Vol. 23 No. 3 (1984)
Articles

TEMPORAL VARIATIONS IN CHARACTERISTICS OF THE EL CHICHON STRATOSPHERIC CLOUD

R. L. CHUAN
Bio
D. C. WOODS
Bio

Published 1984-07-01

How to Cite

CHUAN, R. L., & WOODS, D. C. (1984). TEMPORAL VARIATIONS IN CHARACTERISTICS OF THE EL CHICHON STRATOSPHERIC CLOUD. Geofísica Internacional, 23(3), 335-349. https://doi.org/10.22201/igeof.00167169p.1984.23.3.1155

Abstract

In situ measurements and sampling of the El Chichón eruption cloud, at 18 - 21 km altitude, were conducted over an extended period from April to December 1982, to examine the physical and chemical characteristics of the aerosol particles, their size distribution, mass concentration, morphology, and elemental composition. Within the first month after the eruption, the aerosol size distribution was dominated by solid magmatic and lithic particles, between about 3 µm and 20 µm aerodynamic diameter. In early May 1982 (1 month after the eruption), the size distribution was trimodal, with significant fractions of the mass in both the mid-size (0.5 to 3 µm) and the large-size (> 3 µm) bands. At the upper end of the mid-size band (about 1 to 3 µm), the particles were solid but mantled in sulfuric acid, while the lower end of the band was almost totally populated by sulfuric acid droplets about 0.5 to 1.0 µm diameter. The small-size band (<0.5 µm) consisted of very fine acid droplets. There were additional features appearing at various times which are unusual for eruption aerosols. Among them are samples collected in April and May which had a nearly monodisperse band (about 1 µm to 3 µm), consisting of halite particles, which are believed to have been formed by the condensation of vapors from a salt dome under El Chichón. In late July 1982, copper-zinc oxide particles, possibly formed by oxidation of vapors volatized from the magma during eruption, were abundant in sizes ranging from > 20 µm to submicron sizes. Between July and December 1982, the <0.2 µm size band was dominated by clusters of carbonaceous particles, probably not related to the eruption but possibly of meteoritic origin.