HR: 1340h
AN: SM23B-0412    [Abstracts]
TI: Multi-Scale Multi-Point Analysis of Interplanetary Discontinuities in Different Solar Wind Conditions
AU: * Knetter, T
EM: knetter@geo.uni-koeln.de
AF: University of Cologne, Albertus-Magnus-Platz, Cologne, 50923 Germany
AU: Neubauer, F M
EM: neubauer@geo.uni-koeln.de
AF: University of Cologne, Albertus-Magnus-Platz, Cologne, 50923 Germany
AU: Horbury, T
SM23B-0412 AF: Imperial College, Prince Consort Road, London, SW72BW United Kingdom
AU: Lucek, E
SM23B-0412 AF: Imperial College, Prince Consort Road, London, SW72BW United Kingdom
AU: Dandouras, I
SM23B-0412 AF: CESR/CNRS, 9, avenue du Colonel Roche, Toulouse, 4346 31028 France
AU: Reme, H
SM23B-0412 AF: CESR/CNRS, 9, avenue du Colonel Roche, Toulouse, 4346 31028 France
AB: Recent multi-spacecraft observations have indicated that the Minimum Variance Analysis (MVA), an established and widely used single-spacecraft technique to compute normals of discontinuities, is much less reliable than previously assumed. Making use of the time differences between the occurrence of the discontinuity at each of the four Cluster spacecraft it was shown that the number of rotational discontinuities (RDs) in the solar wind has been dramatically overestimated in the last three decades. However, these recent conclusions are solely based on relatively small spacecraft separations (900 km) and only slow solar wind data was available at the time of the first analysis. Remaining open questions are: Do these results also hold for larger spacecraft separations, i.e., for enhanced accuracy in normal determination? How accurate is the timing method? What is the situation in fast solar wind emanating from coronal holes on the Sun, where particularly many RDs were found according to single-spacecraft studies? Using a range of Cluster separations (from 100 km to 5000 km) in both slow solar wind and fast coronal hole flow plus a detailed error analysis we show that with increasing triangulation accuracy the component of the magnetic field threading the discontinuity surface even decreases. The error analysis demonstrates that all 366 solar wind events in our data set are consistent with tangential discontinuities (B_n=0). This is particularly true for the coronal hole flow. These new results are in apparent disagreement to all previous studies. As a consequence, proposed generation mechanisms for solar wind discontinuities and their implication for coronal heating must be revisited.
UR: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=36142
DE: 2109 Discontinuities (7811)
DE: 2134 Interplanetary magnetic fields
DE: 7811 Discontinuities (2109)
DE: 7827 Kinetic and MHD theory
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005