[Aurora] University of Houston

Space Physics Group

Occurrence rate of Pc3 emissions during high latitude impulsive events: Preliminary estimates

E. A. Bering, III (Physics Department, University of Houston, Houston, TX 77204-5506), M. J. Engebretson (Physics Department, Augsburg College, 2211 Riverside Ave., Minneapolis, MN 55454), and R. L. Arnoldy (Physics Department, Science \& Engineering Res. Bldg., University of New Hampshire, Durham, New Hampshire 03824)

Abstract

The major subjects of this paper will be the possible signatures of magnetopause and magnetospheric boundary layer processes that are observed in the ionosphere and on the ground. It is well known that continuous spacecraft observations of the magnetopause are impossible. Thus, developing an understanding of how to observe boundary layer processes continuously from the ground is critical to achieving an understanding of long term time variations in boundary layer processes. This study will focus specifically on a search for simultaneous observations of two different geomagnetic perturbation phenomena whose possible sources may be either the magnetopause or the upstream solar wind. The perturbation phenomena that will be studied are Pc 3 micropulsations and high latitude impulsive events, which are also known as travelling convection vortices (TCV's). The possible physical connection between some TCV's and Pc 3 pulsations has not been addressed in the literature. In recent papers, the authors have observed a few cases of Pc 3 emissions that occurred simultaneously with TCV events. This work found that these PC 3's appeared to have the same horizontal speed as the TCV's. This observation suggests that these Pc 3's and TCV's were on the same field lines and may share a common source. However, at present, this observation is an isolated one. It is not clear if Pc 3's occur regularly with TCV's or not. This study will search existing data bases for further examples of simultaneous Pc 3 - TCV observations by starting with lists of Pc 3 bursts. The data bases that will be searched are the South Pole search coil magnetometer data, particularly during the period of the 1985-86 Balloon Campaign and the Magnetometer Array for Cusp and Cleft Studies (MACCS) data base. The results of this study will include a statistical estimate of the rate of occurrence of joint Pc 3 bursts and high latitude impulsive events. So we far we have found that at least 77% of the impulsive events that we have examined are associated with PC3 bursts or enhancments. The phase speed of the Pc 3's is roughly equal to the velocity of the associated TCV's, when known. The IMF orientation and amplitude dependence of the event ensemble will also be examined.

Text and Figures

The body of the text and the figures are in PerfectOffice Envoy® format. To read the paper, you need to have an Envoy® viewer. You may either download the paper and view it off line, or have the Envoy® viewer listed as a viewer for files of MIME type application/envoy with extension .evy in your browser's configuration file. If you don't have your own copy of Envoy®, there is Distributable Viewer version available online (free). Download the Envoy Viewer here. If your browser is Netscape 2.0 or higher, there is a Tumbleweed Envoy plug-in that can be downloaded here. Once you have the viewer set up the way you want it, you are ready to download or view the paper.

Figures Alone, In GIF or JPEG

  1. Figure 1
  2. Figure 2
  3. Figure 3
  4. Figure 4
  5. Figure 5
  6. Figure 6
  7. Figure 7
  8. Figure 8
  9. Figure 9
  10. Figure 10
  11. Figure 11
  12. Figure 12
  13. Figure 13
  14. Figure 14
  15. Figure 15
  16. Figure 16
  17. Figure 17
  18. Figure 18
  19. Figure 19
  20. Figure 20
  21. Figure 21
  22. Figure 22
  23. Figure 23
  24. Figure 24






At this point, you are free to return to the Snowmass poster page. You can also go to the UH Space Physics Group Current Activities description, UH Space Physics Group Web Site, the beginning of my personal Home Page or the midst of my vita. Questions about the data or possible collaborative papers may be addressed to me at <eabering@uh.edu>.