Based on the experiments we consider, we predict that the s/1 variations of Pseed will be found to be similar to those of PEF•, and largely to explain them. Finally, we find reasons, based on the similarity of the DRSF variations to s/1 patterns of the average scintillation index, for not using, as is commonly done, such scintillation patterns as substitutes for PEF• or Pinst patterns.

A preliminary study of the vertical and north-south horizontal ion motions in plasma bubbles in the near-equatorial ionosphere utilizing drift meter data from Atmosphere Explorer E is presented. High-resolution data show that the vertical ion velocity in some bubbles increases approximately linearly with (N0-N)/N, where No is the background ion concentration and N is the bubble ion concentration. At sufficiently large No/N the vertical ion velocity saturates, but often at a value substantially larger than the ratio of the gravitational acceleration to the ion neutral collision frequency (g/Vin), which is the nominal collision-dominated velocity limit for cylindrical bubbles. These larger than nominal velocities may result from background eastward electric fields and/or from a vertically elongated bubble cross section. The unanticipated observation that large poleward horizontal drifts accompany these vertical drifts seems to follow naturally from a redistribution of plasma along flux tubes as the plasma convects from the bottomside of the F region to high altitudes. 137https://ntrs.nasa.gov/search.jsp?R=19860019839 2018-05-10T23:07:46+00:00Z

No abstract

We have reexamined incoherent scatter radar data on electron and ion temperature from the Jicamarca Radar Observatory (12°S, 77°W; 1°N diplat) for the period 1967‐68 and early 1969. We find clear evidence of systematic nighttime temperature increases presumably associated with the “midnight pressure bulge” and the collapse of the middle latitude F region. A significant new finding is that the temperature enhancements tend on the average to occur about two hours before midnight in the local summer and about one hour after midnight in the local winter. The bulges appear in various shapes and the enhancement magnitudes vary considerably from barely detectable to many tens of degrees Kelvin, but show a definite tendency to be smaller in winter than in summer, when increases of up to 200 K are sometimes observed. Changeover from “summer” to “winter” behavior occurs within two months or less around equinox. Our results are consistent with the hypothesis of a nighttime equatorial temperature bulge moving with the antisolar meridian, but, at Jicamarca, systematically centered ∼ 30° west of this meridian ( ∼ 2 hrs before midnight) near the December solstice and ∼ 15° east of it near the June solstice. Our data have relevance to the questions of seasonal changes in the phase and amplitude of the tidal modes responsible for the midnight pressure and temperature bulge.

Some results of "dispersion" analysis of F-region drift data obtained at Ibadan (dip 6S) are presented. On a number of occasions marked dispersion involving a velocity variation of about 60 msec-1 or more from low to high fading frequencies has been found. The results suggest that in the "correlation" analysis the "apparent" velocity probably measures the motion better than the "true" velocity, whether or not dispersion is present. It is also found that the motions occurring at this latitude are not always in the east-west direction. Occasionally, two independent motions corresponding to different fading frequency ranges and moving at right angles to each other may be involved.