Aged Volcanic Clouds

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Aged Volcanic Clouds
A52A-04

• Are they an aviation hazard and why?

Bill Rose, Patricia Nadeau, Simon Carn Michigan
Technological University David Schneider USGS
Alaska Volcano Observatory
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Aircraft Hazards

• Volcanic clouds generally end up in the lower
  stratosphere
• Commercial aircraft fly at similar altitudes
  because of low turbulence, few clouds, jet stream
  winds
• Volcanic ash advisory centers (VAACs) have the
  task of advising pilots where hazardous volcanic
  clouds may be
• When are volcanic clouds no longer a threat to
  aircraft?

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Young volcanic cloud hazards

• Engine failure
• Sandblasting of windshield, compressor fan
  blades, etc.
• Blockage of fuel nozzles and cooling passages
• Etching of windshields
• British Airways Flight 9 to Perth Galunggung,
  1982
• KLM Flight 867 to Anchorage Redoubt, 1989
• 16 damaging encounters Pinatubo, 1991
• 100 encounters 1973-2000 (Guffanti, et al. 2004)

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Aged volcanic clouds

• Coarse ash falls out of cloud within 30 minutes
• Most remaining ash has fallen out of cloud within
  24-36 hours
• Trackable up to 4 days with IR split window,
  mostly SO2 and sulfate after that
• Aged over 2 days old
• Do they still pose a risk to aircraft?

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Volcanic clouds over western Montana on 7/18/2008
(photo by Margaret Patton, Research Office,
Montana Tech of The University of Montana)
Okmok July 12 plume seen from 28,000 ft over
Billings, Montana from the cockpit of a
commercial passenger flight on the evening of
7/19/2008. (Image courtesy of Bradley Johnson and
Alaska Airlines)
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Kasatochi and Okmok
July 12, 2008
August 7, 2008
New cone at Okmok September 15, 2008 Image
courtesy of AVO/USGS (Photo by Christina Neal)
Kasatochi - October 23, 2008 Image courtesy of
Jerry Morris
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Aircraft encounters

• Okmok
• 28 pilot reports July 18-20 over Northern US and
  parts of Canada
• Mentions of visible ash clouds, orange-tinted
  clouds, smells and throat irritation
• Kasatochi
• 38 pilot reports on/around August 10, Northern
  US and parts of Canada
• Mentions of visible ash, brown haze, rapid sky
  color changes, sulfur smell
• These are likely minimums for total encounters

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Aircraft encounters

• Kasatochi
• Major airline to Anchorage brief (few minutes)
  encounter near Whitehorse, Yukon Terr. No
  aircraft damage, but ash collected on various
  parts of plane
• Regional airline, B737 problems with
  pressurization over MacKenzie Valley of Northwest
  Terr. Following return to Yellowknife,
  grey-glittery coating in wheelwells, ash-type
  substance in out-flow valve
• Same aircraft 4 days later, loss of cabin
  pressure en route to Calgary. Re-routed to Fort
  McMurray, AB
• 4 encounters by CARIBIC (aboard Lufthansa
  flights) instruments over Europe Aug. 15 Sept.
  12

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GOES - visible
Courtesy of Scott Bachmeier, U. Wisconsin, Madison
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OMI - UV
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Hekla March, 2000
SOLVE (ozone study) campaign flight with array of
atmospheric sampling instruments, including
Chemical Ionization Mass Spectrometer Forward
Scattering Spectrometer Probe Hygrometers DACOM
IR Laser Spectrometer
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Hekla cloud particle content
North side ash and sulfate with little ice
South side ash and sulfate with abundant ice
Overall, similar to a sublimating stratospheric
cirrus cloud
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Hekla cloud chemistry

• CIMS measured SO2/H2SO4 (gas) 30,000
• However, although it wasnt measured directly,
  there was probably abundant particulate H2SO4 in
  the cloud as well

Rose, W. I., et al. (2006), J. Geophys. Res.,
111, D20206
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Hekla cloud chemistry
Beyond SO2 and H2SO4, cloud chemistry included
many volcanogenic species that could potentially
be hazardous to aircraft and passengers
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Kasatochi cloud encounter
A-Train views of the Kasatochi cloud on August 10
OMI SO2 - 2135 UT
CALIPSO Backscatter 2128 UT
Solid particles at 11 km alt.
CALIPSO
V-cloud? Ice?
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Kasatochi cloud encounter
Scanning electron photomicrographs of material
collected from the leading edge of the wing of a
commercial aircraft that encountered the
Kasatochi volcanic cloud at around 0100 UTC on
August 11, 2008 over the Yukon region.
30 µm
45 µm
50 µm
40 µm
Images courtesy of AVO/USGS. Images were taken on
the Environmental Scanning Electron Microscope
(ESEM) at the University of Alaska Fairbanks
Advanced Instrumentation Laboratory
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Kasatochi cloud encounter
A-Train views of the Kasatochi cloud on August 15
OMI SO2 - 1155 UT
CALIPSO 222 UT
V-cloud
Saharan dust
CARIBIC flight (LH759) - 400-600 UT 11.6 km
alt.
1850 km
CALIPSO
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Hekla vs. Kasatochi

• Kasatochi cloud encounter in Europe (CARIBIC)
  found lt2.6 - 17.8 ng/m3 of Si, equivalent to 15 -
  100 ng/m3 of ash and 243 - 399 ng/m3 of S,
  equivalent to 500 - 800 ng/m3 of SO2 (Prof.
  Bengt G. Martinsson Div. Nuclear Physics, Lund
  University)
• These are equivalent to 0.005 to 0.1 µg/m3 ash
  and 0.1 to 0.25 ppbv of SO2
• The much younger Hekla cloud had significantly
  higher values 1-10 µg /m3 ash and 1 ppmv
  SO2
• The differences are partly explained by the much
  greater age of the Kasatochi cloud (8 days vs.
  1.5 days for Hekla)

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Future considerations
What we know
What we dont know

• Locations of SO2 clouds (OMI)
• Cloud heights (CALIPSO)
• Minor amounts of ash persist for days
• Hekla plume components

• What are damage/danger thresholds for volcanic
  cloud constituents? (e.g., SO2 and sulfate)
• Effect of exposure time?
• Health risks for passengers on board?

• Need ground tests with companies like Boeing,
  etc. to establish limits on what is a threat to
  aircraft
• More work like CARIBIC

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Thank you
We would like to thank everyone who helped with
and contributed to this presentation, including
Bengt Martinsson and the CARIBIC project,
AVO/USGS, Kristi Wallace, Marianne Guffanti, the
SOLVE campaign, and Richard Honrath