Collection of microparticles at high balloon altitudes in the stratosphere

Abstract

We report the collection of stratospheric particles at 34-36 km using balloon-borne collectors. The concentration of particles on the collection surfaces and element concentrations were measured on the majority of the particles using scanning electron microscope (SEM) and proton-induced X-ray emission (PIXE) analysis respectively. Particle morphologies, elemental composition, and electron diffraction data were obtained on a small number of the collected particles using transmission electron microscope (TEM) techniques. The concentration of particles between 0.045 (lower imaging limit) and 1/tin in radius is several orders of magnitude above the blank levels on the collection surfaces while the concentration of particles above 1 #m is near blank levels. More than 106 submicron particles were collected. The concentration of submicron particles is between 10 and 50 times the concentration expected at the sampling altitude based on models using the measured flux of extraterrestrial particles to the atmosphere. The higher concentration of submicron particles may be due to contributions from volcanic particles, inaccuracies in the influx of particles of this size to the earth, or breakup of larger particles. Analysis of the elemental composition using PIXE showed C1, S, Ti, Fe, Br, Ni, Zr, Zn, Sr, and Cu in decreasing order of concentration. Elements below S could not be detected in the analysis. C1, S, and Br are believed to be present due to reaction of the collection surfaces and particles with atmospheric gases while the other elements are present in the particles. The elemental composition of the particles does not aUow an unequivocal origin to be assigned because particles from several of the possible sources listed above contain the measured elements. TEM analysis of 23 of the submicron particles showed 16 to be non-graphitic. The particles ranged from A1 rich silicates to almost pure Fe to one containing almost exclusively Ba and S. None were definitely chondritic in composition. This collection of particles complements existing collections obtained by aircraft. They were collected at much higher altitude and are predominantly submicron in size. Collection and analysis of particles at high altitudes using balloons presents unique challenges and opportunities in understanding the particle population in the stratosphere.

Technical Note: A novel rocket-based in situ collection technique for mesospheric and stratospheric aerosol particles

“…TEM grids were previously used in aerosol collection experiments on stratospheric balloons (e.g. Bigg et al, 1971;Testa et al, 1990;Corte et al, 2012) and sounding rockets (Gumbel, 2007). The sticking probability for nanometre particles accelerated to 1 km s −1 on TEM grids was tested by Reissaus et al (2006).…”

Sub-micrometer refractory carbonaceous particles in the polar stratosphere

“…Carbonaceous particles (diameter ∼ 0.1 µm) which might be soot although they were not unequivocally identified as such, due to the lack of high-resolution images, were found by Chuan and Woods (1984). Testa et al (1990) found seven poorly graphitized carbon particles in their samples and regarded them as artifacts of carbon films from the TEM grids. As they did not provide images of these particles, they cannot be compared to our findings.…”

“…There are, however, several previous publications which describe the presence of a variety of other refractory particle groups in addition to carbonaceous particles. These additional particle groups include metallic particles (Chuan and Woods, 1984;Sheridan et al, 1994;Chen et al, 1998;Baumgardner et al, 2004;Ebert et al, 2016), meteoritic particles (Murphy et al, 1998(Murphy et al, , 2007Renard et al, 2008, silicates (Testa et al, 1990;Ebert et al, 2016), crustal-type particles (Sheridan et al, 1994;Chen et al, 1998), and Ca-bearing particles (Della Corte et al, 2013;Ebert et al, 2016).…”

Stratospheric Solid Particles Collected at 24 km Altitude over Japan Using a Balloon-Borne Impactor

“…Probably, the composition and concentration of stratospheric solid particles vary greatly with time, location, and/or altitude. It should be noted that Testa et al (1990) also reported the deficiency of Al-rich grains for the sample collected at 34-36 km altitude in 1984. 4.3 Cr + Fe + Ni particles transported from the surf ace We have found 14 particles composed of Cr, Fe and Ni in the present sample.…”

“…Collection of solid (i.e., water insoluble) particles m the stratosphere has been carried out by many researchers (Mossop, 1964;Brownlee et al, 1976;Gooding et al, 1983;Zolensky and Mackinnon, 1985;Zolensky et al, 1989;Testa et al, 1990). These collections have revealed the existence of a remarkable variety of material: (1) volcanic ash, (2) soils and products of rock weathering, (3) rocket exhaust and rocket/satellite debris, and (4) interplanetary dust falling to Earth from space and ablation debris of meteorites (cf.…”