Electron density structures in the polar F region. (Reannouncement with new availability information)
Technical Report
·
OSTI ID:177488
Arctic campaigns conducted over the last decade, using digital Ionospheric sounders and all-sky imaging photometers have allowed an ordering of the typically very irregular behavior of the polar cap ionosphere, and a preliminary definition of the solar cycle effects. Under quiet magnetic conditions the polar cap is populated with sun-aligned F layer arcs. Under magnetically active conditions (Bz<0) large patches of enhanced plasma densities move rapidly from the cusp region across the polar cap. Both arcs and patches are highly structured. NmF2 enhancements up to a factor of ten above the background are observed In patches, while density enhancements In arcs are a factor of two to three. Summer and winter ionospheric soundings in the central polar cap (Qaanaaq, Greenland, 87 deg CG Latitude) under various solar cycle conditions, establish the observed pattern as a start for the systematic modeling of this most turbulent region. The general occurrence of patches is controlled by the sign of the IMF Bz component; patches occur typically when Bz < 0. The sub-cusp solar produced ionosphere had previously been identified as the potential source region of the patch plasma. At solar minimum IONCAP foF2 model results for 730 CGL on the magnetic noon meridian (postulated source region) provide an envelope for the observed maximum patch densities. For solar maximum conditions, the source region is likely at times at lower latitudes (< 65 deg CGL). 1982 through 1989 observations show a direct dependence of the patch maximum foF2 values on sunspot number.
- Research Organization:
- Phillips Lab., Hanscom AFB, MA (United States)
- OSTI ID:
- 177488
- Report Number(s):
- AD-A--257203/0/XAB; PL-TR--92-2247
- Country of Publication:
- United States
- Language:
- English
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