# Presentation: 143347

## Ice in volcanic clouds: where and when?

**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
- 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

**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

## 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

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

- ~2 MT ice, no fine ash detected
- ~80 KT SO2

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

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

## Ice mass in cloud is >2MT

**Ice mass in cloud is >2MT**
**SO****2**** sequestered**
**Salty rainfalls in a wide arc N and NW**
**Sea salt in the tephra**
**Ice may reduce residence time of ash and SO****2**

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

**Source of H****2****O? **
**Sea water entered the active vent at Vulcan.**

**Vulcan**

- Shuttle radar image, NASA

## Hekla, 26 February 2000

- 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.

## 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

- 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

## Cleveland Volcano, Aleutian Is

- GOES-W  4-5 Brightness Temp Difference Image

- D J Schneider
- USGS/AVO

## D J Schneider

- USGS/AVO

## D J Schneider

- USGS/AVO

## D J Schneider

- USGS/AVO

## D J Schneider

- USGS/AVO

## D J Schneider

- USGS/AVO

## D J Schneider

- USGS/AVO

## D J Schneider

- USGS/AVO

## Spurr, 19 Aug 1992

-   ~400 kT fine ash
-   ~300 kT SO2
-   No ice detected

****** ****> 2**

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

- Transparent fringes and opaque core

## ATHAM Eruption Conditions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 gas fraction: 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

## ash

- approximates observed height, width

- C M Riley,2002, Ph D dissert, Michigan Tech Univ
- C Textor et al, 2004, JGR in press

## ice

- ATHAM one hour simulation--
- Ice masses are <1% of ash

- C M Riley,2002, Ph D dissert, Michigan Tech Univ
- C Textor et al, 2004, JGR in press

## 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

- 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.

- Soufriére Hills 27 Dec 1997

## Soufriére Hills 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

- ~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 1991

- 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 Chichón 4 April 1982

- ~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

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

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

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

## Ice dominant

- <date/time>

**Ice dominant**

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

## Conclusions

- 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

## Questions?

- William I Rose,
- Michigan Technological University
-  Houghton, MI USA
- www.geo.mtu.edu/volcanoes/vc_web/

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

## Slide 35

## Slide 36

## In this format the color of each pixel is directly related to the ash burden.

## 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.

- 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.

## 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. 

- 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.

- High imaginary refractive index

- 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.

## Soufriére Hills, 27 Dec 1997

- 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.

## Transparent fringes and opaque core