Description of RN release scenario

The hypothetical nuclear explosion started on January 18 at 16:12 UTC at 174.86E and 41.89S, i.e. 50 km South of Wellington (New Zealand) in the middle of the Pacific Part of the Cook Strait between the South and the North Island of New Zealand.

1.3 PentaBq of tracer material was released equally distributed between surface and 150 m. The release duration was 3 hours.

At the release day the prevailing winds where rather weak coming from SE or E. The transport situation became more complex approximately 24 hours later when a change of the wind direction towards west developed from South. Hence during the 2nd 24 hours of dispersion the plume was sheared and lateral dispersed with the northern part still emerging towards North-West and the station NZP47 (Kaitaia) whereas the southern part of the plume was dispersed towards east and the Chatam Islands (NZP46), respectively.

After 3 days the aforementioned wind direction change towards west had gathered the whole plume including the parts across NZP46. In the following week this plume was transported towards South America while experiencing strong lateral and vertical dispersion.

At the 23 January, 18 UTC the plume reaches the Atlantic coast of Patagonia (Argentina). Obviously this part of the plume was rapidly transported in elevated layers and later downmixed on the leeward side of the Anden mountain chain. At this time the main body of the surface layer plume is still 50 degrees in Longitudes more western.

During the final 4 days of the Scenario the surface layer concentrations across Argentina, Chile, South Brasil and the South-Western Atlantic increase from imports that followed both major import paths, the slower surface level one and the faster upper level one that took place across the Southern Pacific Ocean. This explains why after a rather silent measurement period during the 25th and 26th of January (only 2 detections per day) the number of detections per day increases to 4 at the final day (29th of January),

The most western edge of the plume emerges towards lower latitudes where it comes into a regime of easterly winds taking it back towards Australia. However this plume part manages to touch none of the surrounding stations (AUP04, AUP06, FJP26, NZP46, CKP23, FRP27). Some of them are missed by less than 100 km distance

After 9 days of dispersion the plume extends across the half of the southern Hemisphere from 155E to 5W (seen from West to East). In total, the whole explosion would have caused 24 detections at 27 different stations within 9 days. The next station to be touched at the following day10 would have been GBP68 at the eastern edge of the plume.

"Event Creators Email" as produced by the PTS Scenario Creator Software (comprising a list of all detections with arrival times) click here