A Discussion of Arctic Ionograms
AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA
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Example of arctic ionogram sequences, recorded on the AFCRL Flying Ionospheric Laboratory, are presented. The purpose of this paper is to show that a ionogram sequences, recorded on arctic flights, facilitate the interpretation of oblique incidence echoes from E-and F-layer heights, b parameters of the arctic ionosphere can be mapped by using the auroral oval as an ordering system, c vertical and oblique incidence echoes, appearing on ground station ionograms, can be interpreted in terms of the stations position relative to the auroral oval. The analysis of a three hour flight with 6 latitudinal scans underneath an auroral band shows the close relationship between auroral sporadic E echoes Esa and discrete aurora. The investigation of 49 latitudinal scans through the auroral oval during times of low magnetic activity revealed the existence of a particle produced E layer which is oval aligned, is 2 deg to 6 deg wide in corrected geomagnetic latitude and occurs at all corrected geomagnetic times. This layer produces the night E echoes. A new ionogram analysis procedure, which uses oblique incidence F-layer echoes, is demonstrated, and the feasibility of monitoring the latitude of the southern edge of the polar F-layer irregularity zone by using this new analysis procedure is demonstrated.
- Atmospheric Physics