A study of stratospheric aerosol maturity

Abstract

In this paper we describe a sampling and analysis technique that uses the binomial distribution to characterize stratospheric aerosol populations at the 95% level of confidence. Particle samples obtained over Alaska during July 15‐19, 1979, are used; the results show the presence of more small particles at lower altitude than at high altitudes. We also give calculations of the surface area and volume distributions for all aerosol samples collected. Evidence from these data suggests either that Aitken nuclei are injected or diffused across the tropopause and rise into the stratosphere, where they mature into larger particles, or nuclei form in the lower stratosphere and become mature aerosols at high altitude. Samples obtained at another site give the same results, supporting the view that the process of injection or nucleation and maturing of aerosols with altitude may be global and need not occur only in locations exhibiting unique meteorologic features.

Latitudinal and altitudinal variation of size distribution of stratospheric aerosols inferred from Sage aerosol extinction coefficient measurements at two wavelengths

“…It is found that a larger number of small particles are concentrated in the lower stratosphere in the tropical region, and these small particles grow to larger particles as they move upward in this region. Our results support the view that aerosols grow as they rise through the stratosphere as predicted by the modeling results of Turco et al [1979] and Toon et al [1979], and concluded by different experimentalists [Bigg, 1976;Farlow et al, 1979;Oberbeck et al, 1981], and by the SAGE extinction ratio values at 1/am versus latitude [McCormick, 1983]. As these particles move toward higher latitudes in both hemispheres, with some subsiding in mid-latitudes, they grow larger.…”

Evolution of Pinatubo aerosol near 19 km altitude over western North America

“…Sampling and sizing errors are reflected through error bars on the graphs (Figure 1). Details of the statistical methods used to obtain these error bars are given by Oberbeck et al [1981]. Impactorderived sulfate masses are estimates, as errors in them average _+26% [Snetsinger et al, 1987[Snetsinger et al, , 1992.…”

Calibration Correction of an Active Scattering Spectrometer Probe to Account for Refractive Index of Stratospheric Aerosols: Comparison of Results with Inertial Impaction

“…The voltage boundaries on the multichannel analyzer were not reset in this recalibration; rather, new particle sizes were assigned to existing voltage levels. Most of the new size intervals include more than one of the PMS channels which were grouped for convenience in data handling and to avoid the possibility of multivalued response (Pinnick and Auvermann, 1979). The centers of the triangular symbols in Figure 1 indicate the channel boundaries used in this analysis for the sulfuric acidwater solution particles found in the stratosphere.…”

“…The size is then plotted versus concentration to generate a size frequency spectrum, a typical example of which is shown by the points labeled a in Figures 3 and 4. The vertical error bars in the size distribution are 95% confidence intervals of a binomial distribution (Oberbeck et al, 1981;Oberbeck, 1989). Uncertainties in the droplet height measurements are indicated by horizontal error bars; we use the distribution method (Snedecor and Cochran, 1967) for sample means to obtain 95% confidence intervals for each spherical particle radius.…”

“…We routinely collect stratospheric aerosols by impingement on wires and/or disks that are extended beyond the skin layer of U-2 and ER-2 research aircraft (Farlow et al, 1973;Oberbeck et al, 1981;Oberbeck, 1989). Initially, the collection device consisted of 75-pm palladium wires to assure high collection efficiency for submicron particles.…”