Evolution of CIR storm on 22 July 2009

Global images of ion intensities are deconvolved from TWINS ENA images during the main and recovery phase of a CIR storm on 22 July 2009. The global spatial ion images taken at different times, along with solar wind data, geomagnetic activity indices, geosynchronous orbit observations, and in situ measurements from the THEMIS mission provide a picture of the evolution of the ring current during both the main phase and early recovery phase of the storm. Major features of the evolution are consistent with expectations based upon time dependent geomagnetic indices, e.g., SYM/H and ASY/H, and geosynchronous orbit detection of dipolarizations from GOES 11 and 12. Direct comparisons are made with in situ THEMIS ESA and SST spectral measurements. The peak energy of the ion spectrum in the ring current is seen to decrease in the recovery phase. The time evolution of the ion energy spectra over the range from 2.5 to 97.5 keV at the spatial peaks of the ring current in the inner magnetosphere obtained from ENA images is presented for the first time.