MMS observations of heavy ion heating in a dayside reconnection exhaust

On 2015-09-20, the Magnetospheric Multiscale (MMS) mission crossed the dusk magnetopause during a CME-driven storm. This storm was preceded by and resulted in further substorm activity. Enhanced densities and fluxes of both cold (10s of eV) and hotter (10s of keV) magnetospheric and magnetosheath heavy ion species were observed reaching the magnetopause. We present the evolution of the velocity distributions for H+, He+, He++, and O+ measured by the Hot Plasma Composition Analyzer (HPCA) on MMS during this magnetopause crossing. The heating of individual ion species across a reconnection exhaust is analyzed to determine how heavy ions flowing into the reconnection site may be affected compared to the proton-dominated magnetosheath bulk population.