Some results of sweep-frequency investigation in the low frequency band

Sweep-frequency techniques, long in use in high-frequency ionospheric research, have been used recently in low frequency research at the National Bureau of Standards. The discovery of a nighttime layer between the E- and F-layers, which is erratic in appearance, but which seems to have continuity with the daytime E-layer during sunset, is announced. Traces characteristic of magneto-ionic splitting are exhibited for the new layer and also for the low-level E-layer. Polarization and virtual height records of F-layer at night are shown and the effects of ionosphere storms on E- and F-regions are demonstrated. Daytime reflections have been recorded from three distinct E-region boundaries, each of which appears to be quite sharp in ion gradient. These extend from about 70 km to over 100 km in virtual height. Several recordings of turbulent conditions in the lower levels of the daytime E-region are shown.