse particles, as compared to the low-volume devices under high wind speed conditions. The elemental mass size distribution, as derived from parallel cascade impactor samplings by two groups, showed discrepancies in the submicrometer aerosol fraction, which were tentatively attributed to differences in stage cut-off diameters and/or to bounce-off or splintering effects on the quartz impactor slides used by one of the groups. However, the atmospheric concentrations (sums over all stages) were rather similar in the parallel impactor samples and were only slightly lower than those derived from stacked filter unit samples taken in parallel.

 

Intercomparison Of Formaldehyde Intercomparison Of Formaldehyde

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

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

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


Abstract

 

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

Intercomparison of formaldehyde measurements in clean and polluted atmospheres Intercomparison of formaldehyde measurements in clean and polluted atmospheres

Date added: 08/06/2000
Date modified: 07/24/2009
Filesize: 222.47 kB

Cardenas, L.M., Brassington, D.J., Allan, B.J., Coe, H., Alicke, B., Platt, U., Wilson, K.M., Plane, J.M.C. and Penkett, S.A., 2000. Intercomparison of formaldehyde measurements in clean and polluted atmospheres. Journal of Atmospheric Chemistry 37, pp. 53–80.


Abstract


Three different techniques used tomeasure atmospheric formaldehyde were compared duringa field campaign carried out at a clean maritime siteon the West coast of Ireland. Two spectroscopictechniques Differential Optical AbsorptionSpectroscopy (DOAS) and Tunable Diode Laser AbsorptionSpectroscopy (TDLAS), together with a glass coil/Hantzschreaction/fluorescence technique, wereemployed for measurements of atmospheric formaldehydeof the order of a few hundred pptv. The betteragreement was observed between the fluorescence andDOAS instruments.Two DOAS instruments were compared to the glasscoil/Hantzsch reaction/fluorescence technique at asemi-polluted site on the North Norfolk coast, U.K.,where concentrations of formaldehyde were observed atlevels up to 4 ppbv. A very good agreement wasobserved between the two instruments.The glass coil/Hantzsch reaction/fluorescence and theTDLAS instruments were also deployed simultaneously inorder to measure indoor air inside a mobile laboratorylocated at the Imperial College Silwood Park site nearAscot, U.K. The doors of the mobile laboratory wereleft open in order to obtain the backgroundformaldehyde concentrations. Closing them afterwardsallowed us to observe the increase in concentrationsas a result of indoor emissions. The agreement betweenthe two instruments was outstanding (correlationcoefficient was 99%).The results from this study showed that of the fourinstruments included in this intercomparison the glasscoil/Hantzsch reaction/fluorescence technique provedthe most suitable for continuous measurements offormaldehyde in the background atmosphere.

Intercomparison of measurement methods for black carbon aerosols Intercomparison of measurement methods for black carbon aerosols

Date added: 08/01/1999
Date modified: 07/02/2009
Filesize: 201.1 kB

Hitzenberger, R., Jennings, S.G., Larson, S.M., Dillner, A., Cachier, H., Galambos, Z., Rouc, A. and Spain, T.G. (1999). Intercomparison of measurement methods for black carbon aerosols. Atmos. Environ., 33, 2823-2833.


Abstract


In this study, two method intercomparisons were performed. One thermal and two optical methods for the measurement of black carbon (BC) were applied to laboratory generated aerosols containing only BC. For the optical measurements, an aethalometer (Hansen et al., 1984. Science of Total Environment 36, 191-196) and an integrating sphere technique (Hitzenberger et al., 1996b. Journal of Geophysical Research 101, D14, 19&unknown;601-19&unknown;606) were used. The thermal method was described by Cachier et al. (1989a. Tellus 41B, 379-390). In an additional comparison, the integrating sphere was compared to a thermal optical technique (Birch and Cary, 1996. Aerosol Science Technology 25, 221-241) on ambient aerosol samples. The absorption coefficients were obtained from transmission measurements on filter samples for both the aethalometer and the integrating sphere. The BC mass concentration for the aethalometer was derived from this absorption measurement. The BC mass concentration for the integrating sphere, however, was obtained using an independent calibration curve. The agreement between the absorption coefficient sigmaa obtained for the BC test aerosol on parallel filters with the aethalometer and the integrating sphere was satisfactory. The slope of the regression lines depended on filter type. A comparison between BC mass concentrations, however, showed that the aethalometer values were only 23% of those obtained by the integrating sphere technique indicating that for pure BC aerosols, the standard aethalometer calibration should not be used. Compared to the thermal method, the integrating sphere gave an overestimation of the BC mass concentrations by 21%. For the ambient samples, the integrating sphere and the thermal optical methods for BC mass concentration determination showed agreement within 5% of the 1:1 line, although the data were not so well correlated.

Intercomparison of number concentration measurements by various aerosol particle counters Intercomparison of number concentration measurements by various aerosol particle counters

Date added: 07/31/2002
Date modified: 07/02/2009
Filesize: 535.01 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, A. Mirme, 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, Intercomparison of number concentration measurements by various aerosol particle counters. Atmos. Res. 62, 177-208, 2002.


Abstract

 

Total aerosol particle number concentrations, as measured by means of 16 different measurement systems, have been quantitatively compared 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 (ICCP-IUGG). The range of measuring instruments includes Pollak counters (PCO) in use already for several decades, presently available commercial particle counters, as well as laboratory prototypes. The operation of the instruments considered was based on different measurement principles: (1) adiabatic expansion condensation particle counter, (2) flow diffusion condensation particle counter, (3) turbulent mixing condensation particle counter, (4) laser optical particle counter, and (5) electrostatic particle measurement system. Well-defined test aerosols with various chemical compositions were considered: DEHS, sodium chloride, silver, hydrocarbons, and tungsten oxide. The test aerosols were nearly monodispersed with mean particle diameters between 4 and 520 nm, the particle number concentrations were varied over a range from about 4 × 101 to 7 × 106 cm-3. A few measurements were performed with two-component aerosol mixtures. For simultaneous concentration measurements, the various instruments considered were operated under steady state conditions in a linear flow system. A series of at least 10 single concentration measurements was performed by each individual instrument at each set of test aerosol parameters. The average of the concentration data measured by the various instruments was defined as a common reference. The number concentrations obtained from the various instruments typically agreed within a factor of about two over the entire concentration range considered. The agreement of the measured concentrations is notable considering the various different measurement principles applied in this study, and particularly in view of the broad range of measurement instruments used. Significant deviations and nonlinear response were observed only in a few cases and are possibly related to calibration errors. For certain conditions, a dependence of aerosol counter response on particle composition has been found. The scatter of the number concentrations obtained from each individual instrument during measurements with constant test aerosol typically did not exceed 20% to 25%. At concentrations below 103 cm-3, however, several of the instruments, including electrostatic particle measurement systems, tend to show increased experimental scatter.

International field intercomparison measurements of atmospheric mercury species at Mace Head, Ireland International field intercomparison measurements of atmospheric mercury species at Mace Head, Ireland

Date added: 07/31/1999
Date modified: 07/24/2009
Filesize: 195.51 kB

Ebinghaus, R., Jennings, S.G., Schroeder, W.H., Berg, T., Donaghy., Guentzel, J., Kenny, C., Kock, H.H., Kvietkus, K., Landing, W., Munthe, J., Prestbo, E.M., Schneeberger, D., Slemr, F., Sommar, J., Urba, A., Wallschlager, D. & Xiao, Z. 1999. International field intercomparison measurements of atmospheric mercury species at Mace Head, Ireland. Atmos. Environ., 33, 3063-3073.


Abstract


Eleven laboratories from North America and Europe met at Mace Head, Ireland for the period 11-15 September 1995 for the first international field intercomparison of measurement techniques for atmospheric mercury species in ambient air and precipitation at a marine background location. Different manual methods for the sampling and analysis of total gaseous mercury (TGM) on gold and silver traps were compared with each other and with new automated analyzers. Additionally, particulate-phase mercury (Hgpart) in ambient air, total mercury, reactive mercury and methylmercury in precipitation were analyzed by some of the participating laboratories. Whereas measured concentrations of TGM and of total mercury in precipitation show good agreement between the participating laboratories, results for airborne particulate-phase mercury show much higher differences. Two laboratories measured inorganic oxidized gaseous mercury species (IOGM), and obtained levels in the low picogram m-3 range.

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

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

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


Abstract


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

Investigating organic aerosol loading in the remote marine environment Investigating organic aerosol loading in the remote marine environment

Date added: 09/01/2011
Date modified: 11/17/2011
Filesize: 2.42 MB

Lapina, K., C.L. Heald, D.V. Spracklen, S.R. Arnold, J.D. Allan, H Coe, G. McFiggans, S.R. Zorn, F. Drewnick, T.S. Bates, L.N. Hawkins, L.M. Russell, A. Smirnov, C. O'Dowd and A.J. Hind. Investigating organic aerosol loading in the remote marine environment, Atmos. Chem. Phys., 11, 8847–8860, 2011, doi:10.5194/acp-11-8847-2011.

 

  

Abstract: Aerosol loading in the marine environment is investigated using aerosol composition

measurements from several research ship campaigns (ICEALOT, MAP, RHaMBLe, VOCALS

and OOMPH), observations of total AOD column from satellite (MODIS) and ship-based instruments (Maritime Aerosol Network, MAN), and a global chemical transport model (GEOS-Chem). This work represents the most comprehensive evaluation of oceanic OM emission inventories to date, by employing aerosol composition measurements obtained from campaigns with wide spatial and temporal coverage. The model

underestimates AOD over the remote oceans on average by 0.02 (21 %), compared to satellite observations, but provides an unbiased simulation of ground-based Maritime Aerosol Network (MAN) observations. Comparison with cruise data demonstrates that the GEOS-Chem simulation of marine sulfate, with the mean observed values ranging between 0.22 μgm−3 and 1.34 μgm−3, is generally unbiased, however surface organic matter (OM) concentrations, with the mean observed concentrations between 0.07 μgm−3 and 0.77 μgm−3, are underestimated by a factor of 2-5 for the standard model run. Addition of a a sub-micron marine OM source of approximately 9 TgCyr−1 brings the model into agreement with the ship-based measurements, however this additional OM source does not explain the model underestimate of marine AOD. The model underestimate of marine AOD is therefore likely the result of a combination of satellite retrieval bias and a missing marine aerosol source (which exhibits a different spatial pattern than existing aerosol in the model).

  


Iodine dioxide nucleation simulations in coastal and remote marine environments Iodine dioxide nucleation simulations in coastal and remote marine environments

Date added: 04/08/2009
Date modified: 07/28/2009
Filesize: 685.8 kB
Vuollekoski, H., V.-M. Kerminen, T. Anttila, S.-L. Sihto, M. Vana, M. Ehn, H. Korhonen, G. McFiggans, C. D. O’Dowd and M. Kulmala,,  Iodine dioxide nucleation simulations in coastal and remote marine environments, J. Geophys. Res., 114, D02206, doi:10.1029/2008JD010713, 2008

Abstract

 

Aerosol dynamical box model simulations of coastal new particle formation were performed in order to investigate the nucleation and growth mechanisms in this environment. In the simulations the nucleating vapor was assumed to be iodine dioxide (OIO). Both Eulerian and Lagrangian type simulations were made and compared with observations. We tested three nucleation mechanisms: kinetic nucleation of OIO (K  [OIO]2), activation of clusters by OIO (A  [OIO]) and sulphuric acid-induced activation of clusters containing OIO (B  [OIO]  [H2SO4]). All the nucleation mechanisms provided reasonable results, although the growth of particles due to condensation is inadequate in kinetic nucleation cases as compared with experimental measurements. Growth of newly formed particles could be assisted by any low-volatility vapors should their concentration exceed 109 cm3. Using the obtained values of coefficients K, A, and B we found that nucleation driven by iodine compounds in remote marine areas is possible, but by OIO and H2SO4 alone, only a minor fraction of newly formed particles is likely to reach detectable sizes. Owing to the scavenging by coagulation with background aerosol particles, few of them will likely reach climatically relevant sizes by acting as seed particles for other low-volatility vapors. In order to elucidate the significance of our results, more detailed measurements of OIO source and photolysis rates, dimensions of precursor areas, and particle chemical composition are needed.

Iodine Oxide Homogeneous Nucleation An Explanation for Coastal New Particle Production Iodine Oxide Homogeneous Nucleation An Explanation for Coastal New Particle Production

Date added: 07/31/2001
Date modified: 07/24/2009
Filesize: 423.83 kB

Hoffmann, T, CD O'Dowd, JH Seinfeld, Iodine oxides and new particle formation, Geophys. Res. Letts., 27, 1949-1952, 2001.


Abstract


A series of laboratory experiments on the chemical composition of aerosol particles formed after photodissociation of CH2I2, a major volatile alkyl halide released from macroalgae, have been performed in a laboratory scale reaction chamber using on-line atmospheric pressure chemical ionization mass spectrometry (APCI/MS). Based on the mass spectrometric results and the molecular properties of iodine oxides, we suggest that the self-nucleation of iodine oxides provides an efficient source of natural condensable material in coastal environments and discuss this concept focusing on OIO as one potential key species for new particle formation. The presented hypothesis not only fits the measured enrichment of iodine species in submicrometer particles, but also can explain the frequently observed nucleation bursts in the coastal boundary layer.

Ionization Equibrium of maritime Air Ionization Equibrium of maritime Air

Date added: 08/07/1960
Date modified: 07/24/2009
Filesize: 5.83 MB
O'Connor, T.C, Sharkey, W.P, Ionization Equilibrium In Maritime Air, Procedding of the Royal irish Academy, Volume 61, Section A, No. 3
Abstract
«StartPrev12345678910NextEnd»
Page 5 of 11
Copyright © 2017 Atmospheric Physics Research Cluster. All Rights Reserved.
Joomla! is Free Software released under the GNU/GPL License.
 
None