Solar wind plasma correlations between IMP 8, INTERBALL‐1, and WIND

Abstract

Solar wind plasma flux correlations between data from three spacecraft (IMP 8, WIND, and INTERBALL‐1) were analyzed for approximately 4 months during late 1995 and mid 1996 (near solar minimum) in order to investigate the local homogeneity of the solar wind. The data were split into 6‐hour segments, resulting in a total of 397 segments where data from at least one pair of spacecraft could be correlated. The results show that the average flux correlation was 0.7 over distances ranging from 0 to 220 R E in the radial direction and up to 80 R E perpendicular to the Earth‐Sun line. 43% of the segments studied had correlation coefficients of at least 0.8, while only 19% of the segments had correlation coefficients less than 0.5. The additional lags, after performing radial advection shifts at the plasma bulk speed, cluster near zero (71% of the best correlations occur with lags under 10 min), implying that the advection shift is a good approximation of the propagation time for the structures being correlated. There appeared to be no dependence of the correlation on spacecraft separation in either X GSE or Y GSE . The best organizers of the flux correlation appear to be the value of the flux and the standard deviations of the flux and the density.