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Imaging magnetospheric boundaries at ionospheric heights
Author(s) -
Mendillo Michael,
Baumgardner Jeffrey,
Wroten Joei,
Martinis Carlos,
Smith Steven,
Merenda KevinDruis,
Fritz Theodore,
Hairston Marc,
Heelis Rod,
Barbieri Cesare
Publication year - 2013
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019267
Subject(s) - magnetosphere , plasmasphere , ring current , defense meteorological satellite program , ionosphere , thermosphere , geophysics , geomagnetic storm , zenith , physics , earth's magnetic field , geology , airglow , field line , atmospheric sciences , geodesy , magnetic field , quantum mechanics
An all‐sky imager (ASI) records atmospheric emissions from zenith to low on the horizon at all azimuths, a region typically spanning millions of square kilometers. Each pixel (with its unique elevation, azimuth, and emission height) can be mapped along B‐field lines to the equatorial plane of the magnetosphere. Auroral and subauroral structures and boundaries seen in emission within the ionosphere‐thermosphere (I‐T) system can thus be related to source regions. For a midlatitude site, this I‐T to inner magnetosphere connection typically falls within the L = 2–5 earth radii domain. In this study, we present the first case of a stable auroral red (SAR) arc observed from three widely spaced ASI sites (Europe, North America, New Zealand). SAR arcs are produced during the main and recovery phases of a geomagnetic storm, with emission driven by heat conduction from a very specific location in the magnetosphere—the L value where the plasmapause and the inner edge of the ring current overlap. Using three‐site observations, we show that this boundary can be followed for 24 consecutive hours. Simultaneous observations made by three satellites in the Defense Meteorological Satellite Program (DMSP) show that the lowest latitude peak in electron temperature can be used to map the same boundary. A key structure of the inner magnetosphere that cannot be observed continuously from sensors orbiting within the magnetosphere is made continuously visible to ground‐based optical systems via effects caused by the drainage of small amounts of ring current energy into the I‐T system.