Major step forward in detecting
nuclear explosions


Geneva/Vienna 1 September 2008 - The ability to detect the location of possible nuclear explosions will be significantly enhanced following the provisional entry into operation today (September 1st, 2008) of a joint response system of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and the World Meteorological Organization (WMO).

By applying a technique called Atmospheric Transport Modelling (ATM), the three-dimensional travel path of a radionuclide particle is backtracked from where it was detected by a monitoring station, to the area where it may have originated. This process is called source region attribution. Similar methods, although less sophisticated than those employed today, were already used in April 1986 by Swedish experts to attribute the radioactive cloud over Sweden to the Chernobyl reactor catastrophe – even before it became public.

Through the input of WMO’s high-quality global meteorological data, the CTBTO will be able to considerably improve its ATM calculations for radioactive particles detected by any of the 80 radionuclide stations of the CTBTO International Monitoring System (IMS), which is currently being built.

In the next step, referred to as data fusion, the results of ATM are compared to the data harvested through the other verification technologies (the so-called waveform technologies: seismic, hydroacoustic and infrasound). The synergy of both allows for a much more accurate location of a potential nuclear explosion. The more precisely the verification system can determine the location of a possible nuclear explosion at this point, the greater the chances of a subsequent on-site inspection finding concrete evidence of a recent nuclear test.

As the CTBTO-WMO response system becomes operational, the CTBTO will be able to send requests for assistance in the case of suspicious radionuclide detections directly to nine WMO Regional Specialized Meteorological Centres/National Meteorological Centres around the world. These centres will then submit their computations to the CTBTO as fast as is technically feasible but within 24 hours at the latest.

Cooperation between the CTBTO and the WMO dates back to 2000 and was enshrined in an Agreement in 2003.  Annual atmospheric backtracking exercises between the CTBTO and WMO Centres have been taking place since 2003, with the next one scheduled to be held within the next few months. In addition, unannounced system tests will be carried out every quarter. WMO has been involved in international efforts to monitor of nuclear tests since the 1990s, when negotiations on the Comprehensive Nuclear-Test-Ban Treaty (CTBT) within the UN Conference on Disarmament were still ongoing.  By offering the use of its Global Telecommunications System for data exchange, WMO enabled the experts taking part in the negotiations to make great advances toward designing what later became the model for the current IMS.

For further information on the CTBT, please see – your resource on ending nuclear testing, 
or contact: Annika Thunborg,
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