Temporal/spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images <p> HR: <span class="hr"> 09:45h<br></span> AN: <span class="an"> SM51A-08 <a href="../absbook/fm03-SM51A.pdf">[PDF]</a><br></span> TI: <span class="ti"> Temporal/spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images <br></span> AU: <span class="au"> * Maynard, N C<br></span> EM: <span class="em"> nmaynard@mrcnh.com<br></span> AF: <span class="af"> Mission Research Corporation, 589 West Hollis Street; Suite 201, Nashua, NH 03062 United States<br></span> AU: <span class="au"> Moen, J <br></span> AF: <span class="af"> University of Oslo, Deparment of Physics, Oslo, N-0316 Norway <br></span> AU: <span class="au"> Burke, W J<br></span> AF: <span class="af"> Air Force Research Laboratory, 29 Randolph Road, Hanscom AFB, MA 01731 United States<br></span> AU: <span class="au"> Lester, M <br></span> AF: <span class="af"> University of Leicester, Deparment of Physics, Leicester, LE1 7RH United Kingdom <br></span> AU: <span class="au"> Ober, D M<br></span> AF: <span class="af"> Mission Research Corporation, 589 West Hollis Street; Suite 201, Nashua, NH 03062 United States<br></span> AU: <span class="au"> Scudder, J D<br></span> AF: <span class="af"> University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States<br></span> AU: <span class="au"> Siebert, K D<br></span> AF: <span class="af"> Mission Research Corporation, 589 West Hollis Street; Suite 201, Nashua, NH 03062 United States<br></span> AU: <span class="au"> Weimer, D R<br></span> AF: <span class="af"> Mission Research Corporation, 589 West Hollis Street; Suite 201, Nashua, NH 03062 United States<br></span> AU: <span class="au"> Russell, C T<br></span> AF: <span class="af"> University of California at Los Angeles, IGPP, Los Angeles, CA 90015 United States<br></span> AU: <span class="au"> Balogh, A <br></span> AF: <span class="af"> Imperial College, Exhibition Road, London, SW7 2BW United Kingdom <br></span> AB: <span class="ab"> We demonstrate that high-resolution 557.7 nm all-sky images are useful tools for investigating the spatial and temporal evolution of merging on the dayside magnetopause. Analysis of ground and satellite measurements leads us to conclude that high-latitude merging events can occur at multiple sites simultaneously and vary asynchronously on time scales of 30 s to 3 min. Variations of 557.7 nm emissions were observed at a 10 s cadence at Ny-{\AA}lesund on December 19, 2001 while significant changes in the IMF clock angle were reaching the magnetopause. The optical patterns are consistent with a scenario in which merging occurs around the rim of the high-latitude cusp at positions dictated by the IMF clock angle. Electrons energized at merging sites represent plausible sources for 557.7nm emissions in the cusp. Polar observations at the magnetopause have directly linked enhanced fluxes of ${\ge}$0.5 keV electrons with merging. Spectra of electrons responsible for some of the emissions, measured during a DMSP F15 overflight, exhibit ``inverted-V'' features indicating further acceleration above the ionosphere. SuperDARN spectral width boundaries, characteristic of open-closed field line transitions, are located at the equatorward edge of the 557.7-nm emissions. Optical data suggest that with IMF $B_Y > 0$, the Northern Hemisphere cusp divides into three source regions. When the IMF clock angle was $\sim$150$^{\circ}$ structured 557.7 nm emissions came from east of the 1300 MLT meridian. At larger clock angles the emissions appeared between 1200 and 1300 MLT. No significant 557.7 nm emissions were detected in the prenoon MLT sector. MHD simulations corroborate our scenario, showing that with the observed large dipole-tilt and IMF clock angles, merging sites develop near the front and eastern portions of the high-altitude cusp rim in the Northern Hemisphere and near the western part of the cusp rim in the Southern Hemisphere. <br></span> DE: <span class="de"> 2407 Auroral ionosphere (2704)<br></span> DE: <span class="de"> 2431 Ionosphere/magnetosphere interactions (2736)<br></span> DE: <span class="de"> 2736 Magnetosphere/ionosphere interactions<br></span> DE: <span class="de"> 2760 Plasma convection<br></span> DE: <span class="de"> 2784 Solar wind/magnetosphere interactions<br></span> SC: <span class="sc"> SPA - Magnetospheric Physics [SM]<br></span> MN: <span class="mn"> 2003 Fall Meeting<br></span></p></body></html>