  The acceleration of charged particles by interplanetary shocks can drain a
non-negligible fraction of the upstream ram pressure. For a sample of shocks
observed in-situ at 1 AU by the ACE and Wind spacecraft, time-series of the
non-Maxwellian components (supra-thermal and higher-energy) of the ion and
electron energy spectra were acquired for each event. These were averaged for
one hour before and after the time of the shock passage to determine their
partial pressure. Using the MHD Rankine-Hugoniot jump conditions, we find that
the fraction of the total upstream energy flux transferred to non-Maxwellian
downstream particles is typically about 2-16%. Notably, our sample shows that
neither the fast magnetosonic Mach number nor the angle between the shock
normal and average upstream magnetic field are correlated with non-Maxwellian
particle pressure.
