Solar Spectral Irradiance (SSI) from CODET model to Study Planetary Exospheres: Earth and Mars

Jenny M Rodríguez-Gómez^*

• The Catholic University of America, Washington, United States

Solar variability and Solar Spectral Irradiance (SSI) are important to studying planetary atmospheres, particularly the Ionosphere-Thermosphere-Mesosphere (ITM) system, as well as planetary exospheres. This paper introduces new SSI time series from the CODET model, obtained at different geocentric distances, e.g., 3.0 R e , 6.6 R e and 8.0 R e (CODET R e model), at wavelengths of 21.1 nm and 19.3 nm. Additionally, modeled time series at Mars distance (CODET Mars model) are provided for 28.4 nm and 21.1 nm. A comparison with measurements from MAVEN/EUVM indicates that modeled SSI obtained from the CODET Mars model can be obtained with uncertainties ≤ 43% from October 19, 2014, to April 20, 2024. Thus, SSI from the CODET R e and CODET Mars models provides a fantastic opportunity to study exospheric/atmospheric dynamics and compare them with future observations. The impact of Solar Spectral Irradiance (SSI) on the Earth's upper atmosphere was analyzed using time series from the CODET model. Specifically, the study focused on the effect of SSI in EUV wavelengths and its influence on the Earth's atmosphere through geomagnetic storms, as measured by the Dst and Ap indices. This analysis shows that strong and moderate geomagnetic storms are associated with enhancements of SSI in EUV. These results highlight the importance of SSI in the study of planetary atmospheres. Thus, the CODET model plays an important role because the SSI modeled time series fills observational gaps, providing a reliable and long time series that covers the last solar cycles.