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Ice in volcanic clouds: where and when?. William I Rose, Michigan Technological University Houghton, MI USA www.geo.mtu.edu/volcanoes/vc_web/. 2 nd International Symposium on Volcanic Ash and Aviation Safety June 2004. What are volcanic clouds?. Clouds and precipitation analogy

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Ice in volcanic clouds where and when l.jpg

Ice in volcanic clouds: where and when?

William I Rose,

Michigan Technological University

Houghton, MI USA

www.geo.mtu.edu/volcanoes/vc_web/

2nd International Symposium on Volcanic Ash and Aviation Safety

June 2004


What are volcanic clouds l.jpg
What are volcanic clouds?

  • Clouds and precipitation analogy

  • After initial fallout of large (>1mm) particles, a volcanic cloud remains and it drifts about for days to months.

  • The volcanic cloud contains:

    Fine particles of ash, sulfate aerosol and hydrometeors

    Gaseous components, some volcanic and some the result of reactions with atmosphere


Examples of ice in volcanic clouds l.jpg
Examples of Ice in Volcanic Clouds

  • Ice Clearly Dominant:

    Rabaul 1994;

    Hekla 2000

  • Ice Clearly Subordinate:

    Spurr 1992;

    Augustine 1986;

    Cleveland, 2001;

    Kluchevskoi, 1994

  • Subequal ash and ice:

    Montserrat (Boxing Day, 1997)

    Pinatubo (15 June 1991)

    El Chichón (4 April 1982)

~250 KT fine ash

No ice detected


Slide4 l.jpg

Each of the pixels in the volcanic cloud can be replotted on a retrieval diagram, where its measured values can be compared with calculated values for spheres of various sizes with refractive indices equivalent to andesite. This give a rationale for mass determination of ash.

Wen & Rose, 1994, JGR 99: 5421-5431


Rabaul 19 sept 1994 l.jpg
Rabaul, 19 Sept 1994 a retrieval diagram, where its measured values can be compared with calculated values for spheres of various sizes with refractive indices equivalent to andesite. This give a rationale for mass determination of ash.

~2 MT ice, no fine ash detected

~80 KT SO2

Rose et al, 1995, Nature 375: 477-479.


Slide6 l.jpg

Rose a retrieval diagram, where its measured values can be compared with calculated values for spheres of various sizes with refractive indices equivalent to andesite. This give a rationale for mass determination of ash.et al, 1995, Nature 375: 477-479.


Slide7 l.jpg

Ice mass in cloud is >2MT a retrieval diagram, where its measured values can be compared with calculated values for spheres of various sizes with refractive indices equivalent to andesite. This give a rationale for mass determination of ash.

SO2 sequestered

Salty rainfalls in a wide arc N and NW

Sea salt in the tephra

Ice may reduce residence time of ash and SO2

Rose et al, 1995, Nature 375: 477-479.


Slide8 l.jpg

Source of H a retrieval diagram, where its measured values can be compared with calculated values for spheres of various sizes with refractive indices equivalent to andesite. This give a rationale for mass determination of ash.2O?

Sea water entered the active vent at Vulcan.

Vulcan

Shuttle radar image, NASA


Hekla 26 february 2000 l.jpg
Hekla, 26 February 2000 a retrieval diagram, where its measured values can be compared with calculated values for spheres of various sizes with refractive indices equivalent to andesite. This give a rationale for mass determination of ash.

  • Magma erupted: 0.11 km3

    = 3 x 105 Tg, mostly long after explosive phase

  • Ice in stratospheric cloud

    > 1 Tg

  • SO2 in stratospheric cloud ~100 kT (TOMS) 160-240 kT (MODIS)

  • Sulfate in stratospheric cloud 3-5 kT

  • Fine ash mass ~100 kT --only detected in first hour

  • Ice prominence due to large magmatic contribution?

Rose et al, 2003, AGU Geophys Monograph 139: 107-132.


Slide10 l.jpg

Total mass of fine particles in the Hekla volcanic cloud peaks at ~ 1 MT and decreases after 10 hours.

Rose et al, 2003, AGU Geophys Monograph 139: 107-132.


Cleveland 19 february 2001 l.jpg
Cleveland, 19 February 2001 peaks at ~ 1 MT and decreases after 10 hours.

  • Fine ash mass ~ 30 kT

  • SO2 release ~10 kT

  • Slight separation suggesting that SO2 was early and higher

  • Ice signal absent

  • SO4 mass ~2 kT

  • SO2 and ash interferences of interest


Slide12 l.jpg

Cleveland Volcano, Aleutian Is peaks at ~ 1 MT and decreases after 10 hours.

GOES-W 4-5 Brightness Temp Difference Image

D J Schneider

USGS/AVO


Slide13 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide14 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide15 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide16 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide17 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide18 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide19 l.jpg

D J Schneider peaks at ~ 1 MT and decreases after 10 hours.

USGS/AVO


Slide20 l.jpg

Spurr, 19 Aug 1992 peaks at ~ 1 MT and decreases after 10 hours.

~400 kT fine ash

~300 kT SO2

No ice detected

Transparent fringes and opaque core

 > 2

Rose et al, 2001, J Geol 109: 677-694


Atham eruption conditions axisymmetric mode l.jpg
ATHAM Eruption Conditions peaks at ~ 1 MT and decreases after 10 hours.Axisymmetric mode

  • Topography: Volcano width: 7.5 km. Elev 2.3 km, crater .7 km diam and .1 km depth

  • Temperature: Ambient 273K; magma 1273 K

  • Magmatic gasfraction: 3 wt %

  • Vent radius: 75 m; exit velocity: 250 m/s

  • Tracing ash: Coarse (90 microns); Fine (25 microns) ash modes with proportion 1:1

  • Atmospheric profile: Radiosonde data from Anchorage

  • Eruption rate: use average from observations, 1100 m3/s

C M Riley,2002, Ph D dissert, Michigan Tech Univ

C Textor et al, 2004, JGR in press


Slide22 l.jpg

ATHAM one hour old Spurr plume-- peaks at ~ 1 MT and decreases after 10 hours.

approximates observed height, width

ash

C M Riley,2002, Ph D dissert, Michigan Tech Univ

C Textor et al, 2004, JGR in press


Slide23 l.jpg

ATHAM one hour simulation-- peaks at ~ 1 MT and decreases after 10 hours.

Ice masses are <1% of ash

ice

C M Riley,2002, Ph D dissert, Michigan Tech Univ

C Textor et al, 2004, JGR in press


Soufri re hills 27 dec 1997 l.jpg
Soufriére Hills peaks at ~ 1 MT and decreases after 10 hours.27 Dec 1997

  • Slope failure and dome collapse

  • Pyroclastic surge and flow went into the sea, which caused a meteorological cloud

  • GOES 10 µm IR data shows the volcanic cloud growth well

Mayberry et al, 2003, Geol Soc London Mem 21: 539-555.


Soufri re hills 27 dec 199725 l.jpg
Soufriére Hills peaks at ~ 1 MT and decreases after 10 hours.27 Dec 1997

  • 2 Volcanic clouds about 12-15 km high resulted--one was ash rich (red-brown at left) and the other mainly ice (blue)

  • 15 km high, the two clouds overlap with distinguishable regions

  • Ash mass was ~45 kT; ice ~150 kT

Mayberry et al, 2003, Geol Soc London Mem 21: 539-555.


Pinatubo 15 june 1991 l.jpg
Pinatubo 15 June 1991 peaks at ~ 1 MT and decreases after 10 hours.

  • ~80 MT ice

  • ~50 MT fine ash

  • 18-19 MT SO2

  • ~3MT sulfate

  • Fallout of fine ash and ice was >90% in 3 days

  • SO2 was sequestered by ice

  • Subequal masses of ice and fine ash make detection quite difficult

Guo et al, 2004, G3, vol 5, no 5


Pinatubo 15 june 199127 l.jpg
Pinatubo 15 June 1991 peaks at ~ 1 MT and decreases after 10 hours.

  • Instead of plotting clearly in a field associated with ash or ice, Pinatubo volcanic cloud pixels mostly plot in a mixture region.

Guo et al, 2004, G3, vol 5, no 5


El chich n 4 april 1982 l.jpg
El Chichón 4 April 1982 peaks at ~ 1 MT and decreases after 10 hours.

  • ~7 MT fine ash

  • ~7 MT SO2

  • ~0.3 MT sulfate

  • Separation of ash and SO2 striking

  • Ice signal may obscure limits of E side of ash cloud

  • Fine ash fallout >90% in 3 days

Schneider et al, 1999, J Geophys Res 104: 4037-4050

Yu et al, 2000, AGU Geophys Monograph 116: 87-100


Slide29 l.jpg

Schneider et al, 1999, J Geophys Res 104: 4037-4050 peaks at ~ 1 MT and decreases after 10 hours.


Slide30 l.jpg

Schneider et al, 1999, J Geophys Res 104: 4037-4050 peaks at ~ 1 MT and decreases after 10 hours.


Slide31 l.jpg

Schneider et al, 1999, J Geophys Res 104: 4037-4050 peaks at ~ 1 MT and decreases after 10 hours.


Slide32 l.jpg

Ice dominant peaks at ~ 1 MT and decreases after 10 hours.

Schneider et al, 1999, J Geophys Res 104: 4037-4050


Conclusions l.jpg
Conclusions peaks at ~ 1 MT and decreases after 10 hours.

  • Ice is present in all cold volcanic clouds and this has important implications for hazards

  • Ice may be dominant, subordinate or subequal to ash in terms of mass

  • Sources of H2O include, magma, hydrosphere and hydrothermal systems

  • Ice enhances ash fallout and sequesters gases

  • Ice is quickly lost from stratospheric volcanic clouds


Slide34 l.jpg

Thanks to many colleagues, students and others who did the work on which this presentation is based!

Questions?

William I Rose,

Michigan Technological University

Houghton, MI USA

www.geo.mtu.edu/volcanoes/vc_web/



Slide38 l.jpg

Meteorological clouds contain “hydrometeors” which are particles of H2O--either liquid water or ice. Hydrometeors selectively absorb and scatter infrared radiation which is transmitted through the cloud from the earth below.


Slide39 l.jpg

High imaginary refractive index particles of H

Volcanic Clouds which contain silicate ash selectively absorb and scatter infrared radiation, in an opposite sense to the liquid water or ice particles in met clouds.


Slide40 l.jpg

Theoretical "net" of BTD and BT values, plotted on X-Y plot, forming a half ellipse. The individual pixel values from the volcanic cloud are plotted on the same plot in red.

Corners of the ellipse are marked by temperatures of the ocean and the volcanic cloud, where the atmosphere is opaque or perfectly transparent.


Soufri re hills 27 dec 199741 l.jpg
Soufriére Hills, 27 Dec 1997 forming a half ellipse. The individual pixel values from the volcanic cloud are plotted on the same plot in red.

  • Slope failure and dome collapse

  • Pyroclastic surge and flow went into the sea

  • 2 Volcanic clouds about 12-15 km high resulted--one was ash rich(red brown at left) and the other mainly ice (blue)

Mayberry et al, 2003, Geol Soc London Mem 21: 539-555.


Slide42 l.jpg

Transparent fringes and opaque core forming a half ellipse. The individual pixel values from the volcanic cloud are plotted on the same plot in red.