DRegion lunar variations deduced from long-path 10.2-kilohertz phase measurements

Abstract

The relative phase of the 10.2‐kHz Omega signals propagating between Forestport, New York, and Trinidad was used to deduce semilunar components at 0400 and 1600 GMT for six 2‐month periods. The data extended from March 1, 1966, through September 1970. The average of the data phased according to the upper or lower lunar transit was subjected to harmonic analysis for a 15‐day period before and after the linear trend was removed from the average. The 15‐day periods at 0400 GMT during December and January and at 1600 GMT during February and March were significant at the 5% level. The phase of the 15‐day period changed regularly with season at 0400 and 1600 GMT, although not all seasonal components were significant. From VLF mode theory and observations the average amplitude of the 15‐day period was estimated to be 0.24 km at 85.5 km elevation (0400 GMT) and 0.06 km at 70 km elevation (1600 GMT).

The correlation of VLF propagation variations with atmospheric planetary-scale waves

“…Brady and Crombie (1963) corrected transmitter and receiver oscillator drifts by subtracting a parabolic variation of phase drift in order to study the effects of lunar tidal variations on the phase of VLF transmissions. The more recent use of cesium atomic standards for frequency reference at transmitters and receivers has enabled seasonal variations to be analyzed using VLF data with greater confidence (e. g., Noonkester, 1972). However, no connections have yet been made between disturbances observed with VLF transmissions and planetary scale fluctuations in the stratosphere.…”