On the existence of characteristic microscale magnetohydrodynamic fluctuations inside a corotating interaction region at 2.5AU.
Abstract
A detailed analysis of small period (15900s) Magnetohydrodynamic (MHD) turbulence of the interplanetary magnetic field (IMF) has been made using Pioneer11 high resolution in time data (0.75s) inside a Corotating Interaction Region (C.I.R.) at a heliocentric distance of 2.5AU in 1973 (days 284286). The methods used here are hodogram analysis, minimum variance matrix analysis and coherence analysis. Inspection of the hodogram analysis gives evidence for finite amplitude nontransverse Alfven waves if 2min up to 8min averages of the IMF data are used. On the other hand this wave structure disappears if smaller or longer averages of the IMF data are taken under consideration. Minimum variance analysis gives evidence of linear polarized wave modes and coherence analysis shows that the field fluctuations are dominated by the magnetosonic fast modes with periods 15s to 900s. However it is also shown that some small amplitude Alfven waves are present in the trailing edge of this region with characteristic periods of 15 until to 200s. The results are discussed in terms of several theoretical mechanisms.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 November 1996
 Bibcode:
 1996A&A...315..319M
 Keywords:

 MHD;
 TURBULENCE;
 INTERPLANETARY MEDIUM;
 SOLAR WIND