Response of ionospheric convection to changes in the interplanetary magnetic field: Lessons from a MHD simulation

Maynard, N. C.; Siscoe, G. L.; Sonnerup, B. U. Ö.; White, W. W.; Siebert, K. D.; Weimer, D. R.; Erickson, G. M.; Schoendorf, J.; Ober, D. M.; Wilson, G. R.

doi:10.1029/2000ja000454

Cited by 22 publications

(54 citation statements)

References 40 publications

(10 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The newly opened field lines on the backside of the X-line connect to the opposite hemisphere cusp. As a result, the small convection cell is in fact driven from merging in the opposite hemisphere (Maynard et al, 2001b(Maynard et al, , 2001c. Also the open boundary layer may be quite thick back along the flank of the magnetopause (Maynard et al, 2001a).…”

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Coupling the Solar-Wind/IMF to the Ionosphere Through the High Latitude CUSPS

Maynard¹

2005

Surv Geophys

View full text Add to dashboard Cite

Magnetic merging is a primary means for coupling energy from the solar wind into the magnetosphere-ionosphere system. The location and nature of the process remain as open questions. By correlating measurements from diverse locations and using large-scale MHD models to put the measurements in context, it is possible to constrain our interpretations of the global and meso-scale dynamics of magnetic merging. Recent evidence demonstrates that merging often occurs at high latitudes in the vicinity of the cusps. The location is in part controlled by the clock angle in the interplanetary magnetic field (IMF) Y-Z plane. In fact, B Y bifurcates the cusp relative to source regions. The newly opened field lines may couple to the ionosphere at MLT locations of as much as 3 hr away from local noon. On the other side of noon the cusp may be connected to merging sites in the opposite hemisphere. In fact, the small convection cell is generally driven by opposite hemisphere merging. B X controls the timing of the interaction and merging sites in each hemisphere, which may respond to planar features in the IMF at different times. Correlation times are variable and are controlled by the dynamics of the tilt of the interplanetary electric field phase plane. The orientation of the phase plane may change significantly on time scales of tens of minutes. Merging is temporally variable and may be occurring at multiple sites simultaneously. Accelerated electrons from the merging process excite optical signatures at the foot of the newly opened field lines. All-sky photometer observations of 557.7 nm emissions in the cusp region provide a ''television picture'' of the merging process and may be used to infer the temporal and spatial variability of merging, tied to variations in the IMF.

show abstract

Section: Discussionmentioning

confidence: 98%

“…Note that the all-sky image is inverted from the potential pattern, with both shown in their most commonly displayed orientation. (see text) (from Maynard et al, 2001bMaynard et al, , 2002. Figure 1 represent surfaces of constant IEF phase.…”

Section: A New Perspective On Solar Wind Coupling To the Magnetospherementioning

confidence: 98%

Coupling the Solar-Wind/IMF to the Ionosphere Through the High Latitude CUSPS

Maynard¹

2005

Surv Geophys

View full text Add to dashboard Cite

show abstract

“…17) show a poleward displacement of the merging region across noon. Maynard et al (2001b) found that because of tilted phase planes, the two hemispheres can respond to the same IMF signal at very different times. Weimer et al (2002) found that the tilt of these phase planes could change significantly on scales of tens of minutes.…”

Section: Implications Relative To the Source Electronsmentioning

confidence: 99%

“…Maynard et al, 2001aMaynard et al, , 2001bMaynard et al, , 2003aMaynard et al, , 2003b. The "sash", a low magnetic field region draped on the magnetopause which generally follows the anti-parallel merging locations of Crooker (1979) and Luhmann et al (1984), was first identified in the MHD simulations (White et al, 1998 and then observed in a multi-satellite study by Maynard et al (2001a).…”

Section: Imf and Dipole Tilt Control Of Merging Locationsmentioning

confidence: 99%

Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images

Maynard¹,

Moen

Burke

et al. 2004

Ann. Geophys.

Self Cite

View full text Add to dashboard Cite

Abstract. 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-Ålesund on 19 December 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 557.7 nm emissions in the cusp. Polar observations at the magnetopause have directly linked enhanced fluxes of ≥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 ∼150 • structured 557.7-nm emissions came from east of the 13:00 MLT meridian. At larger clock angles the emissions appeared between 12:00 and 13:00 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, Correspondence to: N. C. Maynard (nmaynard@mrcnh.com) 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.

show abstract

“…The simulations show that the interaction with the magnetosphere is a mixture of convection driven through the LLBL on closed field lines and convection that is merging driven via an open polar cap. In the actual case, the B Y reversal should shift the merging site to the postnoon local time sector and introduce a pause in merging during the transition [see Maynard et al, 2001a].…”

Section: Hydrodynamic and Magnetohydrodynamic Coupling To The Magnetomentioning

confidence: 99%

Interactions of the heliospheric current and plasma sheets with the bow shock: Cluster and Polar observations in the magnetosheath

et al. 2011

View full text Add to dashboard Cite

[1] On 12 March 2001, the Polar and Cluster spacecraft were at subsolar and cusp latitudes in the dayside magnetosheath, respectively, where they monitored the passage by Earth of a large-scale planar structure containing the high-density heliospheric plasma sheet (HPS) and the embedded current sheet. Over significant intervals, as the magnetic hole of the HPS passed Cluster and Polar, magnetic field strengths |B| were much smaller than expected for the shocked interplanetary magnetic field. For short periods, |B| even fell below values measured by ACE in the upstream solar wind. Within the magnetic hole the ratio of plasma thermal and magnetic pressures (plasma b) was consistently >100 and exceeded 1000. A temporary increase in lag times for identifiable features in B components to propagate from the location of ACE to those of Cluster and Polar was associated with the expansion (and subsequent compression) of the magnetic field and observed low |B|. Triangulation of the propagation velocity of these features across the four Cluster spacecraft configuration showed consistency with the measured component of ion velocity normal to the large-scale planar structure. B experienced large-amplitude wave activity, including fast magnetosonic waves. Within the low |B| region, guiding center behavior was disrupted and ions were subject to hydrodynamic rather than magnetohydrodynamic forcing. Under the reported conditions, a significant portion of the interplanetary coupling to the magnetosphere should proceed through interaction with the low-latitude boundary layer. Data acquired during a nearly simultaneous high-latitude pass of a Defense Meteorological Satellites Program satellite are consistent with this conjecture.

show abstract

Response of ionospheric convection to changes in the interplanetary magnetic field: Lessons from a MHD simulation

Cited by 22 publications

References 40 publications

Coupling the Solar-Wind/IMF to the Ionosphere Through the High Latitude CUSPS

Coupling the Solar-Wind/IMF to the Ionosphere Through the High Latitude CUSPS

Temporal-spatial structure of magnetic merging at the magnetopause inferred from 557.7-nm all-sky images

Interactions of the heliospheric current and plasma sheets with the bow shock: Cluster and Polar observations in the magnetosheath

Contact Info

Product

Resources

About