Partial reflections: A source of weak VHF equatorial spreadFechoes

Calculations show that weak equatorial spread F observed at VHF could be caused by partial reflections from regions containing sharp electron density gradients. Gradients inferred from rocket and satellite data are sufficient to return signals more than an order of magnitude stronger than incoherent scatter from the same region. Data showing that the echoing regions drift with the ambient ionization and occur only in regions of strong density gradients are also consistent with this hypothesis. (AIP)