Aged Volcanic Clouds

1. A52A-04 Aged Volcanic Clouds Are they an aviation hazard and why? Bill Rose, *Patricia Nadeau, Simon Carn Michigan Technological University David Schneider USGS Alaska Volcano Observatory

2. 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?

3. 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)

4. “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?

5. 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)

6. 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

7. 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

8. 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

9. GOES - visible Courtesy of Scott Bachmeier, U. Wisconsin, Madison

10. OMI - UV

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26. 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

27. Hekla – cloud chemistry • CIMS measured SO2/H2SO4 (gas) ~30,000 • However, although it wasn’t measured directly, there was probably abundant particulate H2SO4 in the cloud as well Rose, W. I., et al. (2006), J. Geophys. Res., 111, D20206

28. Hekla – cloud chemistry Beyond SO2 and H2SO4, cloud chemistry included many volcanogenic species that could potentially be hazardous to aircraft and passengers

29. Kasatochi cloud encounter A-Train views of the Kasatochi cloud on August 10 OMI SO2 - 21:35 UT CALIPSO Backscatter – 21:28 UT Solid particles at 11 km alt. CALIPSO V-cloud? Ice?

30. 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

31. Kasatochi cloud encounter A-Train views of the Kasatochi cloud on August 15 OMI SO2 - 11:55 UT CALIPSO 2:22 UT V-cloud Saharan dust CARIBIC flight (LH759) - 4:00-6:00 UT – 11.6 km alt. 1850 km CALIPSO

32. Hekla vs. Kasatochi Kasatochi cloud encounter in Europe (CARIBIC) found <2.6 - 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 ashand 0.1 to 0.25 ppbv of SO2 The much younger Hekla cloud had significantly higher values: 1-10 μg /m3 ashand 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)

33. Future considerations… What we know: What we don’t 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

34. 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