Long-term Evolution of the Solar Corona Using PROBA2 Data

We use the SWAP imager onboard PROBA2 mission to study the evolution of large-scale EUV structures in the solar corona observed throughout Solar Cycle 24 (from 2010 to 2019). We look at the evolution of the coronal features on-disk and at different heights above the solar surface and compare them at different phases of the solar cycle, as well as with sunspot number evolution and with the PROBA2/LYRA signal. We find that the three time series (SWAP on-disk average brightness, sunspot number and LYRA irradiance) are very well correlated, with correlation coefficients around 0.9. Large-scale off-limb structures were visible from around March 2010 to around March 2016, meaning that they were absent at the minimum phase of solar activity.