Developments on the instrument performance predictions and contamination modelling: the practical approach of ESA’s Sentinel-4 mission

ESA Sentinel-4 mission will monitor trace gas concentrations and aerosols in the Earth’s atmosphere with a 1-hour revisit frequency and unprecedented spatial resolution. Initial performance predictions, relying on literature/historical values for optical absorption coefficients, revealed considerable losses at the end of the mission lifetime caused mainly by high levels of absorption of light due to molecular contamination spread over the 39 optical surfaces of the UVIS channel. This publication describes the significant effort undertaken by Sentinel-4 team to establish more reliable and accurate performance predictions, and the importance of performing measurements under representative conditions of the instrument’s contamination environment. The refined performance prediction analysis was the final step of the activity, demonstrating that the end of life performance requirements of Sentinel-4 will be met.