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Millstone Radar Observations of the Mid-Latitude Ionosphere - Nov 93 Event

Elevation scans in the N-S meridional plane made with the Millstone Hill incoherent scatter radar to support the Russian/American Tomography Experiment campaign were made in the pre-midnight sector each evening during the November 3-6, 1993 period. This interval had been pre-selected for an investigation of the disturbed ionosphere based on recurrent solar-induced activity. The large magnetospheric compression and storm intensification which characterized this event (selected as a special-study interval for the National Space Weather Project) occurred shortly after operations began on the night of November 3-4, 1993. A snapshot of the ionospheric configuration at 00:30 UT on Nov 4, 1993 is shown on the left (below) which combines the radar latitude/altitude scan depicting F-region ionospheric densities with particle-flux and drift meter data from a simultaneous DMSP F8 overflight. Ionization produced by particle precipitation is seen near 60 deg magnetic latitude (45 deg geodetic) whle, equatorward of the precipitation, the F layer has been uplifted. The Millstone Hill meridian was at ~19 MLT at the time of storm intensification.

Data Figures for Nov 93 Campaign

Millstone RATE Observations

At the right (above) the radar elevation-scan data have been displayed as functions of latitude and time through the storm onset at altitudes in the F-1 region (where precipitation effects are most evident) and near the F peak altitude. Density enhancements in response to storm-induced precipitation are seen extending equatorward to near 40 deg geodetic latitude (55 deg Invariant latitude) after 00 UT on 4 Nov 93.

A final figure displays the radar density data as the temporal evolution of the density/altitude profile at separate latitudes between 38 deg (lower right) and 48 deg (upper left) geodetic latitude. The prompt uplifting of the ionospheric F region at latitudes equatorward of 45 deg is clearly seen as are the effects of the intense particle precipitation which began near 01:00 UT on 4 Nov 93. The uplift of the F Region is attributed to an intense eastward-directed electric field imposed in the mid and low-latitude ionosphere/magnetosphere system during the large compression of the magnetospheric cavity which accompanied the 23:20 UT (3 Nov 93) arrival of the solar-wind NCDE. A similar event occurred during the March 20, 1990 storm onset. Formation of Low-Latitude Trough during Major Storm Onset (gif format)

Foster, J. C., M. J. Buonsanto, J. M. Holt, J. A. Klobuchar, P. Fougere, W. Pakula, T. D. Raymund, V. E. Kunitsyn, E. S. Andreeva, E. D. Tereshchenko, and B. Z. Khudukon, Russian-American Tomography Experiment, Int. J. Imaging Sys. Tech, 5, 148-159, 1994. [ RATE ionospheric reconstruction with Millstone Hill Radar elevation scan.]

http://www.haystack.edu/~jcf/research/nov93.htm -- Revised: June 27, 1997
E-mail: jcf@hyperion.haystack.edu