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 RE in the radial direction and up to 80 RE 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 XGSE or YGSE. 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.