Volcanic ash and aerosol detection versus dust detection using GOES and MODIS imagery Bernadette...
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Transcript of Volcanic ash and aerosol detection versus dust detection using GOES and MODIS imagery Bernadette...
Volcanic ash and aerosol detection versus dust
detection using GOES and MODIS imagery
Bernadette ConnellCooperative Institute for Research in the Atmosphere
Colorado State University
2nd International Conference on Volcanic Ash and Aviation SafetyJune 21-24, 2004
Alexandria, Virginia, USA
Main Features“Easy” to implement techniques:
BT11.0um-BT12.0um
BT11.0um-BT3.9um (night)Estimated “reflected” 3.9um (day)False color 3.9/11.0/12.0um product BT8.5um-BT12.0um (ash and/or aerosol)
Examples of volcanic constituents vs. dust with GOES and MODIS data
Ash/Dust in the 3.9 – 11.0 um range• DAY: higher reflectance for ash/dust clouds and water
droplets; lower reflectance for ice particles• NIGHT: BT11.0-BT3.9 = negative for thin ash/dust clouds
= negative for ice cloud = positive for water cloud
Volcanic Aerosol vs. Ash/Dust in the 8.5 – 12.0 um range
• BT8.3um – BT12.0um = negative for SO2 and H2SO4 • BT8.3um – BT12.0um = negative for silicates, but sensitive to
particle size.
Ash/Dust in the 11.0 – 12.0 um range• BT11.0um-BT12.0um = negative for ash/dust
= positive for ice/water cloud
Popocatepetl Volcano, Mexico22 January, 2001 22:45 UTCGOES-8 imagery
Visible 3.9 um
10.7 um
Popocatepetl Volcano, Mexico22 January, 2001 22:45 UTCGOES-8 imagery
GOES imagery and products 23 January 2001 04:45 UTC
Popocatepetl, Mexico
10.7 um BT10.7-BT3.9
BT10.7-BT12.0False color: 10.9/BT10.7-BT12.0/BT10.7-BT3.9
GOES-8 BT10.7-BT12.0 MODIS Terra BT11.0-BT12.0
MODIS Terra BT8.5-BT12.0
Popocatepetl, Mexico
22 January, 2001 04:45 UTC GOES, 04:50 UTC MODIS
3 8 13 18Hour after eruption
-12
-10
-8
-6
-4
-2
larg
es
t B
T1
0.7
- B
T1
2.0
Popocatepetl, 22 January 2001Montserrat, 21 October 1997Montserrat second burst Reventador, 3 November 2002
18 April, 2001 19:30 UTC
DUST detection with GOES imagery
visible 10.7 um
BT10.7-BT12.0 Reflectance
DUST detection
18 April, 2001 19:30 UTC
MODIS Aqua true colorGOES-8 BT10.7-BT12.0
MODIS Aqua BT11.0-BT12.0 MODIS Aqua BT8.5-BT12.0
Summary remarks and points to ponder
• Variability of eruption cloud:
If multi-channel imagery is available, use it!
• What is the significance of large (or small)
BT10.7-BT12.0?
• What are we seeing using the 8.x um region (ash/dust/aerosol)?
• How can we best combine this information with other information on SO2 detection?