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From:
"Andrew Tupper (a/RD NT)" <A.Tupper@xxxxxxxxxx>
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Dear all,
Please find below for your information the text of a summary statement
that came out of a workshop on volcanic ash in late March. The meeting
web site is at
http://www.caa.govt.nz/Volcanic_Ash_Workshop/Volcanic_Ash_Workshop_home.htm
, although not for much longer as it was set up as a temporary site.
Papers given at the meeting can be found on that site, and some of them
will also appear in a planned special issue of the Springer journal
Natural Hazards.
best regards,
Andrew Tupper,
convener, Scientific Organising Committee.
___________________
W O R L D M E T E O R O L O G I C A L O R G A N I Z A T I O N
4th International Workshop on Volcanic Ash
Rotorua, New Zealand
26-30 March 2007
SUMMARY
The 4th International Workshop on Volcanic Ash was held in Rotorua, New
Zealand, from 26 to 30 March 2007. The meeting heard of progress in many
areas of the International Airways Volcano Watch (IAVW), including new
remote sensing techniques. So far, no fatal aircraft encounters with
volcanic ash have occurred, arguably as a result of the efforts of the
IAVW. However, the meeting noted with concern that there have been
several aviation incidents attributed to volcanic ash over recent years,
including the double engine flame-out of a twin-engined aircraft at
cruising levels over Papua New Guinea in July 2006.
The presentations given by the participants helped to identify areas of
progress, but also those remaining questions that need to be addressed
by both the scientific community and the operational users of the
information.
To improve the science that supports the International Airways Volcano
Watch, the following specific actions are suggested:
- In order to achieve rapid and reliable alerts to new ash-producing
eruptions, close monitoring of known, existing active volcanoes needs to
be assured by both local and remote means. While space-based remote
sensing has been instrumental in detecting many eruptions, the nature of
polar orbiting satellites with infrequent overpasses, the limitations of
some methods requiring daylight, and the ubiquitous presence of dense
cloud in many areas underline the need for local monitoring. Infrasound
measurements from the CTBTO or regional networks can improve detection,
but for some instances a time delay in the order of hours may currently
have to be accepted;
- Any realistic hope of forecasting eruptions is entirely dependent on
local monitoring by observatories. The meeting noted with concern that
the resources available to many volcano observatories are insufficient.
The meeting strongly encouraged States and international organizations
to undertake a co-ordinated international effort to help in particular
developing countries to establish and maintain effective volcano
observatories throughout the world. The meeting recognized that it would
be unrealistic to expect small island states and developing countries to
shoulder the cost of such observatory operations which are partly or
mostly in support of international aviation;
- The meeting supported the efforts underway to investigate eruption
source parameters as a means to improve ash dispersion forecasts;
- It was found that weather Radar is very useful for the detection of
eruptions, especially when volcanoes are near airports. There is a need
to better quantify the uncertainty in determining the eruption
characteristics from the radar data;
- Uncertainty on the correlation between actual threat to aviation from
ash and the presence of elevated concentrations of SO2, well-monitored
by remote sensing, requires further investigation, in particular for
eruptions including a pyroclastic flow, where SO2-rich and ash-rich
clouds may be found at different heights, and may thus take totally
different trajectories;
- Comparisons between different transport and dispersion models used by
the VAACs revealed a satisfactory consistency between different models
regarding the trajectories of plumes. However, further validation
studies are required, including comparison to observations as well as
between models;
- The meeting established a training sub-group to identify scientific
material needed for inclusion in training in support of the IAVW;
- There is no definition of a “safe concentration” of ash for different
aircraft, engine types or power settings. In order to give a reliable
and justifiable “all clear” once a plume has dispersed enough to be
undetectable, clear limits of ash content are required from both the
manufacturers and aviation licensing authorities.
------------------------------------------------------------------------------
Andrew Tupper
a/Regional Director
Bureau of Meteorology, Darwin, Australia
Ph: +61 8 8920 3801
Fax: +61 8 8920 3802
Mobile / Cell Phone: + 61 (0)417 897 324
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