Aged Volcanic CloudsAged Volcanic Clouds

Are they an aviation hazard and why?

Bill Rose, *Patricia Nadeau, Simon CarnMichigan Technological University

David SchneiderUSGS Alaska Volcano Observatory

A52A-04

Aircraft HazardsAircraft 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?

Young volcanic cloud hazardsYoung 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)

“Aged” volcanic clouds“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?

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)

Kasatochi and OkmokKasatochi and Okmok

Kasatochi - October 23, 2008Image courtesy of Jerry Morris

New cone at Okmok – September 15, 2008Image courtesy of AVO/USGS (Photo by Christina Neal)

August 7, 2008

July 12, 2008

Aircraft encountersAircraft 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

Aircraft encountersAircraft 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

GOES - visibleGOES - visible

Courtesy of Scott Bachmeier, U. Wisconsin, MadisonCourtesy of Scott Bachmeier, U. Wisconsin, Madison

OMI - UVOMI - UV

Hekla – March, 2000Hekla – March, 2000

Chemical Ionization Mass Spectrometer

Forward Scattering Spectrometer Probe

Hygrometers

DACOM IR Laser Spectrometer

SOLVE (ozone study) campaign flight with array of atmospheric sampling instruments, including:

Hekla – cloud chemistryHekla – 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

Hekla – cloud chemistryHekla – cloud chemistry

Beyond SO2 and H2SO4, cloud chemistry included many volcanogenic species that could potentially

be hazardous to aircraft and passengers

Kasatochi cloud encounterKasatochi cloud encounter

A-Train views of the Kasatochi cloud on August 10

OMI SO2 - 21:35 UTCALIPSO Backscatter – 21:28 UT CALIPSO Backscatter – 21:28 UT

V-cloud? Ice?

Solid particles at 11 km alt.

CA

LIP

SO

Kasatochi cloud encounterKasatochi cloud encounter

Images courtesy of AVO/USGS. Images were taken on the Environmental Scanning Electron Microscope (ESEM) at the University of Alaska Fairbanks Advanced Instrumentation Laboratory

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.45 μm

50 μm

30 μm30 μm

40 μm

Kasatochi cloud encounterKasatochi cloud encounter

1850 km

CA

RIB

IC flight (LH

759) - 4:00-6:00 UT

– 11.6 km alt.

CA

RIB

IC flight (LH

759) - 4:00-6:00 UT

– 11.6 km alt.

OMI SO2 - 11:55 UT

A-Train views of the Kasatochi cloud on August 15C

AL

IPS

O

CALIPSO 2:22 UT

Saharan dust

V-cloud

Hekla vs. KasatochiHekla 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 UniversityProf. Bengt G. Martinsson Div. Nuclear Physics, Lund University)

These are equivalent to 0.005 to 0.1 μg/m3 ash and 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)

Future considerations…Future considerations…

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

More work like CARIBIC

What we don’t know:What we don’t know:What we know:What we know:

What are damage/danger thresholds for volcanic cloud constituents? (e.g., SO2 and sulfate)

Effect of exposure time?

Health risks for passengers on board?

Locations of SO2 clouds (OMI)

Cloud heights (CALIPSO)

Minor amounts of ash persist for days

Hekla plume components

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

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

Thank you