Structure and Movement of Es Detected by Loran Observations
1964 年 16 巻 2 号 p. 75-88
詳細
1964 年 16 巻 2 号 p. 75-88
A study is made of movements in the Es region by means of measurements of pulsed waves at 1.85Mc/s emitted from a Loran station and of ionospheric vertical soundings.
Moving clouds in the Es region of large lateral dimensions are usually observed during the night either isolated or grouped like the wavy clouds sometimes seen in the troposphere. The speed of about 80m/sec and the direction towards the southwest are deduced from various kinds of observations.
It is inferred from this experiment that the observed Es layer is of two types: the first is the horizontally stratified thin layer produced by electromagnetic re-distribution due to the laminar wind shear and the second consists of a number of elongated regions of excess ionization, being of the order of 100km long and 10km wide, which may be caused by hydrodynamical instability in the wind shear prevailing there.
