Comparison of stratospheric aerosol measurements over Poker Flat, Alaska, July, 1979

Abstract

Stratospheric aerosols were collected at Poker Flat, Alaska, in July, 1979, to determine particle properties, confirm coincident satellite SAGE measurements, and compare similar results obtained with different airborne samplers. Because of the steep slopes in size‐distribution curves for larger particles, we found properties such as concentration, aerosol mass, and optical extinction are very sensitive to small errors in radii. We calculate that our concentration measurements agree with photoelectric particle counter results when a 16% radius change is introduced. An 8% radius change matches our calculated sulfate mass with filter mass measurements. And a 13% radius change results in agreement between our calculated optical extinction and coincident SAGE satellite results. Recognizing that different instruments can produce 10‐20% differences in measured sizes, we believe the results of these comparative measurements of SAGE and in situ instruments are essentially in agreement.

A study of stratospheric aerosol maturity

“…Basic size-frequency distributions with 95% confidence intervals are presented in the companion paper in this series [Farlow et al, 1981]. The product of these interval limits and the total particles collected gives the 95% confidence intervals for the number of particles of radius R in the volume of air sampled.…”

“…These values are multiplied by surface area or volume to obtain corresponding confidence intervals for these distributions. Basic size-frequency distributions with 95% confidence intervals are presented in the companion paper in this series [Farlow et al, 1981].…”

“…For other studies involving these collections, see the companion paper [Farlow et al, 1981] included in this series of articles. A major objective of the study was to use this sampling opportunity to further our understanding of the evolution of the aerosol layer from an examination of aerosol concentration, surface area, and volume distributions.…”

“…Evidence is given for aerosol particles not much larger than Aitken nuclei at or near the tropopause; the aerosols mature progressively at higher altitudes as indicated by an increase in radii of modes in the surface area and volume distributions with altitude. For other studies involving these collections, see the companion paper [Farlow et al, 1981] included in this series of articles.…”

Effects of El Chichón on stratospheric aerosols late 1982 to early 1984

“…For a number of years we have been routinely monitoring stratospheric aerosols, not only when they have been at background level [Farlow et al, , 1981a, but also during the more recent volcanic perturbations produced by Mount St. Helens [Farlow et al, 1981b;Oberbeck et al, 1982], the Alaid eruption, and especially, E1 Chich6n. A previous paper [Oberbeck et al, 1983] describes aerosol effects from E1 Chich6n's main eruption (April 4, 1982) to December 1982.…”