Remote Sensing of Volcanic Eruption Clouds Using GOES
David J. Schneider and William I. Rose
Department of Geological Engineering and Geophysics
Michigan Technological University
Introduction
During the past 15 years, there have been more the 80 incidents of jet aircraft
encountering volcanic clouds. Seven of these incidents resulted in the
in-flight loss of engine power, which could have resulted in the crash of the
aircraft, and repair costs (up to mid-1994) have been estimated at more than
$200 million. [Casdevall, 1994; U.S. Geological Survey Bulletin 2047.]
As a result of these encounters, there has been research done on the satellite
detection and tracking of volcanic clouds using the
Advanced Very High Resolution Radiometer (AVHRR). This research has shown
that it is possible to detect and track volcanic clouds using a dual
thermal-IR
proceedure.
The new generation of GOES imagers ,
currently aboard GOES-8 and GOES-9, now
have a dual thermal-IR capability which is similar to the AVHRR. Thus, it
should be possible to use data from this sensor to detect and track volcanic
clouds using a technique which is analogous to that used with AVHRR.
This document reports on a preliminary test of GOES imager data to
detect and discriminate volcanic clouds. Images of the relatively minor
eruption of
Popocatepetl Volcano, Mexico (March 10-11, 1996) were analyzed
using a two band technique, and the results show that it is possible to
to detect small volcanic clouds using GOES.
Two Channel GOES Discrimination of Volcanic Clouds
Thermal image data from two channels of the GOES-8 satellite
were used in this study
(Data courtesy of LSU Earth Scan Lab), and were rectified to an
equal area projection from the standard GOES image format. Band 4 (10.2 to
11.2 um) minus band 5 (11.5 to 12.5 um) brightness temperature difference
images are used to detect the volcanic cloud, and distinguish it from
meteorological clouds. Research using AVHRR data has shown that volcanic clouds
have negative band 4 minus 5 brightness temperature differences (Prata, 1989, Geophysical
Research Letters; Schneider et al., 1995 U.S. Geological Survey Bulletin
2139 ), while meteorological clouds generally have positive brightness
temperature differences (Yamanouchi et al, 1987 Journal of the
Meteorological Society of Japan). Since the GOES imager collects data at
wavelengths which are similar to the AVHRR, it is thought that band 4-5 technique
should yield similar results.
The band subtraction technique is demonstrated in
the images below, from the relatively minor eruption of Popocatepetl Volcano
on March 10-11, 1996. The image on the left is a band 4 image, and the image on the
right is the corresponding band 4-5 image. The location of the volcano is indicated
by the red dot. In the band 4 image (left) bright features, such as high clouds, are
cold, and dark features, such as land, is warm. Note that although a small bright
feature exists near the volcano, it looks very similar to other features. By comparison,
in the band 4-5 image (right), bright features have a negitive brightness temperature difference,
while dark features have a positive differences. In this image, the volcanic cloud can
be clearly discriminated from other features.
Volcanic Cloud Animation
Under ideal circumstances, it is possible to get a "snapshot" of volcanic
cloud activity every 15 minutes. However, in our study, we constructed an
MPEG of the March 10-11 1996 volcanic cloud from Popocatepetl at 30 minute
intervals. This animination covers the time period from 1715UT March 10 to
0645UT March 11, and shows the volcanic cloud as discriminated by the
band 4 - band 5 procedure outlined above. Only negitive brightness temperature
differences are depicted: The color scheme ranges from 0 (blue) to -3 (red) degrees Celsius.
This page maintained by Dave Schneider (djschnei@mtu.edu)
