Anomalous Multiple Traces Below F sub O E in High Gain Ionograms Recorded at Sodankylaa

摘要

Anomalous multiple trace patterns were studied. Ionograms were simulated and the intensities of the multiple echoes were estimated to study anomalous multiple trace patterns. The virtual heights of the two reflection levels were calculated for the different frequencies, using electron density profiles. The group path was obtained by integrating the group refraction index from the transmitter to the reflection level. A correlation exists between the daily variations of the occurrence of the multiples and high type sporadic E-layers. The multiples are caused by vertically propagating waves coupled from o to z-mode in the lower E-region which bounce back and forth between a partially transparent sporadic E-layer and the lower F-region.