Effects on the distant geomagnetic tail of a fivefold density drop in the inner sheath region of a magnetic cloud: A joint Wind–ACE study
| Autor: | Per Even Sandholt, N. C. Maynard, Nikolai V. Erkaev, Roy B. Torbert, Charlie J. Farrugia, Helfried K. Biernat, K. W. Ogilvie, D. Langmayr, U. Taubenschuss, Ian G. Richardson, Adam Szabo |
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| Rok vydání: | 2009 |
| Předmět: |
Physics
Pressure drop Atmospheric Science Meteorology Ecliptic Aerospace Engineering Astronomy and Astrophysics Astrophysics Bow shocks in astrophysics Geophysics Earth's magnetic field Magnetosheath Space and Planetary Science Physics::Space Physics General Earth and Planetary Sciences Astrophysics::Earth and Planetary Astrophysics Magnetic cloud Magnetohydrodynamics Interplanetary spaceflight |
| Zdroj: | Advances in Space Research. 44:1288-1294 |
| ISSN: | 0273-1177 |
| DOI: | 10.1016/j.asr.2009.07.003 |
| Popis: | Using a serendipitous configuration of the ACE and Wind spacecraft, we monitor the response of the distant geomagnetic tail (∼ −220 R E ) to an abrupt, approx. fivefold pressure drop (from ∼19.0 to ∼3.5 nPa) at the front boundary of a magnetic cloud (MC) on November 20, 2003. The interplanetary data are from ACE in orbit around the L1 point. The far-tail observations are from Wind, which was nominally in the magnetosheath, separated from the Sun–Earth line by ∼ 40 R E . The magnetic field in the innermost sheath region of the MC had a large B y ( ∼ 30 nT ) and substantial and variable flows lateral to the Sun–Earth line. There was also a significant northward field (∼35 nT), unique in the vicinity of this MC. These extreme values are reached in a filament forming the earliest relic of material accreted by the MC en route to Earth. The effects resulting from these on the far geomagnetic tail are: (1) expansion, (2) tail twisting, and (3) tail tilting. These extreme conditions were in part responsible for a crossing by Wind of a neutral sheet which is tilted by ∼85° to the ecliptic. Further, Wind made two successive excursions deep into the geomagnetic tail, in the first of which a tailward flow burst of ∼1200 km/s was observed. The dayside part of the interaction of the sudden and large dynamic pressure drop with the bow shock is studied with a local 3D MHD simulation. This work is a contribution to the area ICME/MC-sheaths–magnetosheath interactions. |
| Databáze: | OpenAIRE |
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