Oxygen‐hydrogen differentiated observations from TWINS: The 22 July 2009 storm. Issue 6 (25th June 2013)

• Record Type: Journal Article
• Authors: Valek, P. W.; Goldstein, J.; McComas, D. J.; Ilie, R.; Buzulukova, N.; Fok, M.‐C.; Perez, J. D.
• Is Part Of: Journal of geophysical research. Volume 118:Issue 6(2013:Jun.)
• Page Start: 3377
• Page End: 3393
• Publication Date: 2013-06-25
• Subjects: magnetic storms -- ENAs -- Oxygen -- TWINS; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/jgra.50204
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract : [1] 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. Key Points: We present the first 16 and 32 keV global O and H ENA images Sufficient spatial resolution to differentiate between H and O HAEs and LAEs We identified key differences in the evolution of H and O during this storm