Analytical electron microscope studies of size-segregated particles collected during AGASP-II, flights 201?203

Sheridan, Patrick J.

doi:10.1007/bf00052837

Cited by 19 publications

(12 citation statements)

References 8 publications

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“…It would take ten hours to produce those particles, which was about the duration of sunshine on the Arctic airmass during the flights. If the humidity were to rise another few percentage points, the CN concentrations could easily approach 104-105 cm -3, the time to do so would be reduced, and the particles produced would be a few hundredths of a micron in size, comparable to sizes measured on these flights by Sheridan (1989) and on previous AGASP flights with a diffusion battery (Shaw, 1986). We see that binary homogeneous nucleation of the sulfuric acid -water system is quite capable of producing particles a few hundredths of a micron size and in concentrations of 104-105 cm -3 in a matter of a few hours.…”

Section: A~ ¢ A= = ~ (2)mentioning

confidence: 86%

“…As the haze aged, they observed that the particle size spectra shifted to larger (accumulation mode) aerosols. Sheridan (1989) and Chaun (1989) show that the small aerosol in the haze events on flights 201 and 202 were completely dominated by sub-micron H2SO 4 droplets in the region of the high CN concentrations.…”

Section: Haze Transportmentioning

confidence: 99%

“…Ash from eruptions occurring after 29 March was most likely transported across northern Canada and Greenland before entering the Arctic Basin, if it stayed aloft that long. Sheridan (1989) and Chaun (1989) studied the chemistry of single-aerosol particles collected during AGASP-II and observed the possible presence of volcanic materials in only one sample collected between Anchorage and Fairbanks.…”

Section: Introductionmentioning

confidence: 99%

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Meteorology and haze structure during AGASP-II, Part 1: Alaskan Arctic flights, 2?10 April 1986

et al. 1989

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The second Arctic Gas and Aerosol Sampling Program (AGASP-II) was conducted across the Alaskan and Canadian Arctic in April 1986, to study the in situ aerosol, and the chemical and optical properties of Arctic haze. The NOAA WP-3D aircraft, with special instrumentation added, made six flights during AGASP-II. Measurements of wind, pressure, temperature, ozone, water vapor, condensation nuclei (CN) concentration, and aerosol scattering extinction (b~,) were used to determine the location of significant haze layers. The measurements rhade on the ftrst three flights, over the Arctic Ocean north of Barrow and over the Beaufort Sea north of Barter Island, Alaska are discussed in detail in this report of the first phase of AGASP II. In the Alaskan Arctic the WP-3D detected a large and persistent region of haze between 960 and 750 mb, in a thermally stable layer, on 2, 8, and 9 April 1986. At its most dense, the haze contained CN concentrations >10,000 cm -3 and bsp of 80 × 10 -6 m -1 suggesting active SO2 to H2SO4 gas-to-particle conversion. Calculations based upon observed SO2 concentrations and ambient relative humidities suggest that 104-105 small H2SO4 droplets 18 G.A. HERBERT ET AL.could have been produced in the haze layers. High concentrations of sub-micron H2SO 4 droplets were collected in haze. Ozone concentrations were 5-10 ppb higher in the haze layers than in the surrounding troposphere.Outside the regions of haze, CN concentrations ranged from 100 to 400 cm -3 and bsp values were about (20-40) × 10 -6 m-1. Air mass trajectories were computed to depict the air flow upwind of regions in which haze was observed. In two cases the back trajectories and ground measurements suggested the source to be in central Europe.

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Section: A~ ¢ A= = ~ (2)mentioning

confidence: 86%

Section: Haze Transportmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Meteorology and haze structure during AGASP-II, Part 1: Alaskan Arctic flights, 2?10 April 1986

et al. 1989

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“…Winter Arctic air conditions were usually stable with litfie mixing of different air masses, and these processes could take place during transport to Barrow. Indeed, measurements from the first AGASP-1I flight on April 2-3, 1986, found SO 2 greater than 1 ppbv in a haze layer [Thornton et al, 1989] and I-I2SO a coated on solid particles, perhaps coal combustion products [Sheridan, 1989a], suggesting that sulfur in component C-1 was the result of SO 2 uptake by combustion-derived particles to form internal mixtures.…”

Section: Comyositions and Source Recognition Of Afrosol Componentsmentioning

confidence: 99%

Haze and other aerosol components in late winter Arctic Alaska, 1986

Shao-Meng¹,

Winchester²

1990

J. Geophys. Res.

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Three coarse and five fine aerosol components of different elemental compositions were identified at Barrow, Alaska, from March 17 to April 21, 1986, resolved by absolute principal component analyses of element concentrations in 280 sequential coarse and fine size fraction time step samples. In the coarse (> 2.5 μm), two components C‐1 and C‐2 had abundant Si, S, Cl, K, and Ca, but no Al, and together contained 85% of coarse S. Their compositions resembled expected products of carbonaceous fuel combustion, with Si being volatilized by carbon reduction and other metals volatilized perhaps as chloride salts. C‐1, with high trace metal contents, might be from nonferrous smelting, whereas C‐2, with high Fe, might be associated with conventional coal combustion. Both appeared semi‐aged with respect to acidic gas uptake because the S chemical equivalents were less than those of metals contributing to alkalinity. When combined with Cl, S was close to the metal equivalents, indicating complete acid‐base titration. A strong concentration rise of C‐1 and C‐2 occurred from March 25 to April 2 during a haze event, although C‐1 was also present at other times. Air trajectories showed that air masses arrived at Barrow during the haze event from eastern or northern Europe. The third component C‐3 was a dust aerosol rich in Al that contained high S but low Cl, suggesting saturation with H2SO4 and therefore aged and regional aerosols perhaps typical of the late winter Arctic. No major change in its concentration was observed to correspond to synoptic events. In the fine (< 2.5 μm), five components represent a sea‐salt aerosol, an S‐rich aerosol with some Si, K, Ca, and Fe, a trace metal aerosol, an Al‐rich dust, and a marine product with Br, S, and Cl. The sea‐salt was found only in three plumes when synoptic meteorology and air trajectories suggested origins in the North Pacific. The S‐rich aerosol, accounting for 73% of S and 40% of Si, was enhanced during the haze event by 75%, and existed over the entire period at rather high levels and might be due to SO2 oxidation and condensation on fine Si‐rich particles. The trace metal aerosol was always present and could have been generated from nonferrous smelters at lower latitudes. The Al‐rich dust particles contained 7% of S and were similar to component C‐3. The marine aerosol contained 74% of Br, 69% of Cl, and 20% of S, and could be from oxidation of marine biogenic Br and S gases. All but the sea‐salt were present at Barrow throughout the period, with no clear relation to air trajectories or synoptic meteorology. The results show that certain winter meteorological conditions favor pollutant transport from lower latitudes to the Arctic. But while haze is related to industrial pollutants, other nonpollution products are present in the winter Arctic and may be important constituents of haze. They also show that by careful data reduction and meteorological analysis, the sources and transport pathways of haze may be better understood.

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“…Errors in indicated radii are generally less than ±50%. (Gillette and Walker, 1977;Chylek et al, 1981;Pinnick et al, 1985;Sheridan and Musselman, 1985;Sheridan, 1989aSheridan, , 1989bSheridan et al, 1993;Reitmeijer and Janeczek, 1997). To predict the response of the probes to internal mixtures, we modify the response function (eq (1)) by choosing the simplest possible model: that of a sphere containing a spherical inclusion (Ngo et al, 1996).…”

Section: Response Predictions For Homogeneous Particlesmentioning

confidence: 99%

Response Characteristics of Active Scattering Aerosol Spectrometer Probes Made by Particle Measuring Systems

Pinnick¹,

Pendleton²,

Videen³

2000

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Predictions are reported of the size response of various light-scattering aerosol counters manufactured by Particle Measuring Systems. Models considered are those that exploit the high intensity of light available within the cavity of a HeNe gas laser (generically referred to by the manufacturer as "active scattering aerosol spectrometer probes"). The new response function properly averages over particle trajectories through nodes, antinodes, and intermediate regions of the intracavity laser beam. Our studies address probes having two basic scattering geometries: those that collect light scattered over a relatively narrow solid angle (subtending angles between 4° and 22° from the laser beam axis) and those that collect light over a rather large solid angle (between 35° and 120°). The new response function predicts smoother dependence on particle size than the previous response function of Pinnick and Auvermann (1979, J. Aerosol Sei. 10: 55-74) and is in better agreement with measurement. Response calculations for common atmospheric aerosol (water, sulfuric acid, ammonium sulfate, and black carbon) reveal the considerable sensitivity of the response to particle dielectric properties. Comparison of response calculations with the manufacturer's calibration reveals conditions for which the manufacturer's calibration is most appropriate, and the potential for errors (as much as a factor of two in sizing) when it is blindly applied. These results should help the user of these instruments to more realistically interpret size distribution measurements.

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Analytical electron microscope studies of size-segregated particles collected during AGASP-II, flights 201?203

Cited by 19 publications

References 8 publications

Meteorology and haze structure during AGASP-II, Part 1: Alaskan Arctic flights, 2?10 April 1986

Meteorology and haze structure during AGASP-II, Part 1: Alaskan Arctic flights, 2?10 April 1986

Haze and other aerosol components in late winter Arctic Alaska, 1986

Response Characteristics of Active Scattering Aerosol Spectrometer Probes Made by Particle Measuring Systems

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