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Science 20 February 1981:
Vol. 211. no. 4484, pp. 819 - 821
DOI: 10.1126/science.211.4484.819
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Articles

Trajectories of the Mount St. Helens Eruption Plume

EDWIN F. DANIELSEN 1

1 Theoretical and Planetary Studies, NASA Ames Research Center, Moffett Field, California 94035

The plume of the major eruption of Mount St. Helens on 18 May 1980 penetrated 10 to 11 kilometers into the stratosphere, attaining heights of 22 to 23 kilometers. Wind shears rapidly converted the plume from an expanding vertical cone to a thin, slightly inclined lamina. The lamina was extruded zonally in the stratosphere as the lower part moved eastward at jet stream velocities, while the upper part slowly moved westward in the region of nonsteady transition from the westerlies to the summer stratospheric easterlies. Trajectories computed to position the NASA U-2 aircraft for sampling in the plume are described. Plume volume after 8 hours of strong volcanic emission is estimated at 2 x 106 cubic kilometers. Only about 1 percent of this volume is attributed to the volcano; the rest was entrained from the environment.

Submitted on September 18, 1980
Revised on December 22, 1980


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Mercury Content of Equisetum Plants Around Mount St. Helens One Year After the Major Eruption.
B. Z. Siegel, B. Z. SIEGEL, and S. M. SIEGEL (1982)
Science 216, 292-293
   Abstract »    PDF »
Measurements of the Volcanic Plumes of Mount St. Helens in the Stratosphere and Troposphere: Introduction.
J. B. Pollack and J. B. POLLACK (1981)
Science 211, 815-816
   PDF »
Changes in Stratospheric Water Vapor Associated with the Mount St. Helens Eruption.
D. G. Murcray, D. G. MURCRAY, F. J. MURCRAY, D. B. BARKER, and H. J. MASTENBROOK (1981)
Science 211, 823-824
   Abstract »    PDF »
Measurements of Cloud Condensation Nuclei in the Stratosphere Around the Plume of Mount St. Helens.
C. F. Rogers, C. F. ROGERS, J. G. HUDSON, and W. C. KOCMOND (1981)
Science 211, 824-825
   Abstract »    PDF »
Filter Measurements of Stratospheric Sulfate and Chloride in the Eruption Plume of Mount St. Helens.
B. W. Gandrud, B. W. GANDRUD, and A. L. LAZRUS (1981)
Science 211, 826-827
   Abstract »    PDF »
Size Distributions and Mineralogy of Ash Particles in the Stratosphere from Eruptions of Mount St. Helens.
N. H. Farlow, N. H. FARLOW, V. R. OBERBECK, K. G. SNETSINGER, G. V. FERRY, G. POLKOWSKI, and D. M. HAYES (1981)
Science 211, 832-834
   Abstract »    PDF »


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