Interplanetary small‐ and intermediate‐sized magnetic flux ropes during 1995–2005

Abstract

We present a comprehensive survey of 125 small‐ and intermediate‐sized interplanetary magnetic flux ropes during solar cycle 23 (1995–2005) using Wind in situ observations near 1 AU. As a result, we found the following: (1) The annual number of small‐ and intermediate‐sized interplanetary magnetic flux ropes is not very sensitive to the solar cycle, but its trend is very similar to that of magnetic clouds (MCs). (2) Average speeds of the individual small‐ and intermediate‐sized interplanetary magnetic flux ropes varied from 289 to 790 km/s with a mean value of 420 ± 86 km/s. Most small‐ and intermediate‐sized interplanetary magnetic flux ropes were found to have a propagation speed similar to typical slow speed solar wind speed, and only a few small‐ and intermediate‐sized interplanetary magnetic flux ropes had speeds comparable to the typically high speed solar wind. (3) Average magnetic field strength for small‐ and intermediate‐sized interplanetary magnetic flux ropes is less than the average magnetic field strengths of MCs, while it is larger than that of background solar wind. (4) The distributions of the axial orientations for small‐ and intermediate‐sized interplanetary magnetic flux ropes are also similar to that of MCs. The results show that small‐ and intermediate‐sized interplanetary magnetic flux ropes and MCs have many similar (or relative) characters. So we suggest that both MCs and small‐ and intermediate‐sized interplanetary magnetic flux ropes originate from solar eruptions.