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Oxygen‐hydrogen differentiated observations from TWINS: The 22 July 2009 storm
Author(s) -
Valek P. W.,
Goldstein J.,
McComas D. J.,
Ilie R.,
Buzulukova N.,
Fok M.C.,
Perez J. D.
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/jgra.50204
Subject(s) - storm , altitude (triangle) , magnetosphere , atmospheric sciences , physics , range (aeronautics) , hydrogen , environmental science , geomagnetic storm , oxygen , astrophysics , meteorology , materials science , nuclear physics , plasma , solar wind , mathematics , geometry , quantum mechanics , composite material
The 22 July 2009 magnetic storm is the first significant storm during the emergence of the recent prolonged solar cycle minimum. This moderate storm (minimum Dst approximately ≤ −78 nT) has received a good deal of attention in the community. We present here global observations of the H and O populations in the inner magnetosphere using Energetic Neutral Atom (ENA) observations from the TWINS mission. We develop and provide the methodology for separating H and O ENAs, based on mass dependent differences in the pulse height distributions of the microchannel plate (MCP) based detectors. We present the first composition separated H and O ENA images at central energies of 16 and 32 keV. We also show that TWINS has sufficient angular resolution to separate the High Altitude Emissions (HAEs) from the Low Altitude Emissions (LAEs). We observe that all ENA emissions in this energy range quickly rise, but the O ENAs have a larger relative increase, and stay at elevated levels much longer, well into the recovery phase.