SECRET Chapter | INTRODUCTION 1.1 OBJECTIVES lelel Rising ¥2 Layer The first objective of this experiment was to firmly establish the cause-and-effect relationships for an ionospheric phenomenon first observed following Shot Mike of Operation IVY, namely, the large ine — crease in virtual height of the F2 layer and associated effects. 1.1.2 Distant Effects Tha second objective was to obtain corroborative data on effects at a great distance, first observed for Shot Mike of Operation IVY, in order to determine the vossibility of the use cf such effects as a . means of long-range detection and to determine whether eny indication | of the magnitude of the yield could be cbtained at distant locations. 1.1.3 Upper Ionospheric Knowledge It was also anticipated that detailed study of veth the local and the distant data would provide a better insight into the mecha~ nisms involved in F2-leyer phenomena, thus furthering the state of knowledge of the upper ionosphere. wiole4 Effects of Blast Wave on Lower Ionosvhere This experiment also furnished the opportunity to continue to investigate the effects of the blast wave on the ionedensity distribution in the E and Fl layers of the ‘onosphere and to study the ab- sorptive effects occurring below the E region. 1.2 BACKGROUND 1.201 Rising F2 Layer Following Shot Mike of Operation IVY, the F2 layer was observed to rise to abnormal heights, and its ion density, measured by critical SECRET RESTRICTED. DATA