Order number page 7 940406-171827-1 set 5 with LOFFICIAEGSE ONLY 110. PRIMARY TITLE (M) 72. 710. PERSONAL AUTHOR/AFFIL Utlaut, W.F. CORPORATE Ionospheric effects due to nuclear explosions. Project No. 8520-12-8510 t SOURCE National Bureau of Standards, States) t Boulder, ; CO (United 590430 ‘ 371. PUB. DATE (YYMMDD) Official Use Only 34. CLASSIF. LEVEL TEXT Extreme disturbances of the ionosphere were noted 950. ABSTRACT over the Pacific Ocean. These disturbances which were related to the high-altitude nuclear blasts over Johnston Island on August 1 and 12, 1958 were manifested by complete fadeouts on many radio circuits, abnormal magnetic perturbations, and a rare tropical aurora. It appears that prompt radiation from both nuclear tests 801. KEYWORD(S) caused increased lonization and absorption in the D region for a short interval of time. The higher altitude test caused an almost immediate increase in electron density in the F region, followed by a marked reduction in electron density, sufficient to prevent reflections of signals above 1 Mc, which was possibly attributable to increased recombination rate caused by influx of bomb residue. A similar reaction occurred after the lower level explosion, with a 45-min delay, but not to such an extent as to cause blackout. Graphical representations are given for f-plots of the ionospheric data taken at Maui, Hawaii, on both test dates. IONOSPHERIC BURSTS;HIGH ALTITUDE; IONOSPHERIC EFFECTS ; DISTURBANCES; ORANGE BURST; TEAK BURST; ATMOSPHERIC BURSTS; RADIO INTERFERENCE; ELECTRON DENSITY;BLACKOUT; F REGION;D REGION Ttem 13 150. 110. 710. REPORT NUMBER NP--9298 PRIMARY TITLE (M) The results of a physical and biological oceanographic survey at Eniwetok, September--October 1957 CORPORATE SOURCE Fish and Wildlife Service, Honolulu, HI (United States) 371. PUB. DATE (YYMMDD) 34. CLASSIF. LEVEL TEXT 950. ABSTRACT 580115 Official Use Only Results of an oceanographic survey in the vicinity of Eniwetok Atoll, 801. KEYWORD (S) 5003381 Marshall Islands, are presented. The observations included bathythermographs; m@teorology; vertical distribution of temperature, salinity, density, and dissolved oxygen; sea and swell; zooplankton sampling; night-light fishing; tuna school and bird flock sightings; and surface trolling and angling. ENIWETOK; ENIWETOK PROVING GROUND; OCEANOGRAPHY; METEOROLOGY; TEMPERATURE DISTRIBUTION; PLANKTON; FISHES; OFFICIAL USE ONLY