Cleft signature in proton fluxes above 100 keV

Experimental evidence is presented that above 100 keV proton fluxes precipitating at high latitudes on the dayside constitute the high energy tail of the low energy proton population signaturing the polar cleft region. The precipitation zone of these higher energy protons covers the same latitude band as the low energy particles, and also experiences the same latitudinal displacements during changes in the geomagnetic conditions. The precipitation has an isotropic pitch angle distribution and the measured higher energy intensities compare favorably with values extrapolated from the spectrum at lower energies. The statistical invariant latitude pattern described by these above 100 keV precipitating protons in the magnetic local time span 06-18 hours is presented.