  THEMIS multi-point observation of the plasma and magnetic fields, conducted
simultaneously in the dayside magnetosheath and magnetosphere, were used to
collect 646 large-scale magnetosheath plasma jets interacting with the
magnetopause. The jets were identified as dense and fast streams of the
magnetosheath plasma whose energy density is higher than that of the upstream
solar wind. The jet interaction with the magnetopause was revealed from sudden
inward motion of the magnetopause and an enhancement in the geomagnetic field.
The penetration was determined as appearance of the magnetosheath plasma
against the background of the hot magnetospheric particle population. We found
that almost 60% of the jets penetrated through the magnetopause. Vast majority
of the penetrating jets was characterized by high velocities V > 220 km/s and
kinetic bk > 1 that corresponded to a combination of finite Larmor radius
effect with a mechanisms of impulsive penetration. The average plasma flux in
the penetrating jets was found to be 1.5 times larger than the average plasma
flux of the solar wind. The average rate of jet-related penetration of the
magnetosheath plasma into the dayside magnetosphere was estimated to be ~10^29
particles per day. The rate varies highly with time and can achieve values of
1.5*10^29 particles per hour that is comparable with estimates of the total
amount of plasma entering the dayside magnetosphere.
