EUV irradiance observations from SDO/Eve as a diagnostic of solar flares

Abstract

For the past six years, the EUV Variability Experiment (Eve) onboard the Solar Dynamics Observatory has been monitoring changes in the Sun's extreme ultraviolet output over a range of timescales. Its primary function is to provide measurements of the solar spectral irradiance that is responsible for driving fluctuations in Earth's ionosphere and thermosphere. However, despite its modest spectral resolution and lack of spatial information, the Eve spectral range contains many lines and continua that have become invaluable for diagnosing the response of the lower solar atmosphere itself to an injection of energy, particularly during a flare's impulsive phase. In addition, high temperature emission lines can also be used to track changes in temperature and density of flaring plasma in the corona. The high precision of Eve observations are therefore crucial in helping us understand particle acceleration and energy transport mechanisms during solar flares, as well as the origins of the Sun's most geoeffective emission.