Abstract

The NASA/Ames Research C-141 aircraft underflew the Mount St. Helens ejecta plume in Utah three days after the eruption. Upward-looking 20–40-μm on-board radiometry provided data resulting in a calculated long-wave transmission of 0.93. From this value, an optical depth of 0.073 is inferred. This value is compared with an accepted background, stratospheric infrared optical depth of 0.06. Assumptions on particle size, shortwave albedo, and thermal warming imply little surface temperature change caused by the ejecta on the third day immediately following the eruption.

© 1981 Optical Society of America

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References

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  1. P. A. Davis, “Applications of an airborne ruby lidar during a BOMEX program of cirrus observations,” J. Appl. Meteorol. 10, 1314 (1971).
    [CrossRef]
  2. P. M. Kuhn, “Airborne observations of contrail effects on the thermal radiation budget,” J. Atmos. Sci. 27, 937 (1970).
    [CrossRef]
  3. Scientific Event Alert Network Bulletin, Smithsonian Institution, Washington, D.C., May31, 1980.
  4. J. E. Hansen, W. C. Wang, A. A. Lacis, “Mount Agung eruption provides test of a global climatic perturbation,” Science 199(3), 1065 (1978).
    [CrossRef] [PubMed]
  5. O. B. Toon, J. B. Pollack, “Atmospheric aerosols and climate,” Am. Sci. 68(3), 268 (1980).
  6. J. E. Hansen, W. C. Wang, A. A. Lacis, “Climatic effects of atmospheric aerosols,” in Proceedings of Conference on Aerosols: Urban and Rural Characteristics, Source and Transport Studies (New York Academy of Science, New York, 1979).

1980 (1)

O. B. Toon, J. B. Pollack, “Atmospheric aerosols and climate,” Am. Sci. 68(3), 268 (1980).

1978 (1)

J. E. Hansen, W. C. Wang, A. A. Lacis, “Mount Agung eruption provides test of a global climatic perturbation,” Science 199(3), 1065 (1978).
[CrossRef] [PubMed]

1971 (1)

P. A. Davis, “Applications of an airborne ruby lidar during a BOMEX program of cirrus observations,” J. Appl. Meteorol. 10, 1314 (1971).
[CrossRef]

1970 (1)

P. M. Kuhn, “Airborne observations of contrail effects on the thermal radiation budget,” J. Atmos. Sci. 27, 937 (1970).
[CrossRef]

Davis, P. A.

P. A. Davis, “Applications of an airborne ruby lidar during a BOMEX program of cirrus observations,” J. Appl. Meteorol. 10, 1314 (1971).
[CrossRef]

Hansen, J. E.

J. E. Hansen, W. C. Wang, A. A. Lacis, “Mount Agung eruption provides test of a global climatic perturbation,” Science 199(3), 1065 (1978).
[CrossRef] [PubMed]

J. E. Hansen, W. C. Wang, A. A. Lacis, “Climatic effects of atmospheric aerosols,” in Proceedings of Conference on Aerosols: Urban and Rural Characteristics, Source and Transport Studies (New York Academy of Science, New York, 1979).

Kuhn, P. M.

P. M. Kuhn, “Airborne observations of contrail effects on the thermal radiation budget,” J. Atmos. Sci. 27, 937 (1970).
[CrossRef]

Lacis, A. A.

J. E. Hansen, W. C. Wang, A. A. Lacis, “Mount Agung eruption provides test of a global climatic perturbation,” Science 199(3), 1065 (1978).
[CrossRef] [PubMed]

J. E. Hansen, W. C. Wang, A. A. Lacis, “Climatic effects of atmospheric aerosols,” in Proceedings of Conference on Aerosols: Urban and Rural Characteristics, Source and Transport Studies (New York Academy of Science, New York, 1979).

Pollack, J. B.

O. B. Toon, J. B. Pollack, “Atmospheric aerosols and climate,” Am. Sci. 68(3), 268 (1980).

Toon, O. B.

O. B. Toon, J. B. Pollack, “Atmospheric aerosols and climate,” Am. Sci. 68(3), 268 (1980).

Wang, W. C.

J. E. Hansen, W. C. Wang, A. A. Lacis, “Mount Agung eruption provides test of a global climatic perturbation,” Science 199(3), 1065 (1978).
[CrossRef] [PubMed]

J. E. Hansen, W. C. Wang, A. A. Lacis, “Climatic effects of atmospheric aerosols,” in Proceedings of Conference on Aerosols: Urban and Rural Characteristics, Source and Transport Studies (New York Academy of Science, New York, 1979).

Am. Sci. (1)

O. B. Toon, J. B. Pollack, “Atmospheric aerosols and climate,” Am. Sci. 68(3), 268 (1980).

J. Appl. Meteorol. (1)

P. A. Davis, “Applications of an airborne ruby lidar during a BOMEX program of cirrus observations,” J. Appl. Meteorol. 10, 1314 (1971).
[CrossRef]

J. Atmos. Sci. (1)

P. M. Kuhn, “Airborne observations of contrail effects on the thermal radiation budget,” J. Atmos. Sci. 27, 937 (1970).
[CrossRef]

Science (1)

J. E. Hansen, W. C. Wang, A. A. Lacis, “Mount Agung eruption provides test of a global climatic perturbation,” Science 199(3), 1065 (1978).
[CrossRef] [PubMed]

Other (2)

Scientific Event Alert Network Bulletin, Smithsonian Institution, Washington, D.C., May31, 1980.

J. E. Hansen, W. C. Wang, A. A. Lacis, “Climatic effects of atmospheric aerosols,” in Proceedings of Conference on Aerosols: Urban and Rural Characteristics, Source and Transport Studies (New York Academy of Science, New York, 1979).

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Figures (3)

Fig. 1
Fig. 1

Real-time, on-board computer-plotted C-141 flight track under Mount St. Helens ejecta plume. Wind barbs fly with the winds. Tic-mark triangles point in direction of flight. Initial track start time is 00:16:56. Dashed line is west boundary of plume.

Fig. 2
Fig. 2

Vertical components of upward, downward, and cloud radiance through, against, and from volcano plume. N represents radiance, σ is reflectivity, τ is transmissivity, and c refers to the plume.

Fig. 3
Fig. 3

Real-time, on-board computer-plotted infrared radiance observed versus time and altitude.

Tables (1)

Tables Icon

Table 1 C-141-A Aircraft Radiometer Specifications

Equations (3)

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N ( W cm 2 sr 1 ) = τ Δ υ N 2 + ( 1 τ Δ υ ) N c + ρ Δ υ ( N 2 N c ) .
τ Δ υ = N N c N 2 N c ρ Δ υ ( N 2 N c ) N 2 N c .
τ Δ υ = e κ Δ υ d z

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