Prediction of Cs-137 deposition from atmospheric nuclear weapons tests within the Arctic

A method of predicting the spatial distribution of Cs-137 deposition in fal lout in the Arctic from atmospheric nuclear weapons testing, developed duri ng the Arctic Monitoring and Assessment Programme (AMAP), is described. The method uses a relationship between deposition and precipitation at Tromso (Norway) calculated for each year since 1955, which is spread over the Arct ic using a global precipitation data set within a geographical information system. The advantages of this approach include the ability to cover the wh ole Arctic area and to predict Cs-137 deposition, either integrated or deca y corrected (cumulative), for any 0.5x0.5 degrees unit for any year. For la nd north of 60 degrees N, the areas with the lowest estimated ground Cs-137 deposition from nuclear weapons testing are the Russian far north east, no rth Greenland and northern Canada. The highest estimated ground deposition occurred in the coastal areas of Alaska, the southern tip of Greenland, wes tern Canada, Iceland and the western coast of Norway. Predicted differences in the spatial distribution of global fallout are generally consistent wit h the trends observed by the United Nations Scientific Committee on the Eff ects of Atomic Radiation (UNSCEAR) and with reported measurements in the re gion above 60 degrees N. A comparison of the predicted cumulative Cs-137 de position with measured values gave a significant correlation (p < 0.001). H owever, the current predicted deposition would probably underestimate globa l fallout deposition in areas receiving little precipitation and areas clos e to the test site. (C) 1999 Elsevier Science Ltd. All rights reserved.