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Journal Publications

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

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Documents

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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.

 

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%.

 

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.

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 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 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 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 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.

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.

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.

 

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.

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.

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

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.

 

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.

Flood or Drought: How Do Aerosols Affect Precipitation? Flood or Drought: How Do Aerosols Affect Precipitation?

Date added: 09/12/2008
Date modified: 07/01/2009
Filesize: 1.93 MB

Flood or Drought: How Do Aerosols Affect Precipitation? Daniel Rosenfeld, Ulrike Lohmann, Graciela B. Raga, Colin D. O'Dowd, Markku Kulmala, Sandro Fuzzi, Anni Reissell, and Meinrat O. Andreae (5 September 2008) Science 321 (5894), 1309. [DOI: 10.1126/science.1160606]


Abstract


Aerosols serve as cloud condensation nuclei (CCN) and thus have a substantial effect on cloud properties and the initiation of precipitation. Large concentrations of human-made aerosols have been reported to both decrease and increase rainfall as a result of their radiative and CCN activities. At one extreme, pristine tropical clouds with low CCN concentrations rain out too quickly to mature into long-lived clouds. On the other hand, heavily polluted clouds evaporate much of their water before precipitation can occur, if they can form at all given the reduced surface heating resulting from the aerosol haze layer. We propose a conceptual model that explains this apparent dichotomy.

First experimental evidence of new particle formation from organic vapours over forests First experimental evidence of new particle formation from organic vapours over forests

Date added: 07/31/2002
Date modified: 07/01/2009
Filesize: 97.37 kB

O'Dowd, C.D. K. Hämeri, P. Aalto, and M. Kulmala, First experimental evidence of new particle formation from organic vapours over forests, Nature, 416, 497-498, 2002.


Abstract


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

First appearance and rapid growth of anthropogenic HFC-245fa (CHF2CH2CF3) in the atmosphere First appearance and rapid growth of anthropogenic HFC-245fa (CHF2CH2CF3) in the atmosphere

Date added: 08/05/2006
Date modified: 07/01/2009
Filesize: 398.7 kB
Vollmer, M. K., S. Reimann, D. Folini, L. W. Porter, and L. P. Steele (2006), First appearance and rapid growth of anthropogenic HFC-245fa (CHF2CH2CF3) in the atmosphere, Geophys. Res. Lett., 33, L20806, doi:10.1029/2006GL026763.

Abstract


We capture the first atmospheric appearance of HFC-245fa (CHF2CH2CF3), a new foam blowing agent. Our results from the high-altitude observatory at Jungfraujoch, Switzerland, show a rapid growth of this substance in the northern hemispheric troposphere from 0.28 ppt in July 2004 to 0.68 ppt at the end of 2005, which corresponds to an overall increase of >90% per year. By combining our observations with an atmospheric 3-box model we estimate a southern hemispheric trend for this trace gas which we compare to observations at southern hemisphere mid-latitudes. We also estimate a global HFC-245fa emissions increase from 2100–2400 tonnes in 2003 to 5100–5900 tonnes in 2005. Pollution episodes are relatively rare at Jungfraujoch compared to other hydrofluorocarbons thereby confirming the limited use of HFC-245fa in Europe. Back trajectory analysis reveals the largest potential European sources of HFC-245fa in northern Italy and northeastern Spain.

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

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

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


Abstract


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

 

Extinction and liquid water content of fog at visible wavelengths Extinction and liquid water content of fog at visible wavelengths

Date added: 07/31/1983
Date modified: 07/01/2009
Filesize: 2.27 MB

Jennings, S.G. (1983)- Extinction and liquid water content of fog at visible wavelengths. Appl. Opt., 22, 2514-2515.


Abstract


Extinction and Liquid Water Content Measurements at CO2 Laser wavelengths Extinction and Liquid Water Content Measurements at CO2 Laser wavelengths

Date added: 07/31/1987
Date modified: 07/01/2009
Filesize: 601.9 kB

Nolan, P.F., and Jennings, S.G. (1987). - Extinction and liquid water content measurements at CO2 laser wavelengths. J. Atmos. and Oceanic Technol., 4, 391 - 400.


Abstract

 

Measurements have been made of both extinction coefficients in an evaporating laboratory cloud at wavelength λ = 10.591 μm using a CO2 laser, and of liquid water content (LWC) at the center of the cloud using a continuous filtration LWC device. Cloud uniformity has been promoted and monitored within the laboratory chamber. The measurements give an overall linear relation between extinction and liquid water content independent of droplet-size distribution in reasonably good agreement with the Chýlek prediction. The measurements show significantly better agreement with the Chýlek prediction for the narrower cloud drop-size distributions. The broader size distribution data show an underestimate in extinction compared to the Chýlek prediction, providing the first experimental evidence for the large radius limit (radius 12 μm) in use of the Chýlek relation.

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

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

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


Abstract


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

Explaining global surface aerosol number concentrations in terms of primary emissions and particle f Explaining global surface aerosol number concentrations in terms of primary emissions and particle f

Date added: 01/31/2011
Date modified: 01/31/2011
Filesize: 972.89 kB

Spracklen, D. V., K. S. Carslaw, J. Merikanto, G. W. Mann, S. Pickering, J. A. Ogren, B. Andrews, U. Baltensperger, E. Weingartner, M. Boy, M. Kulmala, H. Lihavainen, J. Hatakka, N. Mihalopoulos, G. Kouvarakis, S. G. Jennings, C. O’Dowd, W. Birmili, A. Wiedensohler, R. Weller, J. Gras, P. Laj, R. Griffin, B. Bonn, and B. Bandy, Explaining global surface aerosol concentrations in terms of primary emissions and particle formation, Atmos. Chem. Phys., 10, 4775–4793, doi:10.5194/acp-10-4775-2010, 2010


 

Abstract

 

We synthesised observations of total particle number (CN) concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm−3 in the marine boundary layer and free troposphere (FT) and 1000–10 000 cm−3 in the continental boundary layer (BL). Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN obser-vations to evaluate primary and secondary sources of particle  number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46) but fail to explain the observed seasonal cycle (R2=0.1). The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88%) unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%). Simulated CN concentrations in the continental BL were also biased low (NMB=−74%) unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included  an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J , proportional to gas-phase sulfuric acid concentration to the power one) or kinetic-type mechanism (J proportional to sulfuric acid to the power two) with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3) than by increasing the number emission from primary anthropogenic sources (R2=0.18). The nucleation constants that resulted in best overall match between model and observed CN concentrations were consistent with values derived in previous studies from detailed case studies at individual sites. In our model, kinetic and activation-type nucleation parameterizations gave similar agreement with observed monthly mean CN concentrations.

 

Experiments on water drop interactions Experiments on water drop interactions

Date added: 09/06/1977
Date modified: 08/06/2009
Filesize: 1.27 MB

Jennings, S.G. (1977)- Experiments on water drop interactions. Phys. Ed., 12, 381-385.


Abstract

 

A series of experiments is described which demonstrate the interactions of water drops. These experiments were used in a project with second year undergraduates and should be easy to adapt for school use. Photographic, stroboscopic and droplet stream formation techniques are used. Droplet-droplet collisions and collisions with plane and curved air-water interfaces are involved. It is considered that the experiments provide a good basis for the understanding of the relative roles of kinetic energy and surface energy in governing water droplet behaviour.

Experimental studies of the effect of rough surfaces and air speed on aerosol deposition in a test chamber Experimental studies of the effect of rough surfaces and air speed on aerosol deposition in a test chamber

Date added: 07/31/2002
Date modified: 07/01/2009
Filesize: 915.07 kB

Lai, A.C.K., Byrne and AJH Goddard. Experimental studies of the effect of rough surfaces and air speed on aerosol deposition in a test chamber. Aerosol Science and Technology, 36: 973-982, 2002.


Abstract

 

Understanding the fate of particles indoors is important for human health assessment because deposited particles, unless resuspended, cannot be inhaled. To complement studies in real buildings, where control of variables is often difficult, an experimental test chamber facility (8 m3) was designed to study particle deposition under well-stirred conditions using monodisperse tracer aerosol particles in the range of 0.7 to 5.4 mum. The use of neutron-activatable tracers facilitated simultaneous surface sampling and aerosol concentration decay measurements.

 

Aerosol deposition on both smooth surfaces and regular arrays of three-dimensional roughness elements under 3 different airflow speeds was investigated in the test chamber.It was expected that the texture of the chamber surface would significantly influence particle deposition, but some counterintuitive results were observed: under the lowest airflow condition and for the smallest particle size, particle deposition onto rough samples was found to be less than on the corresponding smooth surfaces.

 

The ratio of particle deposition on rough surfaces relative to smooth surfaces increased with particle size and magnitude of airflow. For the largest particle size and airflow speed, particle deposition on the rough surfaces exceeded that on the smooth surfaces by a factor of 3.

Evolution of the aerosol, cloud and boundary layer dynamic and ACE2 Evolution of the aerosol, cloud and boundary layer dynamic and ACE2

Date added: 08/06/2000
Date modified: 07/01/2009
Filesize: 1.38 MB

Osborne, S.M., D.W.Johnson, R. Wood, B.J. Bandy, M.O. Andreae, C.D. O'Dowd, P. Glantz, K.J. Noone, C. Gerbig, J. Rudolph, T.S. Bates, and P.K. Quinn, Evolution of the aerosol, cloud and boundary layer dynamic and thermodynamic characteristics during the second Lagrangian experiment of ACE-2, Tellus, 52B(2), 375-400, 2000, (Ser. No. ACP149).


Abstract


We present observations from the 2nd Aerosol Characterisation Experiment where over a 29-h period between 16–18 July 1997 a tagged column of air was followed by a fully instrumented aircraft. The Lagrangian framework this offered made it possible to measure the evolution of the aerosol size distribution, the cloud structure and microphysics, and the dynamic and thermodynamic structure of the marine boundary layer within a polluted airmass advecting off northwest Europe over the sub-tropical North Atlantic Ocean. The salient observations are presented and analysed. Processes responsible for the evolution are suggested, but quantification of their respective rates must be taken up by future modelling studies. Stratocumulus capped the boundary layer throughout the period that produced negligible washout of aerosol. This implies that the conversion of a continental to a maritime airmass within the cloud-capped sub-tropical marine boundary layer is not controlled by the drizzle process but by entrainment from the free troposphere. We find evidence of processing of aerosol particles by stratocumulus cloud, in particular by aqueous-phase reactions. The processing of the aerosol, realised by modification of the aerosol size distribution in the particle diameter range 0.1–0.5 mum, was complicated by rapid changes in boundary layer height and structure, and also by entrainment of both polluted and relatively clean aerosol from the free troposphere. The cloud microphysics was affected by these changes in the boundary layer aerosol through changes in the cloud condensation nuclei activation spectra. The cloud microphysics was also strongly affected by changes in the dynamics of the boundary layer which included variations (e.g., diurnal) in cloud thickness and an increase in vertical wind speed. Thermodynamic changes within the boundary layer included decoupling due to an increasing sea-surface temperature and a change in the subsidence rate in the free troposphere superimposed on diurnal decoupling. Hypotheses have been devised so that future modellers can focus their efforts to either validate or invalidate potentially important processes.

 

Evidence of a natural marine source of oxalic acid and a possible link to glyoxal Evidence of a natural marine source of oxalic acid and a possible link to glyoxal

Date added: 03/14/2013
Date modified: 03/14/2013
Filesize: 410.96 kB
Rinaldi, Matteo, Stefano Decesari, Claudio Carbone, Emanuela Finessi, Sandro Fuzzi, Darius Ceburnis, Colin D. O’Dowd, Jean Sciare, John P. Burrows, Mihalis Vrekoussis, Barbara Ervens, Kostas Tsigaridis, and Maria Cristina Facchini, Evidence of a natural marine source of oxalic acid and a possible link to glyoxal, J. Geophys. Res., 116, D162,04, 12 PP., 2011, doi:10.1029/2011JD015659, 2011 __________________________________________________ Abstract. This paper presents results supporting the existence of a natural source of oxalic acid over the oceans. Oxalate was detected in “clean‐sector” marine aerosol samples at Mace Head (Ireland) (53°20’N, 9°54′W) during 2006, and at Amsterdam Island (37°48′S, 77°34′E) from 2003 to 2007, in concentrations ranging from 2.7 to 39 ng m−3 and from 0.31 to 17 ng m−3, respectively. The oxalate concentration showed a clear seasonal trend at both sites, with maxima in spring‐summer and minima in fall‐winter, being consistent with other marine biogenic aerosol components (e.g., methanesulfonic acid, non‐sea‐salt sulfate, and aliphatic amines). The observed oxalate was distributed along the whole aerosol size spectrum, with both a submicrometer and a supermicrometer mode, unlike the dominant submicrometer mode encountered in many polluted environments. Given its mass size distribution, the results suggest that over remote oceanic regions oxalate is produced through a combination of different formation processes. It is proposed that the cloud‐mediated oxidation of gaseous glyoxal, recently detected over remote oceanic regions, may be an important source of submicrometer oxalate in the marine boundary layer. Supporting this hypothesis, satellite‐retrieved glyoxal column concentrations over the two sampling sites exhibited the same seasonal concentration trend of oxalate. Furthermore, chemical box model simulations showed that the observed submicrometer oxalate concentrations were consistent with the in‐cloud oxidation of typical marine air glyoxal mixing ratios, as retrieved by satellite measurements, at both sites.

Evidence for Substantial Variations of Atmospheric Hydroxyl Radicals in the Past Two Decades Evidence for Substantial Variations of Atmospheric Hydroxyl Radicals in the Past Two Decades

Date added: 08/01/2001
Date modified: 07/01/2009
Filesize: 1.28 MB

Prinn, R. G.; Huang, J.; Weiss, R. F.; Cunnold, D. M.; Fraser, P. J.; Simmonds, P. G.; McCulloch, A.; Harth, C.; Salameh, P.; O'Doherty, S.; Wang, R. H. J.; Porter, L.; Miller, B. R.,Evidence for Substantial Variations of Atmospheric Hydroxyl Radicals in the Past Two Decades, Science, Volume 292, Issue 5523, pp. 1882-1888 (2001).


Abstract


The hydroxyl radical (OH) is the dominant oxidizing chemical in the atmosphere. It destroys most air pollutants and many gases involved in ozone depletion and the greenhouse effect. Global measurements of 1,1,1-trichloroethane (CH3CCl3, methyl chloroform) provide an accurate method for determining the global and hemispheric behavior of OH. Measurements show that CH3CCl3 levels rose steadily from 1978 to reach a maximum in 1992 and then decreased rapidly to levels in 2000 that were lower than the levels when measurements began in 1978. Analysis of these observations shows that global OH levels were growing between 1978 and 1988, but the growth rate was decreasing at a rate of 0.23 +/- 0.18% year-2, so that OH levels began declining after 1988. Overall, the global average OH trend between 1978 and 2000 was -0.64 +/- 0.60% year-1. These variations imply important and unexpected gaps in current understanding of the capability of the atmosphere to cleanse itself.

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

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

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


Abstract


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

 

Evaluation of mixing height retrievals from automatic profiling lidars and ceilometers in view of fu Evaluation of mixing height retrievals from automatic profiling lidars and ceilometers in view of fu

Date added: 08/12/2011
Date modified: 08/12/2011
Filesize: 1.59 MB

Haeffelin, M.,  F. Angelini, Y. Morille, G. Martucci, S. Frey, G. P. Gobbi, S. Lolli, C. D. O'Dowd, L. Sauvage, I. Xueref-Rémy, B. Wastine,  Evaluation of mixing height retrievals from automatic profiling lidars and ceilometers in view of future integrated networks in Europe, Bound. Lay. Met., DOI 10.1007/s10546-011-9643-z, 2011

 

The determination of the depth of daytime and nighttime mixing layers mustbe known very accurately to relate boundary-layer concentrations of gases or particles to upstream fluxes. The mixing-height is parametrized in numerical weather prediction models, so improving the determination of the mixing height will improve the quality of the estimated gas and particle budgets. Datasets of mixing-height diurnal cycles with high temporal and spatial resolutions are sought by various end users. Lidars and ceilometers provide vertical profiles of backscatter from aerosol particles. As aerosols are predominantly concentrated in the mixing layer, lidar backscatter profiles can be used to trace the depth of the mixing layer. Large numbers of automatic profiling lidars and ceilometers are deployed by meteorological services and other agencies in several European countries providing systems to monitor  the mixing height on temporal and spatial scales of unprecedented density. We investigate limitations and capabilities of existing mixing height retrieval algorithms by applying five different retrieval techniques to three different lidars and ceilometers deployed during two 1-month campaigns.We studied three important steps in the mixing height retrieval process, namely the lidar/ceilometer pre-processing to reach sufficient signal-to-noise ratio, gradient detection techniques to find the significant aerosol gradients, and finally quality control and layer attribution to identify the actual mixing height from multiple possible layer detections. We found that layer attribution is by far the most uncertain step. We tested different gradient detection techniques, and found no evidence that the first derivative, wavelet transform, and two-dimensional derivative techniques have different skills to detect one or multiple significant aerosol gradients from lidar and ceilometer attenuated backscatter. However, our study shows that, when mixing height retrievals from a ultraviolet lidar and a near-infrared ceilometer agreed, they were 25–40% more likely to agree with an independent radiosonde mixing height retrieval than when each lidar or ceilometer was used alone. Furthermore, we point to directions that may assist the layer attribution step, for instance using commonly available surface measurements of radiation and temperature to derive surface sensible heat fluxes as a proxy for the intensity of convective mixing. It is a worthwhile effort to pursue such studies so that within a few years automatic profiling lidar and ceilometer networks can be utilized efficiently to monitor mixing heights at the European scale. 

Evaluation of a three-dimensional chemical transport model (PMCAMx) in the European domain during the EUCAARI May 2008 campaign Evaluation of a three-dimensional chemical transport model (PMCAMx) in the European domain during the EUCAARI May 2008 campaign

Date added: 03/19/2013
Date modified: 03/19/2013
Filesize: 1.84 MB

Fountoukis, C., P. N. Racherla, H. A. C. Denier van der Gon, P. Polymeneas, P. E. Haralabidis, C. Pilinis, A. Wiedensohler, M. Dall’Osto, C. O'Dowd, and S. N. Pandis, Evaluation of a three-dimensional chemical transport model (PMCAMx) in the European domain during the EUCAARI May 2008 campaign, Atmos. Chem. Phys., 11, 10331–10347, 2011, doi:10.5194/acp-11-10331-2011, 2011.


Abstract. PMCAMx-2008, a detailed three-dimensional chemical transport model (CTM), was applied to Europe to simulate the mass concentration and chemical composition of particulate matter (PM) during May 2008. The model includes a state-of-the-art organic aerosol module which is based on the volatility basis set framework treating both primary and secondary organic components as semivolatile and photochemically reactive. The model performance is evaluated against high time resolution aerosol mass spectrometer (AMS) ground and airborne measurements. Overall, organic aerosol is predicted to account for 32% of total PM1 at ground level during May 2008, followed by sulfate (30 %), crustal material and sea-salt (14 %), ammonium (13 %), nitrate (7 %), and elemental carbon (4 %). The model predicts that fresh primary OA (POA) is a small contributor to organic PM concentrations in Europe during late spring, and that oxygenated species (oxidized primary and biogenic secondary) dominate the ambient OA. The Mediterranean region is the only area in Europe where sulfate concentrations are predicted to be much higher than the OA, while organic matter is predicted to be the dominant PM1 species in central and northern Europe. The comparison of the model predictions with the ground measurements in four measurement stations is encouraging. The model reproduces more than 94% of the daily averaged data and more than 87% of the hourly data within a factor of 2 for PM1 OA. The model tends to predict relatively flat diurnal profiles for PM1 OA in many areas, both rural and urban in agreement with the available measurements. The model performance against the high time resolution airborne measurements at multiple altitudes and locations is as good as its performance against the ground level hourly measurements. There is no evidence of missing sources of OA aloft over Europe during this period.

 

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

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

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


Abstract


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

 

Evaluating measurements new particle concentrations, source rates and spatial scales during .. Evaluating measurements new particle concentrations, source rates and spatial scales during ..

Date added: 07/31/2002
Date modified: 07/24/2009
Filesize: 863.78 kB

Kaarle Hameri , Colin O'Dowd, Claudia Hoell, Evaluating measurements new particle concentrations, source rates and spatial scales during coastal nucleation events using condensation particle counters. ,JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. D19, 8101, doi:10.1029/2001JD000411, 2002


Abstract


Condensation particle counters (CPCs), used to examine particle production in the coastal environment, are evaluated for their ability to differentiate ultrafine sizes between 3 and 10 nm, along with their ability to count high total particle number concentrations encountered during coastal nucleation events. Four ultrafine particles counters, with a 3 nm detection limit, were deployed in a spatial array comprising a triangular distribution with nodes approximately 100 m apart (two at 3 m height, one at 10 m). A fourth node was deployed at 20 m. The 10 m and 20 m node comprised additional CPCs with detection limits of 5 and 10 nm. Size cutoff efficiency calibrations were performed in the field, and all CPCs were found to be within the manufacturer's specifications. During the nucleation events it was found that peak particle concentrations of the order of 180,000 cm−3 were encountered, and as a result, coincidence calibrations were also performed in the laboratory. It was found that, at concentrations over 100,000 cm−3, the CPCs significantly underestimated the true concentrations by a factor of about 5–6. Total particle concentrations were also measured using a 30-times dilution system and an ultrafine CPC, along with integrated total concentration derived from the ultrafine Differential Mobility Particle Sizer (DMPS). Comparison of laboratory-derived corrections for coincidence and both the diluted CPC total concentrations and DMPS concentrations revealed very good agreement and confirmed that peak particle concentrations during coastal nucleation bursts result in new particle concentrations as high as 1.2 × 106 cm−3. The DMPS total concentration was somewhat lower than the diluted CPC concentration, suggesting that the recommended method of measuring such high concentrations is to dilute the sample significantly. The lower concentrations from the DMPS are partially due to the 10 min integration time being insufficient to resolve peaks seen by the CPC operated at 1 Hz. Taking the corrected concentrations in account, 3 nm particle source rates were calculated to be >105 cm−3 s−1. The spatial array of CPCs revealed that within the general coastal nucleation plume, there are numerous microplumes with spatial scales of the order of 10–100 m when sampling is conducted near the source region. Further from the source region these microplumes merge into the general coastal plume.

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

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

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


Abstract


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

 

European greenhouse gas emissions estimated from continuous atmospheric measurements and radon 222 at Mace Head, Ireland European greenhouse gas emissions estimated from continuous atmospheric measurements and radon 222 at Mace Head, Ireland

Date added: 07/31/2000
Date modified: 07/24/2009
Filesize: 1.37 MB

Biraud, S., Ciais, P., Ramonet, M., Simmonds, P.G., Kazan, V., Monfray, P., O'Doherty, S., Spain, T.G., and Jennings, S.G. (2000).European greenhouse gas emissions estimated from continuous atmospheric measurements and Radon 222 at Mace Head, Ireland. J. Geophys. Res., 105, 1351-1366.


Abstract


Flux estimates of CO2, CH4, N2O. and CFCs over western Europe have been inferred from continuous atmospheric records of these species at the atmospheric research station of Mace Head, Ireland. We use radon (222Rn) which has a fairly uniform source over continents as a reference compound to estimate unknown sources of other species. The correlation between each species and 222Rn is calculated for a suite of synoptic events that have been selected in the Mace Head record over the period 1996/97. In the following, we describe the method and its uncertainties, and we establish data selection criteria that minimize the influence of local sources over Ireland, in the vicinity of the station, in order to select synoptic events originating from western Europe. We estimate western European flux densities of 45-30 103 kg C km-2 month-1 during wintertime for CO2, of 4.8-3.5 10 kg CH4 km-2 yr-1, 475-330 kg N2O km-2 yr-1. 2.5-1.8 kg CFC-11 km-2 yr-1 for CFC-11, and 4.2-2.9 kg CFC-12 km-2 yr-1 for CFC-12. Our estimates are independent, although in good agreement with those produced by inventories, except for CFC- 1 where our estimate is much lower than the inventory.

European emissions of mercury derived from long-term obsercations at Mace Head, on the western Irish coast European emissions of mercury derived from long-term obsercations at Mace Head, on the western Irish coast

Date added: 08/01/2006
Date modified: 07/24/2009
Filesize: 185.84 kB

Slemr F, R. Ebinghaus, P.G. Simmonds and S.G. Jennings, European emissions of mercury derived from long-term observations at Mace Head, on the western Irish coast, Atmos. Environ., 40, 6966-6974, 2006.


Abstract


Many emission inventories for mercury have been compiled but rarely constrained using observations of ambient air concentrations with a known quality. In this paper, we derive Hg/CO, Hg/halocarbon, and Hg/CH4 emission ratios from pollution episodes observed during the long-term mercury monitoring at the Mace Head Atmospheric Research Station in Ireland. The average Hg/CO emission ratio from 15 pollution episodes with air originating from the European continent observed between 1996 and 2003 was 0.0050±0.0021 ng m-3 ppbv-1, i.e. (5.5±2.3) x 10-7mol/mol, which is almost identical to the ratio reported recently for the continental plumes of eastern Asia. Mercury correlated also with CFCl3 (CFC-11), CF2Cl2 (CFC-12), CH3CCl3, CCl4, CCl2FCF2Cl (CFC-113), CHCl3, N2O, and CH4 during the pollution episodes. The mercury emissions calculated from the emission ratios and the European emissions of the above gases are in reasonable agreement with the estimated anthropogenic total mercury emissions of 250t/yr in 1995. However, the measurements encompass almost exclusively elemental mercury whose anthropogenic emissions are estimated to be only 152 t yr-1. Several hypotheses are proposed to explain this discrepancy, such as natural sources, underestimation of the emissions of elementary mercury, and erroneous speciation of anthropogenic emissions.

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

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

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


Abstract


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

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

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

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


Abstract

 

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

EUCAARI ion spectrometer measurements at 12 European sites – analysis of new-particle formation even EUCAARI ion spectrometer measurements at 12 European sites – analysis of new-particle formation even

Date added: 11/10/2010
Date modified: 11/10/2010
Filesize: 2.55 MB

Manninen, H. E, .T. Nieminen, E. Asmi, S. Gagné, S. Häkkinen, K. Lehtipalo, P. Aalto, M. Vana, A. Mirme, S. Mirme, U. Hõrrak, C. Plass-Dülmer, G. Stange, G. Kiss, A. Hoffer, N. Tör\H{o}, M. Moerman, B. Henzing, G. de Leeuw, M. Brinkenberg, G. N. Kouvarakis, A. Bougiatioti, N. Mihalopoulos, C. O'Dowd, D. Ceburnis, A. Arneth, B. Svenningsson, E. Swietlicki, L. Tarozzi, S. Decesari, M. C. Facchini, W. Birmili, A. Sonntag, A. Wiedensohler, J. Boulon, K. Sellegri, P. Laj, M. Gysel, N. Bukowiecki, E. Weingartner, G. Wehrle, A. Laaksonen, A. Hamed, J. Joutsensaari, T. Petäjä, V.-M. Kerminen, and M. Kulmala, EUCAARI ion spectrometer measurements at 12 European sites – analysis of new-particle formation events,
Atmos. Chem. Phys., 10, 7907–7927, doi:10.5194/acp-10-7907-2010, 2010


  

We present comprehensive results on continuous atmospheric cluster and particle measurements in the size range 

1–42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. We focused on characterizing the spatial and temporal variation of new particle formation events and relevant particle formation parameters across Europe. Different types of air ion and cluster mobility spectrometers were deployed at 12 field sites across Europe from March 2008 to May 2009. The measurements were conducted in a wide variety of environments, including coastal and continental locations as well as sites at different altitudes (both in the boundary layer and the free troposphere). New particle formation events were detected at all of the 12 field sites during the year-long measurement period. From the data, nucleation and growth rates of newly formed particles were determined for each environment. In a case of parallel ion and neutral cluster measurements, we could also estimate the relative contribution of ion-induced and neutral nucleation to  the total particle formation. The formation rates of charged particles at 2 nm accounted for 1–30% of the corresponding total particle formation rates. As a significant new result, we found out that the total particle formation rate varied much more between the different sites than the formation rate of charged particles. This work presents, so far, the most comprehensive effort to experimentally characterize nucleation and growth of atmospheric molecular clusters and nanoparticles at ground-based observation sites on a continental scale.

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

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

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


Abstract


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

 

Estimating relationships between air mass origin and chemical composition Estimating relationships between air mass origin and chemical composition

Date added: 08/06/2001
Date modified: 07/27/2009
Filesize: 1.49 MB

Methven, J., M. Evans, P. Simmonds, and G. Spain (2001), Estimating relationships between air mass origin and chemical composition, J. Geophys. Res., 106(D5), 5005–5019.


Abstract


Observations of a chemical at a point in the atmosphere typically show sudden transitions between episodes of high and low concentration. Often these are associated with a rapid change in the origin of air arriving at the site. Lagrangian chemical models riding along trajectories can reproduce such transitions, but small timing errors from trajectory phase errors dramatically reduce the correlation between modeled concentrations and observations. Here the origin averaging technique is introduced to obtain maps of average concentration as a function of air mass origin for the East Atlantic Summer Experiment 1996 (EASE96, a ground-based chemistry campaign). These maps are used to construct origin averaged time series which enable comparison between a chemistry model and observations with phase errors factored out. The amount of the observed signal explained by trajectory changes can be quantified, as can the systematic model errors as a function of air mass origin. The Cambridge Tropospheric Trajectory model of Chemistry and Transport (CiTTyCAT) can account for over 70% of the observed ozone signal variance during EASE96 when phase errors are side-stepped by origin averaging. The dramatic increase in correlation (from 23% without averaging) cannot be achieved by time averaging. The success of the model is attributed to the strong relationship between changes in ozone along trajectories and their origin and its ability to simulate those changes. The model performs less well for longer-lived chemical constituents because the initial conditions 5 days before arrival are insufficiently well known.

 

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

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

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


Abstract


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

 

Equilibrium Size of Atmospheric Aerosol Sulfates as a Function of Particle Acidity and Ambient Relative Humidity Equilibrium Size of Atmospheric Aerosol Sulfates as a Function of Particle Acidity and Ambient Relative Humidity

Date added: 07/31/1993
Date modified: 07/01/2009
Filesize: 557.48 kB

Kelly, B.P., & Koutrakis, P. (1993)- Equilibrium size of atmospheric aerosol sulphates as a function of particle acidity and ambient relative humidity. J. Geophy. Res. 98, pp. 7141-7147.


Abstract


Acid aerosol events in Uniontown, Pennsylvania, were studied during the summer of 1990. Size-fractionated acid aerosols were collected using a microorifice cascade impactor. The collected samples were analyzed for hydrogen, sulfate, nitrate, and ammonium ion concentrations. These measurements show evidence of a relationship between the mass median geometric aerodynamic diameter of sulfate particles and both particle acid content (H+/SO4=) and ambient relative humidity. Sulfate particle size increases with both increasing acid content and relative humidity. Considering the uncertainties involved, the growth of atmospheric sulfate particles observed in this study was found to be in good agreement with that predicted on the basis of laboratory-derived data. To our knowledge, this is the first time that such a relationship has been observed under real atmospheric conditions. Therefore the results of this study suggest that laboratory experiments and thermodynamic calculations can be used in order to understand the chemistry of atmospheric sulfates and their impacts on visibility reduction. In addition, we present evidence to suggest that the chemical composition of acid aerosol particles may be related to the ambient relative humidity.

Emissions of CH3Br, organochlorines, and organoiodines from temperate macroalgae Emissions of CH3Br, organochlorines, and organoiodines from temperate macroalgae

Date added: 08/05/2001
Date modified: 07/01/2009
Filesize: 249.05 kB

Baker1 J.M.; Sturges W.T.1; Sugier J.; Sunnenberg G.; Lovett A.A.; Reeves C.E.; Nightingale P.D.; Penkett S.A., Emissions of CH3Br, organochlorines, and organoiodines from temperate macroalgae, Chemosphere: Global Science Change, Volume 3, Number 1, January 2001 , pp. 93-106(14)


Abstract


The production rates of a range of low molecular weight halogenated organics have been determined in cultures of five temperate species of macroalgae collected from the north coast of Norfolk, England. Compounds studied included CH3Br, the chlorinated organics CH3Cl, CH2Cl2 and CHCl3, and the iodinated organics CH3I, C2H5I, and CH2ClI. Measurements of a wider range of halocarbon concentrations in an isolated rockpool and in air over the seaweed bed were also conducted to evaluate the local impact of the seaweeds on halocarbon concentrations in the natural environment. Estimates for the global emissions of some of the key halogenated compounds from macroalgae have been derived. In general macrophytes appear not to be globally significant producers of the particular halocarbons studied. In coastal regions, however, the impact on local atmospheric composition and chemistry could be greater.

 

Emissions from Ships with respect to Their Effects on Clouds Emissions from Ships with respect to Their Effects on Clouds

Date added: 08/06/2000
Date modified: 07/01/2009
Filesize: 302.93 kB

Hobbs, P.V., T.J. Garrett, and co-authors, 2000: Emissions from ships with respect to their effects on clouds, J. Atmos. Sci., 57, 2570-2590


Abstract


Emissions of particles, gases, heat, and water vapor from ships are discussed with respect to their potential for changing the microstructure of marine stratiform clouds and producing the phenomenon known as ship tracks. Airborne measurements are used to derive emission factors of SO2 and NO from diesel-powered and steam turbine-powered ships, burning low-grade marine fuel oil (MFO); they were ∼15-89 and ∼2-25 g kg-1 of fuel burned, respectively. By contrast a steam turbine-powered ship burning high-grade navy distillate fuel had an SO2 emission factor of ∼6 g kg-1. Various types of ships, burning both MFO and navy distillate fuel, emitted from ∼4 X 1015 to 2 X 1016 total particles per kilogram of fuel burned (∼4 X 1015-1.5 X 1016 particles per second). However, diesel-powered ships burning MFO emitted particles with a larger mode radius (∼0.03-0.05 μm) and larger maximum sizes than those powered by steam turbines burning navy distillate fuel (mode radius ∼0.02 μm). Consequently, if the particles have similar chemical compositions, those emitted by diesel ships burning MFO will serve as cloud condensation nuclei (CCN) at lower supersaturations (and will therefore be more likely to produce ship tracks) than the particles emitted by steam turbine ships burning distillate fuel. Since steam turbine-powered ships fueled by MFO emit particles with a mode radius similar to that of diesel-powered ships fueled by MFO, it appears that, for given ambient conditions, the type of fuel burned by a ship is more important than the type of ship engine in determining whether or not a ship will produce a ship track. However, more measurements are needed to test this hypothesis. The particles emitted from ships appear to be primarily organics, possibly combined with sulfuric acid produced by gas-to-particle conversion of SO2. Comparison of model results with measurements in ship tracks suggests that the particles from ships contain only about 10% water-soluble materials. Measurements of the total particles entering marine stratiform clouds from diesel-powered ships fueled by MFO, and increases in droplet concentrations produced by these particles, show that only about 12% of the particles serve as CCN. The fluxes of heat and water vapor from ships are estimated to be ∼2-22 MW and ∼0.5-1.5 kg s-1, respectively. These emissions rarely produced measurable temperature perturbations, and never produced detectable perturbations in water vapor, in the plumes from ships. Nuclear-powered ships, which emit heat but negligible particles, do not produce ship tracks. Therefore, it is concluded that heat and water vapor emissions do not play a significant role in ship track formation and that particle emissions, particularly from those burning low-grade fuel oil, are responsible for ship track formation. Subsequent papers in this special issue discuss and test these hypotheses.

 

Emission rates of C8–C15 VOCs from seaweed and sand in the inter-tidal zone at Mace Head, Irela Emission rates of C8–C15 VOCs from seaweed and sand in the inter-tidal zone at Mace Head, Irela

Date added: 08/07/2002
Date modified: 07/27/2009
Filesize: 167.86 kB

Emission rates of C8 - C15 VOCs from seaweed and sand in the inter-tidal zone at Mace Head, Ireland (2002) J.H. Sartin, C.J. Halsall, S. Hayward and C.N. Hewitt, Atmospheric Environment , 36, 5311 - 5321


Abstract


Emission fluxes for a range of C8-C15 volatile organic compounds (VOCs) were determined from the seaweed Fucus spiralis (spiral wrack) and an adjacent sand surface during low tide on the coastline of Mace Head, Ireland. These two surface types, assessed using dynamic flux chamber systems, are typical of the Mace Head inter-tidal zone. A range of n-alkanes and oxygenates were routinely identified in the measurement of chamber air. Examination of the odd/even n-alkane ratios and use of the carbon preference index (CPI) suggested a biogenic source for these compounds (CPIs >2 in for all samples). Fluxes of n-pentadecane, the most predominant n-alkane, ranged from 0.2 to 5.1mugm-2h-1 (0.9-24nmolm-2h-1), while oxygenates such as nonanal and decanal had fluxes ranging from <0.1 to 4.4mugm-2h-1 (<0.1-31nmolm-2h-1) and <0.1 to 4.6mugm-2h-1 (<0.1-30nmolm-2h-1), respectively. Seaweed emission rates for n-pentadecane were correlated with photosynthetically active radiation (PAR) (rs=0.94) while emissions from sand showed correlation with temperature (rs=0.85). This suggests a possible biochemical route controlling the release of n-pentadecane from spiral wrack, and temperature-driven volatilisation from sand. Volatilisation from residual seawater trapped in the sand may explain the comparable flux of both n-alkanes and oxygenates from this surface. Unlike the n-alkanes, oxygenate fluxes from sand correlate with PAR, suggesting a photodependent production from organic carbon residues present in seawater. Comparison with previous flux estimates from coastal seawater indicates that the two source types (Fucus spiralis and bare sand) are significant but not dominant sources of these VOCs.

 

Elemental and organic carbon in PM10 a one year measurement campaign within the European Monitoring and Evaluation Programme EMEP Elemental and organic carbon in PM10 a one year measurement campaign within the European Monitoring and Evaluation Programme EMEP

Date added: 08/01/2007
Date modified: 07/27/2009
Filesize: 2.18 MB

Yttri, K.E., W. Aas, A. Bjerke, J.N. Cape, F. Cavalli, D. Ceburnis, C. Dye, L. Emblico, M.C. Facchini, C. Forster, J.E. Hanssen, S.G. Jennings, W. Maenhaut, J.P. Putaud, and K. Torseth, Elemental and organic carbon in PM10: a one year measurement campaign within the European Monitoring and Evaluation Programme EMEP, Atmos. Chem. Phys., 7, 5711-5725, 2007.


Abstract


In the present study, ambient aerosol (PM10) concentrations of elemental carbon (EC), organic carbon (OC), and total carbon (TC) are reported for 12 European rural background sites and two urban background sites following a one-year (1 July 2002–1 July 2003) sampling campaign within the European Monitoring and Evaluation Programme, EMEP http://www.emep.int/). The purpose of the campaign was to assess the feasibility of performing EC and OC monitoring on a regular basis and to obtain an overview of the spatial and seasonal variability on a regional scale in Europe.

Analyses were performed using the thermal-optical transmission (TOT) instrument from Sunset Lab Inc., operating according to a NIOSH derived temperature program. The annual mean mass concentration of EC ranged from 0.17±0.19 μg m−3 (mean ± SD) at Birkenes (Norway) to 1.83±1.32 μg m−3 at Ispra (Italy). The corresponding range for OC was 1.20±1.29 μg m−3 at Mace Head (Ireland) to 7.79±6.80 μg m−3 at Ispra. On average, annual concentrations of EC, OC, and TC were three times higher for rural background sites in Central, Eastern and Southern Europe compared to those situated in the Northern and Western parts of Europe. Wintertime concentrations of EC and OC were higher than those recorded during summer for the majority of the sites. Moderate to high Pearson correlation coefficients (rp) (0.50–0.94) were observed for EC versus OC for the sites investigated. The lowest correlation coefficients were noted for the three Scandinavian sites: Aspvreten (SE), Birkenes (NO), and Virolahti (FI), and the Slovakian site Stara Lesna, and are suggested to reflect biogenic sources, wild and prescribed fires. This suggestion is supported by the fact that higher concentrations of OC are observed for summer compared to winter for these sites. For the rural background sites, total carbonaceous material accounted for 30±9% of PM10, of which 27±9% could be attributed to organic matter (OM) and 3.4±1.0% to elemental matter (EM). OM was found to be more abundant than SO42- for sites reporting both parameters.

Electrostatic Deposition in ionic Diffussion Electrostatic Deposition in ionic Diffussion

Date added: 08/31/1968
Date modified: 07/21/2009
Filesize: 1.69 MB
F. Anderson, P.J Nolan and T.C. O'Connor, Electrostatic Deposition in ionic Diffussion, Volume 66, Section A, No. 5, 1968

Abstract

 

Errors in the determination of ionic diffusion coefficients caused by the neglect of electrostatic deposition are examined. Correction formulae applicable to low ionic concentrations are derived for cylindrical channels. These are similiar to the Fuchs formulae for rectangular channels. Formulae applicable in the case of high ionic concentration are also derived.

For singly charged particles the correction tot the diffusion coefficient under the usual experimental conditions is about two or three per cent. The error becomes large when the number electronic charges per ion aproaches 100. Previous Dublin experiments with multiply charged nuclei are examined in this connection and corrections applied. The Corrections do not invalidate the main conclusion of these experiments that the Einstein equation B=D/KT does not apply in the absence of charge equilibrium.

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