Evidence of different magnetotail responses to small solar wind pressure pulses depending on IMF Bz polarity

Abstract

The response of the magnetotail to small flux rope associated pressure pulses depends on the IMF Bz polarity. Clear and large amplitude magnetotail reverse polarity South-then-North traveling compression regions (SN TCRs) are observed when the pressure pulse is associated with the northward IMF interval of the flux rope. These tail signatures correspond to small-scale (<10 minute duration) pulses of the solar wind dynamic pressure located in front of and within the small-scale flux ropes. Pressure pulses associated with IMF Bz southward are either absent or give rise to smaller amplitude compressions and less systematic lobe Bz rotations. These results suggest that the orientation of the IMF Bz plays a critical role in modulating the magnetotail response to solar wind dynamic pressure pulses.