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A model for tropical‐extratropical transport of volcanic ash in the lower stratosphere
Author(s) -
Rietmeijer Frans J. M.
Publication year - 1993
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 - 10.1029/93gl00735
Subject(s) - extratropical cyclone , stratosphere , tropopause , volcano , atmospheric sciences , northern hemisphere , altitude (triangle) , tropics , volcanic ash , geology , climatology , latitude , environmental science , geochemistry , geometry , mathematics , geodesy , fishery , biology
Large nonspherical volcanic ash particles up to 30 micrometer in size were collected between 17–19 km altitude over the northern hemisphere at high latitudes between October 1988 and April 1990. These particles may be derived from minor Plinian eruptions in the tropics rather than from localised volcanic activity close to the collection region. Ash particles were injected into the lower equatorial stratosphere where they entered a regime of efficient transport just above the tropopause from the tropical region towards the northern extratropical region. Transport is enhanced by stable autorotation that generates a sufficient lift force to loft nonspherical ash with a rough surface during transport, and by the gradually decreasing altitude of the tropopause from the tropics to the polar regions.