Studies on the Propagation of Loran-A Ground Wave…I : On the Velocity of propagation as the Loran-A Ground Wave passes over the sea-surface

Abstract

The time differences of Loran-A rates (2S6, 2S7, 2H6, 2H7) were measured at the fixed points of Hiraiwa, Sumiyoshi, Toi and Kadokura on the southern Kyushu. The following results were obtained upon the investigation of the velocity of propagation as the Loran-A Ground Waves passed over the sea-surface ; 1) It was confirned that the velocity of propagation of Loran-A Ground Waves over the sea-surface are faster than that of the standard waves used on the computed Loran-A Ground Wave table. 2) When the fronts which extend from a well developed extratropical cyclone exist on these particular routs of propagation, there are common phenomena of noise or fading and accurate measurment may be hard or impossible. 3) It is surmised that the velocity of propagation of the Loran-A Ground Wave is faster in proportion to the sea-surface when the temperature rises. In the southern waters of Kyusyu, it is suggested that the value of ground wave correction may be stated with the empirical equation Y=-0.000233X. (Y...deviation in micro second, X...sea-surface temperature coeficient). 4) When a Loran-A ground wave passes over the area of Kuroshio, it is surmised that the Loran-A signal will be somewhat delayed. It is supposed that the delay-rate is 3.2 micro seconds per 100miles over the area of Kuroshio.