CHAPTER 1 BASIC DATA . 1.1 INTRODUCTION . Operation IVY, the fourth series of nuclear tests by the Atomic Energy Comm ssion to be conducted at the proving grounds in the Marshall Islands of the Pacific Ocean ‘consisted of two - high yield nuclear devices, The first, MIKE, was detonated at 1915 GCT, 31 October 1952 and the second, KING, at 2330 GCT,. 4 | ‘ . 45 November 1952, both at the Eniwetok Proving Growmds. ‘The fallout from these tests was of particular interest because of - several unique conditions. First, the extremaly high yield of the tests posed new questions as to possible health or industrial hazard, second, there had never been any extensive groud monitoring system for previous Pacific tests, and third, no previous ' atomic cloud had reachsd the altitudes estimated for the MIKE cloud, 120, 000-110, 000 feet ebove sea level. The purpose of ‘this report is ‘to integrate the radiological end meteorological observations and achieve the following - objectives: © silsate 1. Full documentation of the fallout data. 2. Meteorological interpretation of the fallout data, including a reconstruction of the mst probable paths followed by the ‘debris. 3. Use of VX data to predict fallout f. or future tests. ‘h. Evaluation of atomic debris as a tracer for meteoro- logical research. ind. 1.2 BASIC METEOROLOGICAL DATs Aithough the network of upper-air observing stations in the vicinity of the Eniwetok Proving Grounds was increased for the IVY test period, it was still pitifully small in comparison with. that in the United States. (It would correspond roughly to stations in Texas, Montana, and Mexico if transferred to the Kevada Proving Grounds!) Analysis of air flow patterns in the tropics is further hampered y the breakdown of the geostrophic -l-