A comparison of neutral atom detector unit neutral atom image inversion with a comprehensive ring current model

Abstract

We present energetic neutral atom (ENA) images in the energy range 45 to 50 keV for H and 92 to 138 keV for O measured by the Neutral Atom Detector Unit (NUADU) onboard Double Star TC-2 during a geomagnetic storm on 8 May 2005. We compare the ion fluxes deduced from inversion of the NUADU image with those calculated using the Comprehensive Ring Current Model (CRCM). This comparison shows that the two approaches are consistent when used to derive the configuration of the corresponding global ion distribution and the peak ion fluxes. The deduced peak ion flux is located in the premidnight sector at 1540 UT, while the deduced ion peak flux is located in the midnight sector at 1610 UT. There are strong ion fluxes in the region between L = 2 and 1 = 4 which form a closed loop configuration. The ion peak flux is about 2.2 × 10 6/cm2/sr/ keV/s. The deduced ion distribution agrees well with the NUADU measurement. The agreement between the inverted ion distributions and the CRCM results give us confidence in applying our ENA imaging and modeling techniques to the study of the evolution of the inner magnetosphere plasma distribution and the global dynamics of the ring current during magnetic storms. Copyright 2008 by the American Geophysical Union.