Gigahertz scintillations associated with equatorial patches

Abstract

In a program designed to compare measurements of scintillation activity in the equatorial anomaly region, observations were made of satellite beacon signals transmitting at frequencies ranging from 137 MHz to 7 GHz. Recordings were made at Ascension Island in January–February 1981, during a month of very high solar flux and a high occurrence of scintillations. Saturation was noted in the VHF‐UHF range with levels of 8 dB peak to peak at 4 GHz and 3 dB peak to peak at 7 GHz. Statistics of occurrence of various levels for 1.5 and 4 GHz are given in the paper. The hypotheses of vertical or horizontal irregularity sheets or rods within the patches of irregularities were examined with data from the Global Positioning System satellites. Vertical sheets were eliminated as a possibility. A comparison of scintillations with 6300‐Å airglow images, which map regions of depleted electron density over the entire sky, showed that in the anomaly region, maximum scintillation activity occurs within the patch and not at the walls of the patch.