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Measurements of the aerosol size distributions in the El Chichon cloud
Author(s) -
Knollenberg Robert G.,
Huffman Dale
Publication year - 1983
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl010i011p01025
Subject(s) - aerosol , atmospheric sciences , altitude (triangle) , particle (ecology) , particle size distribution , environmental science , particle number , particle size , meteorology , geology , physics , nuclear physics , geometry , paleontology , oceanography , mathematics , plasma
Three particle size spectrometers were flown aboard the NASA‐U2 on numerous flights before and after the eruption of El Chichon to determine the effects of the eruption. Measurements of aerosol particles between 20° ‐ 50° north latitude over the North American continent show strong orders of magnitude enhancements in number and mass. Our analyses and supporting measurements by others, indicate that the aerosol between 0.1 ‐ 2.0 µ m is largely H 2 SO 4 while the aerosol larger than 2 µ m is likely ash. Comparisons of measurements using a spectrometer with an aerodynamically sensitive (particle size sorting) inlet with a second one that operated “in situ”, and a third one that operated isokinetically, indicate that the larger ash particles are of low bulk density. Observations of particles as large as 30 µ m four months after the eruption are only compatible with very low bulk densities. The H 2 SO 4 droplet populations show decreasing number density with altitude but increasing mass. The distribution is largely bimodal with 0.4 and 1.2 µ m modes typically observed. The mass is dominated by the 1.2 µ m mode.