On the correlation between daily GCR intensity values and LDE-type flare index (1987, 1988, 1990 and 1992)

Abstract The correlation analysis between daily values of Calgary Galactic Cosmic Ray intensity (CNI) and LDE-type flare index (FI) reveals the following results: in all years under consideration, the CNI-FI anticorrelation is small, but statistically significant. The yearly CNI-FI trend depends on yearly heliospherical conditions and on their 22-year cyclical changes. At the onset of the 22-nd cycle (in 1987) the CNI-FI relation had broad minimum, similar to the result for non-flare SXR background corona in 1987. In 1988 and 1992 the typical short-term CNI-FI lag (from − 1 to − 3 days) was found, indicating the presence of local heliospherical CNI modulation sources. In 1990, the CNI-FI correlation has two comparable, large minima at − 22 as well as − 9 day CNI lags. Such double peak form of the 1990's CNI-FI minimum is consistent with the existence of two, amplitudinally balanced CNI modulation sources in the 1990's heliosphere. The first source seems to be a substantial Global Merged Interaction Region (GMIR) located in the outer heliosphere (producing the − 22 day CNI lag). The second source was a typical local heliospherical structure, indicated by short-term CNI lags.