Transcript Central Facility Presentation

APPLICATIONS OF
METEOSAT SECOND
GENERATION (MSG)
VOLCANIC ASH & SO2 DETECTION
Authors:
J. Kerkmann (EUMETSAT), B. Connell (CIRA)
[email protected]
[email protected]
Contributors: F. Prata (CSIRO), S. Watkin (Met Office)
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Outline
1) Background: detection of volcanic ash for
aviation hazards
2) Background: detection of volcanic ash & SO2
for human health hazards
3) Techniques for ash detection
4) Examples
5) Limitations
6) Selected References
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1. Background: Detection of Volcanic Ash for
Aviation Hazards
Eruption of Grimsvötn, 2 Nov 2004
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Motivation
“Ash clouds are not an everyday issue and they
do not provide frequent hazard.
But if encountered, volcanic ash can spoil your
entire day.”
(Engen, 1994)
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Motivation
• Between 1975 and 1994, more than 80 jet airplanes
were damaged due to unplanned encounters with
drifting clouds of volcanic ash.
• Seven of these encounters caused in-flight loss of jet
engine power, .. Putting at severe risk more than
1,500 passengers.
• The repair and replacement costs associated with
with airplane-ash cloud encounters are high and have
exceeded $200 million.
(Casadevall, 1994)
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This picture shows the blades from a jet turbine which ingested airborne
volcanic ash. The ash was melted and formed a glassy coating on the blades,
covering cooling passeges and destroying the engine's efficiency.
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More Background
• The primary cause of in-flight engine loss was the
accumulation of melted and resolidified ash on
interior engine vents which reduced the effective
flow of air through the engine, causing it to stall.
• Volcanic ash is abrasive, mildly corrosive, and
conductive. Airframes and engine components can
be destroyed. Windshields are especially
vulnerable to abrasion and crazing.
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Global volcano distribution. Open triangles represent volcanoes believed to have
erupted within the last 10,000 years, and filled triangles indicate those that have
erupted within the 20th century.
(Simkin, 1994)
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Important Aviation Considerations
• The height that columns can reach and then disperse
their load of ash into the prevailing winds.
• The column rise rate.
• The content of fine ash that may be suspended or
falling in the atmosphere for considerable distances
or periods.
• The duration of the ash clouds.
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Importance of Remote Sensing
• Global coverage
• Allows for tracking of the plume both during the day
and at night.
– Provides information in remote locations
– Can be used in conjunction with soundings to
determine plume height and probable plume
movement.
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Three parts or regions of an eruption column: gas thrust, convective thrust, and umbrella.
(Self and Walker, 1994)
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Three possible modes of behavior of eruption columns - intensity of eruption increases from left
to right. Wind is from the left in each case. At side of each diagram are shown normalized
velocity (v) profiles versus height (h) for these columns. Left, weak isolated thermals, which are
influenced by the wind. Center, a higher intensity buoyant column, influenced by wind only at
the top. Right, a high intensity, superbuoyant column with a pronounced umbrella region.
(Self and Walker, 1994)
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2. Background: Detection of Volcanic Ash and
SO2 for Human Health Hazards
Mt. Etna Eruption in October 2002
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Volcanic Ash: Effects on Human Health
• Respiratory symptons: potential respiratory symptoms from the
inhalation of volcanic ash.
• Eye symptons: because volcanic ash is abrasive, people typically
experience eye discomfort or irritation during and after ash fall,
especially among those that use contact lenses.
• Skin irritation: minor skin irritations are sometimes reported
following ashfall.
• Mechanical effects: roof collapses and automobile accidents. The
weight of volcanic ash on roofs can lead to their collapse, especially
if the ash is wet and the building is not designed to support a heavy
load.
from: U.S. Geological Survey
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Volcanic Ash: Effects on Human Health
Principal health effects caused by ash fall from selected historical eruptions
from: U.S. Geological Survey
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SO2: Effects on Human Health
• Stomach illnesses
• Respiratory and bone diseases
• Fluoride overdoses cause a variety of sickness and turning people's
teeth transparent
Other Effects
• SO2 produces acid precipitation
• Destruction of land by volcanic fallout
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3. Techniques for Ash Detection
Eruption of Grimsvötn, 2 Nov 2004
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Techniques for Ash Detection
Use of single-channel imagery:
• HRV (channel 12)
• IR3.9 (reflected component)
Use of multi-channel imagery:
• 12.0 m – 10.8 m brightness temperature difference (BTD)
• 3.9 m - 10.8 m BTD
• 10.8 m - 8.7 m BTD
• 13.4 m - 7.3 m BTD
• 3.9 / 8.7 / /10.7 / 12.0 / 13.4 m combined product
RECALL: emissivity + reflectivity + transmissivity = 1
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HRV
• Difficulty to detect thin ash clouds
• Detection depends on reflectivity of underlying surface
(detection easier over dark ocean)
• Detection depends on satellite and sun angles (detection
easier in the early morning hours)
• Animation helps!
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HRV: Example
Met-8, 2 September 2005, 06:00 UTC, Mt. Etna, Sicily
Click on the icon to see the animation
(05:30-07:15 UTC, MPG, 1533 KB) !
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IR12.0 - IR10.8 BTD
• Volcanic ash clouds with a high concentration of silicate
particles exhibit optical properties in the infrared (8-13 m)
that can be used to discriminate them from normal water/ice
clouds.
• Emissivity of silicate particles is lower at 10.8 m than at
12.0 m
• Emissivity of water/ice particles is higher at 10.8 m than
at 12.0 m
==> IR12.0 - IR10.8 BTD tends to be positive for ash
clouds with a high concentration of silicate particles (also
for dust storms and desert surfaces) !
Remember: This BTD also depends on height of the
cloud/humidity content.
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IR12.0 - IR10.8 BTD
Focus on zenith angles < 50 degrees:
For quartz:
For volcanic dust:
For ice and water
IR11.8 - IR10.9 = positive
IR11.8 - IR10.9 =~no difference
IR11.8 - IR10.9 = negative
Satellite simulated brightness temperatures as a function of zenith angle for quartz and
volcanic dust clouds (left) and water and ice clouds (right) at 10.9 m and 11.8 m
(Prata and Barton, 1994)
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IR12.0 - IR10.8 BTD: Example
negative differences
IR10.7
positive differences
Difference IR12.0 - IR10.7
GOES-8, 20 July 2000, 16:39 UTC, Lascar, Chile
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IR12.0 - IR10.8 BTD: Scatterplot
Temperature Difference (K) (12.0 um - 10.7 um)
Lascar, Chile July 20 2000 16:39 UTC
ash plume
ash plume
thin cirrus
ocean stratus
10
6
2
-2
-6
250
260
270
280
290
300
Temperature (K) 10.7 um
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IR3.9 - IR10.8 BTD
• The 3.9 um channel has both a strong reflected component
during the day, as well as an emitted terrestrial
component.
• At night, there is no reflected component – only the
emitted (and transmitted) components.
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IR3.9 - IR10.8 BTD: Day-Time Examples
MSG-1, 2 Nov 2004, 14:00 UTC
Eruption of Grimsvötn
Range: 0 K (black) to +50 K (white)
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MSG-1, 25 Jun 2003, 10:00 UTC
Dust storms Middle East
Range: -5 K (black) to +45 K (white)
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IR10.8 - IR8.7 BTD
• Volcanic plumes with a high concentration of sulfur dioxide
(SO2) can be detected in the IR10.8 - IR8.7 BTD image
(because of SO2 absorption band at IR8.7)
• SO2 clouds are more transparent at IR10.8 than at IR8.7
(i.e. positive IR10.8 - IR8.7 BTD)
• Ice clouds are more transparent at IR8.7 than at IR10.8
(i.e. negative IR10.8 - IR8.7 BTD)
• IR10.8 - IR8.7 BTD for SO2 clouds depends on lapse rate
and can be negative in case of temperature inversions
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IR13.4 - WV7.3 BTD
• Volcanic plumes with a high concentration of sulfur dioxide
(SO2) can also be detected in the IR13.4 - WV7.3 BTD
image (because of SO2 absorption band at IR13.4)
• However, IR13.4 - WV7.3 BTD is strongly influenced by
surface temperature variations and by changes in the water
vapour content so that the signal from the SO2 plume is
only visible at certain times (e.g. at night in the case of the
Nyiragongo eruption in July 2004)
• Also, IR13.4 - WV7.3 not sensitive to low-level SO2 clouds
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Transmittance of SO2 Clouds
(From CIMSS, University of Wisconsin and CSIRO, Melbourne)
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IR10.8 - IR8.7 BTD: Example
Nyiragongo
IR10.8
IR10.8 - IR8.7
MSG-1, 12 July 2004, 08:15 UTC
Nyiragongo eruption, Dem. Republic of the Congo
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Combined Products
Experimental Volcanic Ash Product (Ellrod et al. 2001)
B = C + m [T(12.0) - T(10.7)] + [T(3.9) - T(10.7)]
with:
B= output brightness value
C=constant=60
(determined empirically)
M=scaling factor=10
(determined empirically)
T= brightness temperature at (wavelength)
Experimental Ash Product
Lascar, Chile, 20 July 2000, 16:39 UTC
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Lascar, Chile July 20, 2000 16:39 UTC
ash plume
ash plume
thin cirrus
ocean stratus
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Combined Products
Possible RGB Composites
• RGB VIS0.8, IR10.8-IR8.7, IR12.0-IR8.7
(for SO2 clouds)
• RGB IR12.0-IR10.8, IR10.8-IR8.7, IR10.8
(similar to dust RGB, but different ranges)
• RGB IR12.0-IR10.8, IR10.8-IR3.9, IR10.8
(similar to fog RGB, but different ranges)
• RGB IR12.0-IR10.8, IR3.9-IR10.8, IR10.8-IR8.7
• RGB HRV, HRV, IR10.8-IR12.0
...
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4. Examples
Eruption of Pinatubo, June 1991
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Volcanic Eruption, 10 May 2004
Mt. Nyamuragira
Democratic Republic of the Congo
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MSG VIS Channels, 06:00 UTC
Mt. Nyamuragira

Channel 01 (VIS0.6)
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
Channel 02 (VIS0.8)
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MSG NIR Channels, 06:00 UTC

Channel 03 (NIR1.6)
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
Channel 04 (IR3.9)
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MSG IR Channels, 06:00 UTC

Channel 07 (IR8.7)
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
Channel 09 (IR10.8)
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MSG HRV Channel, 06:00 UTC

Rwanda
Lake
Victoria
SO2 plume
faintly visible
Burundi
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MSG Differences IR Channels, 06:00 UTC


The SO2 plume is best visible in the IR10.8 IR8.7 brightness temperature difference
image. As can be seen in the animation,
large parts of Rwanda and Burundi are
covered by the SO2 cloud, which moves in a
south-easterly direction
Difference IR10.8 - IR8.7
Range: -3 K (black) to +8 K (white)
Difference IR12.0 - IR8.7
Range: -3 K (black) to +8 K (white)
Click on the icon to see the animation
(00:00-12:00 UTC, AVI, 6451 KB) !
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IR10.8 - IR8.7 Colour Enhancement
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MSG IR10.8 - IR8.7 vs IR13.4 - IR7.3

Difference IR10.8 - IR8.7
Range: -3 K (black) to +8 K (white)
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
Difference IR13.4 - WV7.3
Range: 0 K (black) to +22 K (white)
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RGB VIS0.8, IR10.8-IR8.7, IR12.0-IR8.7
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Volcanic Eruption, 12 July 2004
Mt. Nyiragongo
Democratic Republic of the Congo
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Channel 12 (HRV) Shows Time Evolution
Mt. Nyiragongo

Lake
Kivu
Click on the icon
to see the animation
(06:00-12:00 UTC,
AVI, 3085 KB) !
MSG-1, 12 July 2004, 08:15 ITC, Channel 12 (HRV)
The animation shows two plumes coming from two locations close to each other: a faint plume
extending southwest of the volcano, a thick plume extending to the southeast and an arc of ash
stretching over Lake Kivu between the two plumes.
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MODIS gives
horizontal details
but does not show
time evolution
Terra MODIS, 12 July 2004, RGB Composite
Info on time evolution is not contained in single images from polar-orbiting satellites.
Thus, one could have thought that the thin plume was something like the remnants
of the plume from an earlier eruption.
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MSG IR Channels, 08:15 UTC

Channel 07 (IR8.7)

Channel 09 (IR10.8)
The thicker plume extending to the southeast can faintly
be detected in the infrared channels
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MSG IR10.8 - IR8.7 vs IR13.4 - IR7.3


IR13.4 - WV7.3 difference is strongly
influenced by surface temperature
variations and by changes in the
water vapour content so that the
signal from the SO2 plume is only
visible at certain times !
Difference IR10.8 - IR8.7
Range: -8 K (black) to +8 K (white)
Click on the icon to see the animation
(10-12 July, hourly, AVI, 6297 KB) !
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Difference IR13.4 - WV7.3
Range: -6 K (black) to +20 K (white)
Click on the icon to see the animation
(10-12 July, hourly, AVI, 6375 KB) !
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MSG Diff. IR12.0 - IR10.8, 08:15 UTC
Click on the icon to see the
animation (10-12 July, hourly,
AVI, 6389 KB) !

No ash plume visible !
(ash at high altitudes normally has a
distinctive positive IR12.0 - IR10.8
temperature difference of more than 2 K)
Difference IR12.0 - IR10.8
Range: -10 K (black) to +1 K (white)
•
•
•
•
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Conditions for seeing the ash plume !
semi-transparent ash clouds
small ash particles
large temperature difference between
ash cloud and underlying surface
low water content in ash cloud
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Sulphur Plant Explosion, 25 June 2003
Al-Mishraq , Mossul, Northern Iraq
- Biggest ever man-made sulphur dioxide plume -
"Observing the fire from space was the only way
to find out how severe it actually was, because there
was no way to monitor the pollution from the ground"
(Simon Carn, University of Maryland Baltimore County)
Terra, MODIS, 25 June 2003, 10:35 UTC, RGB composite
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Sulphur Plant Explosion, Al-Mishraq:
Some Figures
• The fire burned for almost a month
• A total of around 600,000 tonnes of sulphur dioxide was released by the
fire.
• To put that figure in context, the giant eruption of Mount St Helens in
1980 belched out about one million tonnes of sulphur dioxide
• The fire caused about $40m of damage to local crops - along with
respiratory problems in local people
• More than 40 percent of the trees lost their leaves in a radius of 100 km
from the plant
(BBC News)
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Channel 12 (HRV) Shows Time Evolution
Sulphur
Plant
Click on the icon
to see the animation
(02:00-08:00 UTC,
AVI, 3454 KB) !

MSG-1, 25 June 2003, 10:00 ITC, Channel 12 (HRV)
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MSG IR Channels, 10:00 UTC

Channel 07 (IR8.7)

Channel 09 (IR10.8)
During day-time, the IR8.7 channel was up to 21 K colder than the IR10.8 channel
due to strong absorption by the SO2 cloud of the radiation from the very hot surface
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MSG IR10.8 - IR8.7 vs IR13.4 - IR7.3


SO2 cloud was limited to the
Planetary Boundary Layer (PBL) and
thus not detectable by the WV7.3
channel, which has the peak of the
weighting function in the layer from
about 700 to 400 hPa (depending on
the humidity content) !
Difference IR10.8 - IR8.7
Range: -5 K (black) to +20 K (white)
Difference IR13.4 - WV7.3
Range: -5 K (black) to +22 K (white)
Click on the icon to see the animation
(00:00-12:00 UTC, AVI, 4617 KB) !
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RGB VIS0.6, IR10.8-IR8.7, IR12.0-IR8.7
Fire sulphur plant
Dust storms
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SCIAMACHY, Monthly Averaged SO2
Concentration
most of the SO2 plume went in
easterly direction, towards the
Caspian Sea, indicating prevailing
winds from the west during the
week(s) that followed the accident !
Source: University of Bremen
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Volcanic Eruption, 02 November 2004
Grimsvötn, Iceland
Eruption of Grimsvötn, 2 Nov 2004, Alexander H. Jarosch
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Eruption of Grimsvötn: Some Facts
• The eruption plume was first detected on 1 November by weather radar. It
reached an altitude of 13 km.
• On 2 November, there were eruptions pulsed resulting in a changing
eruption column height from 8-9 km up to 13-14 km
• On 3 November 2004, the ash plume reached Norway, Finland and
Sweden causing the diversion of trans-Atlantic flights to the south of
Iceland to avoid the ash cloud
• The Dutch airline KLM had to cancel 59 flights, stranding hundreds of
passengers at Amsterdam's Schiphol Airport
• The eruption of Grimsvötn volcano ended on 6 November 2004
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Significant
Weather
Chart
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Channel 12 (HRV) Shows Time Evolution
Shadow on lower-level clouds
Grimsvötn

Click on the icon
to see the animation
(08:45-14:00 UTC,
AVI, 5625 KB) !
MSG-1, 2 November 2004, 09:30 UTC, Channel 12 (HRV)
At 09:30 UTC, with the sun shining at low elevation angle from the south-east, the volcanic
cloud produces a distinct shadow on the lower- level clouds that surround the volcano
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Channel 12 (HRV) in Mercator Projection

MSG-1, 2 November 2004, 12:30 UTC, Channel 12 (HRV)
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MSG IR10.8 Channel
09:30 UTC

14:00 UTC

Animation of the IR10.8 channel data confirms the pulsating character of the Grimsvötn
eruption on 2 November 2004: between 12:00 and 13:30 UTC the top of the volcanic plume
cooled down from about -20°C to -55°C (11:00-14:00, AVI, 6565 KB)
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MSG IR10.8 - IR8.7 vs WV7.3 - IR13.4, 14:00 UTC


The existance of sulfur dioxide within the plume is confirmed by the WV7.3 - IR13.4 and the
IR10.8 - IR8.7 brightness temperature difference images at 14:00 UTC that clearly show the
volcanic plume !
Difference IR10.8 - IR8.7
Range: -5 K (black) to +5 K (white)
Click on the icon to see the animation
(11:00-14:00 UTC, AVI, 6567 KB) !
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Difference WV7.3 - IR13.4
Range: -10 K (black) to +10 K (white)
Click on the icon to see the animation
(11:00-14:00 UTC, AVI, 6565 KB) !
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MSG IR3.9 - IR10.8 vs IR10.8 - IR12.0, 14:00 UTC


From the IR10.8 - IR12.0 difference images it is difficult to confirm the presense of ash within
the volcanic plume. Probably, there was too much water vapour in the volcanic cloud and/or the
ash particles were too big/heavy so that most of them dropped down in the vicinity of the
volcano.
Difference IR3.9 - IR10.8
Range: 0 K (black) to +50 K (white)
Click on the icon to see the animation
(11:00-14:00 UTC, AVI, 6565 KB) !
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Difference IR10.8 - IR12.0
Range: -2 K (black) to +8 K (white)
Click on the icon to see the animation
(11:00-14:00 UTC, AVI, 6565 KB) !
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5. Limitations
Eruption of Mount St. Helens, 8 March 2005
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Challenges to using the 10.8-12.0 um
difference product
• For optically thick plumes, when water and ice are mixed with
the volcanic debris, the ‘ash’ signal may be confused
• Low ash concentrations can be difficult to detect
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Challenges to using the 3.9-10.8 um
difference product
• Limitations to measurements for cold scenes at 3.9 um:
– The steep slope of the Plank function at cold
temperatures (<-50 C), the instrument noise at 3.9 um
becomes very large
• Uncertainties with properties of
reflectance/emittance/transmittance of the ash cloud
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Other uses of satellite imagery for volcano
monitoring
• Hot spot detection (with IR3.9 channel)
• Determination of cloud height with VISIBLE shadow
technique (with HRV channel)
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SUMMARY
Detection of Volcanic Ash & SO2
• HRV: to monitor time evolution during day-time (problem
with very thin volcanic ash clouds)
• IR12.0 - IR10.8 for detection of ash clouds with high silicate
concentration (especially for thin, high-level ash clouds),
discriminates well between ash and ice clouds
• IR3.9 - IR10.8 also good (especially for thin, high-level ash
clouds), but no discrimination between ash and thin ice
clouds
• IR10.8 - IR8.7 for detection of SO2 clouds
• IR13.4 - WV7.3 less useful for detection of SO2 clouds
• Combined Products using IR12.0-IR10.8, IR3.9-IR10.8 and
IR10.8-IR8.7 !
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6. Selected References
Prata, A. J. 1989: Observations of volcanic ash clouds in the 10-12 um
window using AVHRR/2 data. Int. J. Remote Sensing, 10 (4 and
5), 751-761.
Engen; Cassadevall; Simkin; Self and Walker; Prata and Barton,
Schneider and Rose, and other articles can be found in: Casadevall,
T. J., 1994: Volcanic Ash and Aviation Safety: Proceedings of the
First International Symposium on Volcanic Ash and Aviation
Safety. U.S. Geological Survey Bulletin 2047.
Ellrod, G. P., B. H. Connell, and D. W. Hillger, 2001: Improved
detection of airborne volcanic ash using multispectral infrared
satellite data. J. Geophys. Res., 108 (D12), 6-1 to 6-13
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