EUV97: Improvements to EUV Irradiance Modeling in the Soft X-Rays and FUV

Abstract

EUV97 is a solar EUV empirical model that incorporates revised soft X-ray fluxes from the SOLRAD-11 satellite (1976-1979) and uses Lα recently recalibrated to the UARS satellite (1991-present) SOLSTICE Lα. The soft X-ray data have been revised from the original flux values using Mewe's spectral fits to the data. The recalibrated AE-E and SME Lα datasets use UARS Lα for absolute flux values to provide two solar cycles of Lα irradiance extending back to 1977. Lα is used by EUV97 as a proxy for chromospheric EUV irradiances. The EUV97 empirical solar model takes its heritage from the EUV91 model based on a multiple linear regression technique that fits soft X-ray and EUV irradiances to 10.7 cm flux for transition region and coronal emissions or to Lα and Hei 10830 Ú EW for chromospheric emissions.