Stratospheric dust and its relationship to the meteoric influx

Abstract

A review of measurements sensitive to dust in the stratosphere is presented with special emphasis on the data obtained during the last 10 years. The measurements made by indirect techniques such as light scattering tend to show more stratospheric dust than the measurements obtained by direct sampling techniques, although this interpretation is somewhat complicated by the injection of dust from the Bali eruption in 1963, The discrepancy is interpreted as indicating that the stratospheric dust smaller than a few microns diameter is volital. Recent direct experimental evidence of the author supports this conclusion.The size distribution of stratospheric dust is presented as a composite of the results of several observers. A natural break in the distribution at a size of about 5/1 diameter is interpreted as indicating that the smaller dust is terrestrial in origin, while the larger dust is meteoric in origin. Other evidence is presented to support this conclusion. A comparison with particle flux measurements at 100 km and higher indicates that the meteoric component of the stratospheric dust is ablation products rather than single particles that have survived entry into the atmosphere. It is also argued that the small particles accounting for the high flux as measured by rocket and satellite microphone techniques are not present in the stratosphere.

Effects of meteoric debris on stratospheric aerosols and gases

“…According to Ferguson [1978], the positive ion mass spectra observed by Arnold et al [1977] between 35 and 45 km exhibit a mass sequence that may correspond to NaOHH+ ß (H20)n clusters. Utilizing this data, and employing ion chemistry rate coefficients measured for H2SO4 reactions by Viggiano et al [1980], •lrnold and Fabian [1980] deduced H2SO4 Direct observations of stratospheric aerosols also indicate a meteoric component [Rosen, 1969;Cadle. Unfortunately, Liu and Reid did not take into account sodium vapor removal on particles, and may have greatly overestimated the NaOH abundance (see below).…”

Nucleation processes and aerosol chemistry

“…Giant particles may reach sufficiently high temperature to melt as they enter and pass through the Earth's atmosphere. These give rise to the spherules collected by balloons in the upper atmosphere and also in some ground level samplings (see Rosen, 1969;Zacharav, 1962;and Kuiz, 1962). Particles that fall within the size category representing aerosols will have a relatively long residence time within the upper atmosphere and, these are undoubtedly responsible for some of the sporatic and transient aerosol layers reported by different observers.…”

“…Particles that fall within the size category representing aerosols will have a relatively long residence time within the upper atmosphere and, these are undoubtedly responsible for some of the sporatic and transient aerosol layers reported by different observers. Rosen (1969) estimates that only a few percent of the quasi-steady state Junge layer at 20 km is composed of particles which can be classified as spherules. Gadsden (1968) has shown that ablation occurs as meteors enter the Earth's atmosphere, and that this may give rise to the sodium and other metal ion layer at ,-~93 km.…”

“…It has been found that the relative particle concentrations vary with time, but not in a regular seasonal fashion (Reiter, 1971). Although the data are sparse and their accuracy uncertain, they do suggest that the particle sizes are made up of 3 distinct distributions: one representing particles less than 0.1 #m, another for sizes between 0.1 and 5/~m, and a third for particle sizes above 5/~m (Rosen, 1969). It has been implied that particles ~<0.I/~m in size may be of terrestrial origin, while particles with diameters greater than 5/~m may represent meteoritic material.…”

“…Recent reviews by Reiter (1971), Rosen (1969), and Cadle (1966), have given adequate, though sometimes conflicting, historical surveys of the early work and for this reason a detailed review will not be given here. In addition, * This research was performed under the auspices ofthe U.S. Atomic Energy Commission and partially financed by the Department of Transportation and the National Science Foundation under interagency agreements.…”