We propose a simple model that computes the spectral profile of the solar irradiance in the hydrogen Lyman alpha line, H Ly‐ α (121.567 nm), from 1947 to present. Such a model is relevant for the study of many astronomical environments, from planetary atmospheres to interplanetary medium. This empirical model is based on the SOlar Heliospheric Observatory/Solar Ultraviolet Measurement of Emitted Radiation observations of the Ly‐ α irradiance over solar cycle 23 and the Ly‐ α disk‐integrated irradiance composite. The model reproduces the temporal variability of the spectral profile and matches the independent SOlar Radiation and Climate Experiment/SOLar‐STellar Irradiance Comparison Experiment spectral observations from 2003 to 2007 with an accuracy better than 10%.
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Kretzschmar et al. (2018) studied this question.