hae ABSTRACT ‘The purpose of this report is to present ‘analysis of the meteorological aspects of Operation IVY, to document the radiological data, and to interpret the analysis and data for guidance J L. ake in future Pacific tests. Fallout data was collected by the Atomic Energy Commscion on a world-wide network of gummed paper stations, supplemented _ by a few air filters, the radiological analysis being carried out by the New York Operations Office of the AtomicEnergy Commission. © '. Documentation of this data is in the form of maps showing the daily collections of beta activity at every sampling station used during this. operation. Meteorological analysis of the world-wide dispersion of debris from the MIXE and KING tests is best presented by dividing each cloud ‘into three separate layers - the trade wind layer (surface to about 30,000 feet), the upper troposphere layer (30,000 feet to 355000 feet) and the stratosphere layer (55,000 feet to cloud top). Schematic diagrams showing daily outlines of these layers as well as maps of daily radioactive surface deposi- tion are presented and discussed. The trade wind layer of both clouds moved away from the test site toward the west, a southern portion continuing westward while a segment from the’ northern edge dbase i its Wheat aad split off to curve toward the north-and then eastward toward North America. Direction of transport of the upper troposphere and stratosphere layers of the debris was variable although movement ' . was essentially zonal (east and west).. The effects of transport and diffusion are discussed and it is concluded that no data positively requires fallout of particles fron debristhat initially|stabilized in the> stratosphere. - Average activity ‘of surface depositionis increased. by precipi_ tation, but the increase in the United States for this operation is oe vid -