Sulfur in particles in Arctic hazes derived from airborne in situ and lidar measurements

Brock, C. A.; Radke, Lawrence F.

doi:10.1029/jd095id13p22369

Cited by 33 publications

(25 citation statements)

References 68 publications

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“…Mean cluster values based on the HCA results are listed in Table 10. These mean cluster values are comparable to values reported in other studies (Kahn, 1981;Radke et al, 1984;Ottar et al, 1986;Brock et al, 1990;Khattatov et al, 1997;Nagel et al, 1998). For example, Clarke et al (1984) determined the mean scattering coefficient and absorption coefficient (at 550 nm) for haze layers of around 0.016 km −1 and 0.0026 km −1 , respectively.…”

Section: Vertical Time-series During Astarsupporting

confidence: 74%

Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area

Treffeisen

Herber

Ström

et al. 2004

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T Atmospheric aerosols play an important role in global climate change, directly through radiative forcing and indirectly through their effect on cloud properties. Numerous measurements have been performed in the last three decades in order to characterize polar aerosols. Information about aerosol characteristics is needed to calculate induced changes in the Earth's heat balance. However, this forcing is highly variable in space and time. Accurate quantification of forcing by aerosols will require combined efforts, assimilating information from different sources such as satellite, aircraft and surface-based observations. Adding to the complexity of the problem is that the measurements themselves are often not directly comparable as they vary in spatial/temporal resolution and in the basic properties of the aerosol that they measure. Therefore it is desirable to close the gap between the differences in temporal and spatial resolution and coverage among the observational approaches. In order to keep the entire information content and to treat aerosol variability in a consistent and manageable way an approach has to be achieved which enables one to combine these data. This study presents one possibility for linking together a complex Arctic aerosol data set in terms of parameters, timescale and place of measurement as well as meteorological parameters. A cluster analysis was applied as a pattern recognition technique. The data set is classified in clusters and expressed in terms of mean statistical values, which represent the entire database and its variation. For this study, different time-series of microphysical, optical and chemical aerosol parameters as well as meteorological parameters were analysed. The database was obtained during an extensive aerosol measurement campaign, the ASTAR 2000 (Arctic Study of Tropospheric Aerosol and Radiation) field campaign, with coordinated simultaneous ground-based and airborne measurements in the vicinity of Spitsbergen (Svalbard). Furthermore, longterm measurements at two ground-based sites situated at different altitudes were incorporated into the analysis. The approach presented in this study allows the necessary linking of routine long-term measurements with short-term extensive observations. It also involves integration of intermittent vertical aerosol profile measurements. This is useful for many applications, especially in climate research where the required data coverage is large.

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Section: Vertical Time-series During Astarsupporting

confidence: 74%

Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area

Treffeisen

Herber

Ström

et al. 2004

Tellus B: Chemical and Physical Meteorology

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“…The dual wavelength lidar, used for measurements of optical backscatter, has only been qualitatively evaluated. The procedure for this is described by Brock et al [ 1990].…”

Section: Remote Sensingmentioning

confidence: 99%

Airborne measurements of particle and gas emissions from the 1990 volcanic eruptions of Mount Redoubt

Hobbs¹,

Radke²,

Lyons³

et al. 1991

J. Geophys. Res.

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174

121

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Airborne in situ and remote sensing (lidar and correlation spectrometer) measurements are described for the volcanic emissions from Mount Redoubt, Alaska, in January and June 1990. The lidar provided excellent real-time information on the distribution of the volcanic effluents. In postanalysis the lidar observations were used to determine cross-sectional areas of the plumes of emissions which, together with the airborne in situ measurements, were used to derive the fluxes of particles and gases from the volcano. For the intraeruptive emissions the ranges of the derived fluxes were for water vapor, ~160-9440 kg s-l; for CO2, ~30-1710 kg s-l; for SO2, ~1-140 kg s-l; for particles (<48 gm diameter), ~1-6 kg s-l; for SO•, <0.1-2 kg s-l; for HC1, <0.01-2 kg s-l; and for NOx, <0.•1-2 kg s -1. Independent measurements of SO2 from a correlation spectrometer during the period of active dome growth between late March and early June 1990 gave fluxes from 12 to 75 kg s -1. The particles in the intraeruptive emissions consisted primarily of silicate rock and mineral fragments devoid of any sulfuric acid coating. Very little of the SO2 (~0.1%) was oxidized to sulfate in the cold, dark conditions of the Arctic atmosphere. During a large eruption of Mount Redoubt on January 8, 1990, the particle (<48 gm diameter) emission flux averaged ~104 kg s -1. During posteruptive emissions on June 11, 1990, the fluxes of both particles and gases were either close to or less than our lower detection limits (except for water vapor, which had a flux of ~6 x 103 kg s-l). Introduction On December 14, 1989, after 21 years of quiescence the Redoubt Volcano, located 180 km southwest of Anchorage, Alaska, erupted violently, sending an ash cloud to a peak altitude of over 12 km. This eruption was the seventh eruptive sequence since Captain James Cook named the volcano in 1798. On December 15, 1989, the four turbofan engines of a new Boeing 747-400 aircraft stalled when it encountered the ash cloud while descending for a landing at Anchorage. The aircraft fell for about 8 min, losing more than 3 km of altitude, before the crew restarted two of the engines. Subsequently, the other two engines were started, and the aircraft landed safely. However, $80 million of damage was done to the nearly new aircraft. On the same day, two other aircraft were damaged by encounters with the ash cloud. During the next month or so, air traffic in Alaska, our research group deployed its Convair C-!31A research aircraft to Anchorage on January 3, 1990, for the purpose of studying the emissions from Redoubt. This airborne research facility has been used to study the emissions from many volcanoes, including Mount Baker, Washington [Radke et al., 1976], St. Augustine, Alaska [Hobbs et al., 1977], Mount Mageik and Mount Martin [Stith et al., 1978], and Mount St. Helens [Hobbs et al., 1981, 1982]. Descriptions of the instrumentation and techniques that we use for obtaining airborne in situ measurements of volcanic emissions may be found in these papers. The principal goals of...

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“…Many studies have been carried out to improve our current understanding on climate processes related to short lived climate forcers in the Arctic atmosphere , while most of the previous work was based on surface observations (Sirois and Barrie, 1999;Ricard et al, 2002;Quinn et al, 2002Quinn et al, , 2008. Few airborne campaigns have been performed to date (Shaw, 1975;Schnell, 1984;Brock et al, 1990;Browell et al, 1992;Dreiling and Friederich, 1997). Furthermore, many advances in measurement techniques, especially for aerosol measurements (aerosol mass spectrometry, aerosol light absorption, aerosol volume volatility), have been achieved recently (Bond et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Physical and chemical properties of pollution aerosol particles transported from North America to Greenland as measured during the POLARCAT summer campaign

et al. 2011

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Abstract. Within the framework of the POLARCAT-France campaign, aerosol physical, chemical and optical properties over Greenland were measured onboard the French ATR-42 research aircraft. The origins of CO excess peaks detected in the aircraft measurements then have been identified through FLEXPART simulations. The study presented here focuses particularly on the characterization of air masses transported from the North American continent to Greenland. Air masses that picked up emissions from Canadian boreal forest fires as well as from the cities on the American east coast were identified and selected for a detailed study. Measurements of CO concentrations, aerosol chemical composition, aerosol number size distributions, aerosol volume volatile fractions and aerosol light absorption (mainly from black carbon) are used in order to study the relationship between CO enhancement ( CO), aerosol particle concentrations and number size distributions. Aerosol number size distributions (normalised with their respective CO) are in good agreement with previous studies. Nonetheless, wet scavenging may have occurred along the pathway between the emission sources and Greenland leading to a less pronounced accumulation mode in the POLARCAT data. Chemical analyses from mass spectrometry show that submicrometer aerosol particles are mainly composed of sulphate and organics. The observed bimodal (Aitken and accumulation) aerosol number size distributions show a significant enhancement in Aitken mode particles. Furthermore, results from the thermodenuder analCorrespondence to: B. Quennehen (b.quennehen@opgc.univ-bpclermont.fr) ysis demonstrate the external mixture of boreal fire (BF) air masses from North America (NA). This is particularly observed in the accumulation mode, containing a volume fraction of up to 25-30 % of refractory material at the applied temperature of 280 • C. NA anthropogenic air masses with only 6 % refractory material in the accumulation mode can be clearly distinguished from BF air masses. Overall, during the campaign rather small amounts of black carbon from the North American continent were transported towards Greenland during the summer POLARCAT observation period, which also is a valuable finding with respect to potential climate impacts of black carbon in the Arctic.

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Sulfur in particles in Arctic hazes derived from airborne in situ and lidar measurements

Cited by 33 publications

References 68 publications

Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area

Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area

Airborne measurements of particle and gas emissions from the 1990 volcanic eruptions of Mount Redoubt

Physical and chemical properties of pollution aerosol particles transported from North America to Greenland as measured during the POLARCAT summer campaign

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