A study of several nights of IGY all‐sky camera data has indicated that auroras occur simultaneously in geomagnetically conjugate areas. The conjugate auroras are highly correlated in their variations of luminosity and show striking similarities in form and motion.
The Sq variation at geomagnetically conjugate areas is examined by use of the San Juan‐Trelew pair. It is shown that there is no particular similarity of the Sq variation at the two stations and that the northern and southern foci of the Sq current system are not geomagnetically conjugated. Three important causes of the asymmetric Sq variations are discussed. The asymmetric part of the solenoidal component of the dynamo current could be an immediate cause. The coupling of the northern and southern ionospheres by the geomagnetic field lines tends to exaggerate the effect of the difference in the induced polarization field, rather than to reduce it; further, because of the global scale of our system the inductance of our circuit may play an important role in skewing the Sq variations. Such a dissimilarity of the Sq variation at the conjugate points is in contrast to a striking similarity of polar magnetic storms at the conjugate points in the northern and southern auroral zones. The dynamo theory of polar magnetic storms is criticized on this basis.
A space‐time association between a widespread auroral glow over Alaska and X rays at balloon altitude on March 5, 1962, has been observed. It is estimated that electrons above 25 kev contribute about 1 per cent of the luminous excitation on this occasion.
The transient growth of an induced electric field is examined on the assumption that a primary electric field has been impressed along a band of aurorally enhanced conductivity in the ionosphere. The time contant for the growth is shown to be unimportant compared with the time scale of the auroral substorm, and the possibility that a certain class of auroral motions can be attributed to such a secondary or polarization electric field is discussed.
Recordings have been made of the 20 Mc/s signal strength of the satellite 1958δ2. A spaced‐receiver technique for measuring the heights of the irregularities responsible for the violent scintillations observed in these signals gives evidence that their altitudes ranged as high as 1000 km. A method for determining the height distribution of these irregularities, based on the amount of scintillation recorded when the satellite was at different altitudes, shows that they occurred mostly below 650 km and that occurrences at greater heights were sporadic.
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