デッカ双曲線の誤差の長期変化と電波伝搬速度

概要

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Our studies are based upon the measuring records at 13 observation sites within the coverage of the Kita-Kyushu Decca chain, through four years (1969-1973). These intense observations were done as much as one hour during the daytime daily, namely normally from 1030 to 1130 hours (JST) with readings every minutes, 10 days every month (1970-1973). In addition to this records, supplementary measurements were carried out at the isle of Tsunoshima in Summer (1978) and in Winter (1979), respectively 3 days. These measurments were done during the daytime by the reason why skywave contamination was not encountered. In each pattern of monthly mean at observation sites, the deviations varied respectively, especially in the case of the Red Pattern, the variations of monthly mean of deviations were observed seasonal rise and fall. This striking peak of the seasonal variations were observed through the winter period. This phenomenon should be explained as the result of the diminution in the propagation velocity. In consequense, the authors selected the three observation sites located on the isle to calculate the propagation velocity over the sea. As the result of comparing with the calculated propagation velocity over the sea between the summer period and the winter period, through the winter period, the propagation velocity decreases from 0.04% to 0.08% less than these value of the summer period.
社団法人日本航海学会の論文
1979-09-15