Dissimilarity in the Evolution of Solar EUV and Solar Radio Emission (2800 MHz) During 1999-2002

Author: R. P. Kane
Instituto Nacional de Pesquisas Espacias, Brazil

For solar UV and EUV, the F10 (2800 MHZ solar radio emission), Lyman alpha and Mg II are used as proxies. During 1999-2002, many solar indices showed two maxima, one near July 2000 and another near January 2002. For F10 and Lyman alpha, the second maximum was higher than the first maximum by ~10%, but for Rz, the second maximum was lower than the first maximum by ~4%. The observed EUV (26-34 nm from SEM-SOHO) had the second maximum higher than the first maximum, but only by ~3.5%. The model values given in SOLAR2000 (Tobiska et al. [2000] website) show patterns of 26-34 nm qualitatively similar to F10, with second maximum larger than the first maximum, but the magnitude is much larger, ~20%. Thus, there is a discrepancy of ~15% between observed EUV and SOLAR2000 model EUV during 2001-2002. The model values are overestimates and do not seem to have taken into account the observed EUV values.