The Future European CO2 Monitoring Mission and the Need of a Multi-Angle Polarimeter to Characterize the Atmospheric Light Path

Abstract:

The European Commission, and the European Space Agency (ESA) together with the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) are implementing the future Copernicus mission CO2M to monitor anthropogenic CO₂ emissions from space at country, regional and local scales. The constellation of three satellites is slated with a first launch in 2025, in time to provide input the UN’s second global stocktake of greenhouse gas emissions due three years later. With the objective to quantify anthropogenic CO₂ emissions, the CO2M mission will deliver CO₂ vertical columns with unprecedented high accuracy (<0.5 ppm) and precision (<0.7 ppm) and an effective weekly global coverage at mid-latitudes. The mission payload comprises three co-aligned instruments: (1) spectrometer units covering the near and shortwave infrared spectral bands around 0.45, 0.76, 1.6 and 2.0 m with moderate spectral resolution, (2) a multi-angle polarimeter observing radiances and the degree of linear polarization in up to 40 viewing directions in the ultraviolet, visible and near infrared, and (3) a cloud imager with a dedicated channel at 0.67 m for cumulus clouds and at 1.38 m for cirrus detection. This unique instrument suite will reduce scattering induced errors to a minimum, yielding better data coverage in particular for areas with strong (aerosol) air pollution, like India and China compared to current CO₂ sensors in space. Additionally, the CO2M payload will allow to deliver an aerosol data product with a unique combination of data coverage and data quality. It will significantly advance the accuracy of retrievals of optical and microphysical aerosol properties compared to past and present satellite instruments, as required for better quantification of the effect of aerosols on climate. In this presentation, we will demonstrate the mission objetives including the gain in data quality and yield by a synergistic use of the different observations. With the unique combination of the proposed state-of-the-art sensing concept, CO2M will be of great benefit for science, as well as for policy makers to achieve the challenging objectives of future CO₂ monitoring and related emission reduction efforts.