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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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Use of an Average complex refractive index in atmospheric propagation calculations Use of an Average complex refractive index in atmospheric propagation calculations

Date added: 08/01/1978
Date modified: 07/08/2009
Filesize: 932.35 kB
. B. Gillespie, S. G. Jennings, and J. D. Lindberg, "Use of an average complex refractive index in atmospheric propagation calculations," Appl. Opt. 17, 989-991 (1978)

Abstract

 

In most atmospheric propagation calculation it is generally ssumed that atmospheric dust is composed of homogeneous spherical particles all with the same average complex refractive index and all distributed by the same size distribution. As pointed out by Bergstrom, it is perhaps more realisitc to assume that since diiferent optical constants and each component will have an associated size distribution characteristic of its production. In particular, the free carbon type particles and the soil derived particles should be different. Previous work in our laboratory  with commericallly available cascade impactors has shown that, for some minerals characteristic of the local envirorment, the imaginary refractive index of desert dust is a strong function of particle size.

Variations of CN number concentrations with respect to meteorological conditions at Mace Head, Variations of CN number concentrations with respect to meteorological conditions at Mace Head,

Date added: 08/07/1998
Date modified: 07/23/2009
Filesize: 56.9 kB

Kleefeld C.; Geever M.; Jennings S.G.; Maring H.,Variations of CN number concentrations with respect to meteorological conditions at mace head, Ireland,Journal of Aerosol Science, Volume 29, Supplement 1, September 1998 , pp. 203-203(1)


Verification of a Linear Relation between IR Extinction Absorption and Liquid Water Content of Fogs Verification of a Linear Relation between IR Extinction Absorption and Liquid Water Content of Fogs

Date added: 08/01/1979
Date modified: 07/27/2009
Filesize: 761.93 kB

Pinnick, R. G.; Jennings, S. G.; Chýlek, Petr; Auvermann, H. J., Verification of a Linear Relation between IR Extinction, Absorption and Liquid Water Content of Fogs., Journal of Atmospheric Sciences, vol. 36, Issue 8, pp.1577-1586


Abstract


A linear relationship, independent of the form of the size-distribution, between extinction at wave-lengths around = 11 µm, absorption around = 3.8 and 9.5 µm, and liquid water content of atmospheric fogs has been verified using 341 droplet size distribution measurements made under a variety of meteorological conditions. The results suggest that integrated liquid water content along a path in fog can be determined from measurement of CO2 laser ( = 10.6 µm) transmission along the path, and that liquid water content at a particular point in fog can be inferred from in situ measurement of fog-droplet absorption with a deuterium fluoride laser ( = 3.8 µm) or a suitably tuned C02 laser ( = 9.5 µm) spectrophone.

Vertical Inhomogeneity in Atmospheric Fog and Haze and it's effects on IR extinction Vertical Inhomogeneity in Atmospheric Fog and Haze and it's effects on IR extinction

Date added: 08/01/1978
Date modified: 07/08/2009
Filesize: 2.32 MB
Pinnick, R. G.; Hoihjelle, D. L.; Stenmark, E. B.; Lindberg, James D., Vertical inhomogeneity in atmospheric fog and haze and its effects on infrared extinction, J. Opt. Soc. Am, Vol.68, Page 540

Abstract

 

The presence of atmospheric fog and haze is important to radiative transfer in the atmosphere. For quantitative estimates of scattering and absorption by fod and haze particles, the size distribution is needed. Previously, fog and haze particulate size distributions have been measured by impaction techniques (Garland, 1971; Pilie, 1975; Krasikov and Chikirova, 1956; Kumai, 1973; low, 1975; May, 1961; barteneva and Polyakova, 1965; and Goodman, 1977), by collection of particles on spiderwebs (Arnulf et al., 1957), by a laser hologram camera (Kumkelm, 1971), and by light-scattering single particle counters (Eldridge, 1961; Laktionov, 1967). All of these techniques have serious limitations which restrict their usefulness and require measurements made with them to be regarded with caution. For example, impaction techniques involve laborious microsope measuremtn of droplets or droplet replicas, and corrections must be made to obtain true droplet size. Furthermore, impaction collection efficiencies must be applied to obtain relative particle concentrations.

 

In this article we present measurements of the size distribution of fog and haze particles made with a balloon-borne light-scattering single-particle counter, with emphasis on their effect on Infrared radiation. The primary advantages of using a light-scattering counter is that the measurement is donw in situ in real time, with minimal disturbance to the particles during measurement. Also, measurment of vertical structure is possible with this technique because a statistically significant size distribution measurement can be completed in a relatively short time (on the order of 1/2 minute), permitting a vertical upleg and lownleg to 200m altitude to be completed in 15 to 30 minutes. Measurements made during upleg and downleg portions of each tranverse show that temporal changes during such times scales were relatively small compared to vertical changes for most measurement periods.

Results from measurement of four haze and fog profiles presented here are typical of 19 profiles measured during February 1976 near Grafenwohr, a town located 100 km north of Nurnberg near the eastern border of West Germany. The local terrain consists of rollong hills and is partially forested; some of the land is tilled for farming.

Vertical Structure in Atmospheric Fog and Haze and Its Effects on Visible and Infrared Extinction Vertical Structure in Atmospheric Fog and Haze and Its Effects on Visible and Infrared Extinction

Date added: 08/01/1978
Date modified: 07/08/2009
Filesize: 1004.22 kB
R. G. Pinnick, D. L. Hoijelle, G. Fernandez, E. B. Stenmark, J. D. Lindberg, G. B. Hoidale, and S. G. Jennings,, "Vertical structure in atmospheric fog and haze and its effects on visible and infrared extinction," J. Atmos. Sci.35, 2020 (1978).

Abstract

 

Vertical structure of the size distribution and number concentration of particulates in atmospheric fog and haze near Grafenwöhr, West Germany, were measured with a balloonborne light-scattering aerosol counter for periods spanning parts of eight days in February 1976. For haze (5 km visibility) conditions, little vertical variation is seen; but for low visibility (<1 km) fog conditions, significant vertical increases in concentration of droplets with radii larger than 4 μm are seen over the first 150 m altitude. For haze, the particle size distribution is approximated by a log-normal with geometric mean radius rg ≈ 0.2 μm and geometric standard deviation  σo ≈1.9. For fog, a bimodal distribution is found with a relative maximum for the larger particle mode at radii of 4 to 6 μm and corresponding values rg ≈ 5 m and σo ≈1.6; the smaller particle mode has values of rg ≈ 0.3 μm to rg ≈ 0.6 μm and σo  ≈1.8 to ≈2.5. Liquid water content values for haze and fog range from 10-4 to 0.45 g m-3. Extinction calculated from the particle size distributions shows an approximate 1/ λ wavelength dependence for haze conditions, but nearly neutral (wavelength independent) extinction for heavy fog. A correlation exists between calculated particulate extinction and calculated liquid water content, independent of particle size distribution, for the fogs and hues studied.

Volatility of aerosols at Mace Head on the west coast of Ireland Volatility of aerosols at Mace Head on the west coast of Ireland

Date added: 09/03/1990
Date modified: 07/08/2009
Filesize: 668.3 kB

Jennings, S.G., and O'Dowd, C.D. (1990). - Volatility of aerosols at Mace Head on the west coast of Ireland. J. Geophys. Res., 95, 13,937 - 13,948.


Abstract


Volatile properties of maritime and modified maritime aerosol were measured at the remote site at Mace Head (53°19′N, 9°54′W) on the west coast of Ireland, located on the eastern edge of the North Atlantic Ocean. The volatility measurements were made with a light-scattering counter equipped with a temperature-controlled heated inlet. The work extends the temperature range from 300°C to 850°C for the first time for aerosol volatility studies. Representative measurements made over the period of about a year show that the submicrometer particles with radius <0.2 μm are highly volatile for the maritime aerosol and show temperature fractionation features of ammonium sulfate (or ammonium bisulfate). It is estimated that 85–95% of this size fraction (by volume) is composed of these sulfates. For the higher temperatures, temperature-fractionation characteristics of sodium chloride are shown for the supermicron and also the submicron maritime particles. About 80% of the particle size interval of 0.3–1.5 μm radius is composed of sodium chloride. The temperature profile curves for the modified maritime aerosol, which has made a partial traverse overland, do not display definitive features characteristic of known atmospheric constituents such as ammonium sulfate or sodium chloride, but rather properties indicative of mixtures of these species with other unknown constituents. For both airmasses, between about 5% and 30% (by volume) of the aerosol particles remain involatile at least up to a temperature of 850°C.

Volatility of Aerosols in the Arid Southwestern United States Volatility of Aerosols in the Arid Southwestern United States

Date added: 07/31/1987
Date modified: 07/08/2009
Filesize: 1.19 MB

Pinnick, R.G., Jennings, S.G., and Fernandez, G. (1987). - Volatility of aerosols in the arid south western United States. J. Atmos. Sci., 44, 391 - 400.


Abstract

 

Volatile properties of aerosols at an isolated rural site in south-central New Mexico were measured with a light-scattering particle counter equipped with a temperature-controlled heated inlet. Intermittent measurements throughout a one-year period show that submicron particles are highly volatile and display temperature-fractionation characteristics of ammonium sulfate or bisulfate. It is estimated that 60-98 percent of the submicron aerosol fraction (by mass) is composed of these sulfates. Larger supermicron particles with radii greater than 0.4 micron, which are composed mostly of quartz and clay minerals of soil origin, are relatively involatile.

Volatility of Elemental Carbon Volatility of Elemental Carbon

Date added: 07/31/1994
Date modified: 07/23/2009
Filesize: 423.53 kB
Jennings, S.G., O'Dowd, C.D., Cooke, W.F., Sheridan, P.J. and Cachier, (1994). - Volatility of elemental carbon. Geophys. Res. Letts., 21, 1719 - 1722.

Abstract


A volatility technique whereby aerosol particles are heated to the relatively high temperature of 860 °C is used to infer the presence of elemental carbon in polluted air masses in the vicinity of the west coast of Ireland. The volume of elemental carbon for submicrometre sized particles contained in the aerosol is estimated from the fall off in number concentration at a critical onset temperature of about 730 −735 °C, as also obtained for laboratory carbon ink aerosol. The technique permits determination of the elemental carbon volume percentage of the total fine aerosol volume, and an estimation of the abundance of elemental carbon contained within the black carbon fraction of the atmospheric aerosol. Supplementary black carbon mass concentration measurements were obtained using a thermal method and an aethalometer absorption method. The work suggests that elemental carbon can be identified using the volatility technique and that it can yield size-segregated information on the fraction of elemental carbon in atmospheric aerosol.

Volatility of Elemental Carbon Volatility of Elemental Carbon

Date added: 07/31/1994
Date modified: 07/13/2009
Filesize: 423.53 kB
Jennings, S.G., O'Dowd, C.D., Cooke, W.F., Sheridan, P.J. and Cachier, (1994). - Volatility of elemental carbon. Geophys. Res. Letts., 21, 1719 - 1722.

Abstract


A volatility technique whereby aerosol particles are heated to the relatively high temperature of 860 °C is used to infer the presence of elemental carbon in polluted air masses in the vicinity of the west coast of Ireland. The volume of elemental carbon for submicrometre sized particles contained in the aerosol is estimated from the fall off in number concentration at a critical onset temperature of about 730 −735 °C, as also obtained for laboratory carbon ink aerosol. The technique permits determination of the elemental carbon volume percentage of the total fine aerosol volume, and an estimation of the abundance of elemental carbon contained within the black carbon fraction of the atmospheric aerosol. Supplementary black carbon mass concentration measurements were obtained using a thermal method and an aethalometer absorption method. The work suggests that elemental carbon can be identified using the volatility technique and that it can yield size-segregated information on the fraction of elemental carbon in atmospheric aerosol.

Weather: Understanding rainfall Weather: Understanding rainfall

Date added: 08/01/1971
Date modified: 07/22/2009
Filesize: 336.23 kB
Weather: Understanding rainfall,1971
Abstract

Wet properties affecting Atmospheric Aerosols Wet properties affecting Atmospheric Aerosols

Date added: 08/01/1998
Date modified: 07/10/2009
Filesize: 6.2 MB
Jennings. S.G, Wet properties affecting Atmospheric Aerosols, 1998, Atmospheric Particles, Pg 476-502, Wiley & Sons

Abstract

 

The origin of atmospheric particles can be either anthropogenic (man-made) or natural. Primary particles are those which are emitted into the atmosphere as particles such as black carbon and organic particles in smoke plumes, soil dust particles, sea spray and volcanic particles, etc Secondary particles are formed from gas-to-particle coversion processes in the atmosphere- such as sulphates(from SO2), Nitreates (from (NOx) and secondary organics (from gaseous hydro-carbons)

Wet properties affecting Atmospheric Aerosols Wet properties affecting Atmospheric Aerosols

Date added: 08/01/1998
Date modified: 09/11/2009
Filesize: 6.2 MB
Jennings. S.G, Wet properties affecting Atmospheric Aerosols, 1998, Atmospheric Particles, Pg 476-502, Wiley & Sons

Abstract

 

The origin of atmospheric particles can be either anthropogenic (man-made) or natural. Primary particles are those which are emitted into the atmosphere as particles such as black carbon and organic particles in smoke plumes, soil dust particles, sea spray and volcanic particles, etc Secondary particles are formed from gas-to-particle coversion processes in the atmosphere- such as sulphates(from SO2), Nitreates (from (NOx) and secondary organics (from gaseous hydro-carbons)

Whitecap Coverage: Measurements from the North Atlantic Whitecap Coverage: Measurements from the North Atlantic

Date added: 12/10/2008
Date modified: 11/01/2009
Filesize: 198.39 kB
Callaghan, A., G. de Leeuw, L. Cohen, C.D. O’Dowd, Oceanic Whitecap Coverage: Measurements from the North Atlantic, Geophys. Res. Letts., doi:10.1029/2008GL036165, 2008

Abstract

 

Sea surface images obtained during the 2006 Marine Aerosol Production (MAP) campaign in the North East Atlantic were analysed for values of percentage whitecap coverage (W). Values of Ware presented for wind speeds up to circa 23 m s-1. The W data were divided into two overlapping groups and a piecewise,  wind-speed-only parameterization of W is proposed that is valid for wind speeds between 3.70 m s-1 and 23.09 m s-1. Segregation of data points based upon a 2.5 hour wind history acted to decrease data scatter at wind speeds above approximately 9.25 m s-1. At these wind speeds W values were greater for decreasing wind speeds than for increasing wind speeds. No clear wind history effect was observed at wind speeds below 9.25 m s-1

Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray

Date added: 08/25/2011
Date modified: 11/17/2011
Filesize: 714.57 kB

Gantt, B, N. Meskhidze, M.C. Facchini, M. Rinaldi, D. Ceburnis, C.D. O’Dowd, Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray, Atmos. Chem. Phys., 11, 1–13, 2011, www.atmos-chem-phys.net/11/1/2011/doi:10.5194/acp-11-1-2011


Abstract: For oceans to become a significant source of primary organic aerosol, sea spray must be highly enriched with organics relative to the bulk seawater.  We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic mass fraction of sea spray aerosol (OMss).  To test this hypothesis, we developed a new marine primary organic aerosol emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed.  The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll-a, dissolved organic carbon, and particulate organic carbon.  Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 meter wind speed and surface chlorophyll-a concentration ([Chl-a]) are the most consistent predictors of OMss.  This relationship, combined the published aerosol size dependence of OMss, resulted in a new parameterization for the organic carbon fraction of sea spray.  Global marine primary organic emission is investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl-a], and modeled 10 meter winds.  Analysis of model simulations show that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.8 to 5.6 Tg C yr-1.  This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere.

 

Wind Speed Influences on Marine Aerosol Optical Depth Wind Speed Influences on Marine Aerosol Optical Depth

Date added: 11/10/2010
Date modified: 11/10/2010
Filesize: 2.04 MB

O’Dowd, C., C. Scannell, J. Mulcahy & S. G. Jennings,   Wind Speed Influences on Marine Aerosol Optical Depth. Adv. in Meteorol., Article ID 830846,  2010. doi:10.1155/2010/830846, 2010.


TheMulcahy (Mulcahy et al., 2008) power-law parameterization, derived at the coastal Atlantic stationMace Head, between clean marine aerosol optical depth (AOD) and wind speed is compared to open ocean MODIS-derived AOD versus wind speed. The reported AOD versus wind speed (U) was a function of 

U2. The open ocean MODIS-derived AOD at 550nm and 860nm wavelengths, while in good agreement with the general magnitude of the Mulcahy parameterization, follows a power-law with the exponent ranging from 0.72 to 2.47 for a wind speed range of 2–18ms1. For the four cases examined, some MODIS cases underestimated AOD while other cases overestimated AOD relative to the Mulcahy scheme. Overall, the results from MODIS support the general power-law relationship of Mulcahy, although some linear cases were also encountered in the MODIS dataset. Deviations also arise between MODIS andMulcahy at higher wind speeds (>15ms1), whereMODIS-derived AOD returns lower values as compared to Mulcahy. The results also support the suggestion than wind generated sea spray, under moderately high winds, can rival anthropogenic pollution plumes advecting out into marine environments with wind driven AOD contributing to AOD values approaching 0.3.

Wind-driven influences on aerosol light scattering in north-east Atlantic air Wind-driven influences on aerosol light scattering in north-east Atlantic air

Date added: 03/12/2013
Date modified: 03/12/2013
Filesize: 202.6 kB

Vaishya, A., S. G. Jennings, and C. O Dowd (2012), Wind-driven influences on aerosol light scattering in north-east Atlantic air, Geophys. Res. Lett., 39 , L05805, doi:10.1029/ 2011GL050556.


 

Abstract. Ten years (20012010) of aerosol light-scattering measurements in N.E. Atlantic marine air are analysed to determine wind-speed related influences on scattering properties. The scattering coefficient and the backscattering coefficient dependency on wind speed (U) was determined for the winter (Low Biological Activity-LBA) and the summer seasons (High Biological Activity-HBA), and was found to be dependent on ~ U2. In spite of having a U2 dependency, scattering properties for the LBA-period are approximately twice those of the HBA-period. 96% of the LBA-HBA scattering difference can be explained by the combined effects of size distribution and refractive index differences while 70% of the scattering difference can be attributed to a difference in refractive index alone resulting from organic-matter enrichment during the HBA period. The 550 nm scattering coefficient was ~ 70 Mm-1 for ~ 25 ms-1 wind speeds, which is considerably higher than that encountered under polluted air masses in the same region. Indeed, Mulcahy et al. [2008] reported a high correlation between aerosol optical depth (AOD) and wind-speed with AOD values of 0.30.4 at moderately high wind speed. They found a power-law dependency between wind speed and AOD and suggested that sea spray contributed significantly to the direct radiative effect. O’Dowd et al. [1999] highlighted the preferential activation of sea salt nuclei over sulphate nuclei in marine clouds, while Ovadnevaite et al. [2011] found that even the water insoluble organic sea spray plumes have almost a 100% activation efficiency even at a low supersaturation of 0.2%, pointing to a significant role for sea spray in the direct radiative effect. While there have been many studies of aerosol lightscattering in remote locations and in marine air [Bodhaine, 1996; Parameswaran et al., 1998; Pereira et al., 2011], there have been few studies [e.g., Kleefeld et al., 2002] that have reported wind-dependent scattering dependency. The aim of present study is to establish a wind-speed scattering relationship for clean marine air masses for conditions representative of periods with high organic matter enrichment and periods with low organic matter enrichment.

 

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