Proton temperatures in the ring current from ENA images and in situ measurements X.X. Zhang, J. D. Perez, T. Chen, C. Wang, P.C. Brandt, D.G. Mitchell, and Y.L. Wang Ion equatorial flux distributions, inverted from energetic neutral atom (ENA) images in different energy channels obtained by the HENA imager on the IMAGE satellite, are used to deduce the plasma ion temperature in the ring current. During the early period of the recovery phase of the strong storm on 12 August 2000, the deduced ion temperatures of the ring current are consistent with the values inferred from in situ LANL MPA measurements. The ion temperatures show a peak in the post-midnight/pre-dawn sector coincident with the peak in the equatorial ion distributions. The temperature, however, is more symmetrical than the ion flux implying that, at least in this part of the energy spectrum, the density variations make the major contribution to pressure gradients. _______________ Geophysical Research Letters, 32, L16101, doi:10.1029/2005GL023481.