ИСТИНА

THEMIS multi-point observation of the plasma and magnetic field, conducted simultaneously in the dayside magnetosheath and magnetosphere, were used to collect several 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 enhancements 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 half of the jets were not accompanied with the plasma penetration. The conditions, required for the magnetosheath plasma penetration through the magnetopause, were investigated.