Volcanic Cloud Data Retrospectively
We do this as part of our
research, to thoroughly study the examples of volcanic clouds
around the world, after the eruption--sometimes long after!
Finding the data takes time to do.
Most satellites operate all
the time, and eruptions are rare. Eruptions that can be seen by
the satellites (those that are big enough, and go higher than the
local clouds, and last long enough to be detectable when the
satellite finally images) are much rarer. So the first thing we
need to know is:
was there an eruption?
usually be determined via the web, after some delay.
For recent activity try the
Volcanism Network: If you are looking for an eruption within
the last couple months, you will have to go to preliminary
reports: Alternatively there is a whole host of other sites to
find out about activity, including volcano
observatories and press
One issue here is that you
must be sure of the local time and universal
time. If you haven't mastered this,
you won't succeed.
the eruption "visible" from space?
was the eruption "visible" by the satellite? This is
really difficult to answer, unless you are lucky. To be lucky is
to find out someone has already found out that it is visible. Some
examples of where you might find this out: a. from VAACs
(Volcanic ash Advisory Centers): One center that frequently
tells when it detects volcanic clouds is the Washington
VAAC. Messages with attached graphics are especially helpful!
If you want TOMS data, you
should see if the eruption happened at or slightly before "solar
noon" at the volcano locality. This may not be the same as
the local 1200 hour-- you should check this. TOMS data is only
available around solar noon, so eruptions that happen just after
noon are often missed because the clouds they produce dissipate
before they are imaged. Since TOMS has a large resolution,
it is a good test to see if cloud/plume could be seen by other
satellites. If TOMS does see, then the other sensors will be
able to detect it as long as it was in the right place at the
Once you find a good
candidate, where there should be data, then you must actually get
A. For TOMS data: see the
TOMS site and follow
B. For browsing and ordering
AVHRR, use the NOAA site:
You will need to register
and get an account. Plan ahead where you will put these data!
C. For MODIS and other Terra
data: the EOS
Data Gateway is a good place to start. For direct links
to MODIS data, click here.
Having trouble? Refer to the
user guide developed by Matt Watson
D. Useful links for GOES
data: (GOES data are much more of a problem, because there is so
For a general look at data
sources try NOAA
(Gary Ellrod) or Goddard
list of GOES servers
data for the last few days: (includes raw data)
from the GOES Volcano watch examples:
source of GOES data (NOAA-NCDC):
Some very useful browsing
sites which highlight GOES volcano data in real-time (these are
useful if you are looking for current or very recent activity):
E. ASTER data can be found
at the EOS
Data Gateway or on the ASTER
homepage. A word of caution: they have begun charging
$55.00 for some of the datasets.
F. HIRS/2 data can be
obtained from the EUMETSAT
Data, Products, and Services page