A novel satellite optical sensing system for atmospheric NO2: motivation, concept design, and instrument modelling

Health officials, policymakers and the public are increasingly aware of the dangers of long-term exposure to air pollution. Nitrogen dioxide (NO₂) is an air pollutant that is directly linked with human respiratory diseases and indirectly linked via the role of NO₂ in the production of surface ozone and particulate matter. Current NO₂ monitoring networks depend largely on stationary systems sampling air locally, but these lack adequate spatial coverage to fully characterise how pollution varies throughout a city on a street-by-street level. Because NO₂ is typically co-emitted with CO₂ during high-temperature combustion, detecting NO₂ plumes can also be used effectively to improve estimates of CO₂ emissions from human activities. There is therefore an urgent need to develop NO₂ monitoring systems that will deliver data with high spatial and temporal coverage to improve actionable information about air pollution and carbon emissions. Here, we introduce SNEEZI (Sensing NO₂ Emissions to Evaluate net-Zero Initiatives) – a project to develop a lightweight NO₂ spectral imaging instrument designed for deployment on a constellation of small satellites to allow for NO₂ monitoring with high spatial and temporal resolution. We present the initial optical design for the system, as well as modelled instrument performance.