Kleckner, E. W.

Smith, L. L.

Wildman, P. J. L.

UNT Digital Library

' - JJfl/wL -517-37?7 (;AJf~ 7,l/dltJ3- --.:1 THE RELATIONSHIP OF STABLE AURORAL RED ARCS TO THE PLASMAPAUSE E. W. Kleckner and L. L. Smith Battelle Memorial Institute Pacific Northwest Laboratories P. 0. Box 999 RichLand, Washington 99352 and P. J. L. Wildman Air Force Cambridge Research Laboratories Laurence G. Hanscom Field Bedford, Massachusetts 01730 ,--------N 0 TIC E --------, Thb repvrt wae prepan~rl as an account of \:ork sponsored by the United States Government. Netther the United Stal~o:s 1lOf the United Statts Atom ic Energy Commission nor any of their employees, nor any of their contra~tors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liabilit y or responsibility for the accuracy, com-pleteness o r usefulness of any information, app~ratus, product or process disclosed, or re~resems that 1ts use would not infringe privately own ed nghts. For Presentation At AMERICAN GEOPHYSICAL UNION ANNUAL FALL MEETING December 12-17, 1974 San Francisco, California ! Ua Ll 1 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. " THE RELATIONSHIP OF STABLE AURORAL RED ARCS TO THE PLASMAPAUSE On the question of cold plasma dynamics, even the most basic correlation--that of the relationship between the. plasmapause at high altitudes and the light ion trough in the ionosphere at low altitudes--is subject to considerable controversy. At low altitudes there is a drop in the total F region ionization beginning between L=2 and L=3 and forming a trough located at L=4. At high altitudes the plasmapause··,~·· signature is characterized by an abrupt density discontinuity near L=4. In order to relate these boundaries physically, one must ascertain the distribution of ionization along the magnetic field line between the ionosphere and the outer magnetosphere. The light-ion trough and the plasmapause are subject to changes in position and steepness as the I magnetic activity varies. The relationship between the plasmapause and I the light-ion trough offers a potential tie between the low-and-high . . altitude magnetosphere if the plasma distribution along the field lines between L=2-to-6 region can be measur~!) ~·gain some insight into this question we have examined data ) from several simultaneous satellite-ground based measurements of ion density and plasmapause positi~ Specifically, the magnetic storms of September 26/27 .and April 21/22 of 1971 were studied using ISIS-I data and the ground based photometric data on SAR-Arc position and intensity from BNW Observatory. Both storms were similar in intensity (DST = -90y) and the SAR-Arcs occurred at the same time into the recovery phase .p.• -2-(=-5 hours). The ISIS observations were simultaneous with the ground observations and within one hour of local time. The September event, however, was preceded by a smaller storm 24 ·hours earlier. It is well established that the pos1tion of the SAR-Arc marks the location of ' plasmapause in the outer magnetosphere. The light-ion trough of April has its equatorward edge coincident with the SAR-Arc position at an invariant latitude of 54°, thus indicating the commonality of these features. By contrast, the September event is characterized by a complex structure in the light-ion trough. If again the SAR-Arc marks·the plasmapause position, then its coincidence with the poleward edge of the equatorward boundary of the trough has several implications. There were no multiple arcs on the night in question. The most likely inter-pretation of the trough structure is that the ragged density profile is . ·-- . a result of density depletion due to incomplete p.lasmasphere filling fol-lowing the September 25 storm. That is to say, during the recovery phase of the September 25 storm, upward flows of cold plasma from the ionosphere to the plasmasphere occurred (at an .invariant latitude ot· =50°). The subsequent storm of September 26 then compressed the plasmasphere, and the SAR-Arc occurred at the poleward edge of the trough even though there were internal density discontinuities in the plasmasphere. As a follow-up on the storm, note that the plasmasphere is eroded as far as the inner density gradient before gradual filling restores the quiet-time configuration. 

Relationship of stable auroral red arcs to the plasmapause

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Relationship of stable auroral red arcs to the plasmapause

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