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Ash loading and insolation at Hanford, Washington during and after the eruption of Mount St. HelensThe effects of volcanic ash suspended in the atmosphere on the incident solar radiation was monitored at the Hanford Meteorological Station (HMS) subsequent to the major eruption of Mount St. Helens on May 18, 1980. Passage of the ash plume over Hanford resulted in a very dramatic decrease of solar radiation intensity to zero. A reduction in visibility to less than 1 km was observed, as great quantities of ash fell out of the plume onto the ground. Ash loading in the atmosphere remained very high for several days following the eruption, primarily as a result of resuspension from the surface. Visibilities remained low (2 to 8 km) during this period. Estimates of atmospheric turbidity were made from the ratio of diffuse-to-direct solar radiation; these turbidities were used to estimate extinction along a horizontal path, a quantity which can be related to visibility. Comparisons of observed and estimated visibilities were very good, in spite of the rather coarse approximations used in the estimates. Atmospheric clarity and visibility improved to near pre-eruption conditions following a period of rain showers. The diffuse-to-direct ratio of solar radiation provided a useful index for estimating volcanic ash loading of the atmosphere.
Document ID
Document Type
Conference Paper
Laulainen, N. S. (Battelle Pacific Northwest Labs. Richland, WA, United States)
Date Acquired
August 11, 2013
Publication Date
October 1, 1982
Publication Information
Publication: NASA. Langley Research Center Atmospheric Effects and Potential Climatic Impact of the 1980 Eruptions of Mt. St. Helens
Subject Category
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19830003264Analytic PrimaryAtmospheric Effects and Potential Climatic Impact of the 1980 Eruptions of Mount St. Helens
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