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dc.contributor.authorConnors, Martin
dc.identifier.other2007 American Geophysical Union (AGU) Meeting in San Francisco, CA, December 10-15, 2007
dc.descriptionAs noted in the application, I was also a co-author on several other presentations. The most influential of these was Donovan et al., given orally in the THEMIS session. My own presentation was in the poster session, and thus would be classified as having lesser impact (although 80% of the presentations at this huge (15,000 registrants) conference are posters). Several visitors did come to the poster. Japanese visitors invariably react positively to the fact that well-known senior Japanese scientist Kanji Hayashi is still active and collaborating. Our present main Japanese collaborators were represented by Kaori Sakaguchi and a useful discussion was had about proton aurora. Co-author Christopher Russell from UCLA visited the poster while I was not there and his graduate student will start to work on this event. Collaborator on other projects, Bob McPherron of UCLA, was interested in the subauroral sites mentioned in the poster and we discussed the substorm current wedge that was the main topic. We have followed up on this since and he may be added as a co-author on an article if he agrees sufficiently with our findings. McPherron’s theory of substorms may be contradicted by evidence presented in the poster – thus an interesting exchange of ideas has taken place. This is in the true spirit of scientific investigation. Unfortunately, the poster also drew the attention of Ian Mann of the University of Alberta. This is the only institution in the –world- with which we have a strained relationship. Mann’s comments, which generally had little to do with the poster, are now the subject of follow-up actions yet to be determined. The immediate future work from this poster is an attempt to meet a deadline for the important journal Geophysical Research Letters for its special issue on THEMIS. The immediate thrust has been to implement the IGRF and T89C magnetic models to enable better field-line tracing of the sort presented near the end of the poster. This will allow answering important questions about the mapping of auroras into the magnetosphere by comparing observations on the ground with those at the THEMIS spacecraft in a quantitative way. There have been programming challenges in doing this and it is taking longer than expected. Nevertheless it is still hoped to meet the GRL January 15 deadline. There will also be a special issue of the Journal of Geophysical Research, equally distinguished but with a longer article format, which will allow a more detailed discussion. Donovan will also write up optical results about this event for the two journals, and Igor Voronkov (now working with us at Athabasca University) is writing an article about the theory behind the observations for the GRL special issue. I also attended the THEMIS breakout session on Saturday, Dec. 15 at University of California, Berkeley, am invited to visit UCLA in January for further discussions and work, and expect to attend the next THEMIS Science Team meeting in California in April. Thus, showing the flag and the fact that we are doing meaningful work in support of THEMIS has been a valuable activity, and this poster (part of an evolutionary development in presenting THEMIS-related work) has been an important part of the activity allowing us to participate in THEMIS. Please download PDF file from
dc.description.abstractOver the past several years, intensive efforts have resulted in a significant improvement in the ground instrumentation for auroral studies in North America. A major part of this is due to the THEMIS ground program, both in the U.S. and in Canada. The THEMIS Ground-Based Observatory network has fielded 10 additional magnetometers in Canada and Alaska. Further THEMIS magnetometers are part of the GEONS outreach effort, found in the continental U.S. and Alaska. Athabasca University initiatives and collaborations have made yet further magnetometer data available, most notably from a new network of instruments in central Alberta. Several stations of the University of Tokyo STEP network remain operational, and some have been upgraded. There is finally a dense enough set of magnetic data that techniques based on forward modeling, and most relevant to the opportunity afforded by THEMIS, Automated Regional Modeling (ARM), can be reliably used. These techniques specify where net field-aligned current (FAC) and ionospheric electric current flow are located. In some cases the Pedersen system can also be included based on data. Even when it is not, it can be considered collocated with electrojet locations given by ARM. The extension into space of the FAC (net or Pedersen) allows comparison with the perturbations observed at THEMIS. We present results from an event on March 13, 2007, during which THEMIS in its early orbital configuration was over central North America, clear weather prevailed, and a substorm took place whose perturbations were ideally suited for inversion using ARM. At about 5 UT, activations were detected from the ground with magnetic perturbations also detected from THEMIS above the affected stations. The ground perturbations are very well represented by a three-dimensional substorm current wedge (SCW) system, and perturbations in space indicate radial propagation at a time when the electrojet was expanding poleward. Little longitudinal propagation of the SCW is suggested by the ground data.en
dc.description.sponsorshipAcademic & Professional Development Fund (A&PDF)en
dc.titlee Evolution of the Substorm Current Wedge from Ground and Space-based Magnetic Fieldsen

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