FDR4ATMOS: Adding GOME-2 data to the GOME-1/SCIAMACHY harmonised FDR product

Kurzfassung

The Fundamental Data Record for ATMOSpheric Composition (FDR4ATMOS) project is part of the European Space Agency (ESA) Long Term Data Preservation (LTDP) programme. A Fundamental Data Record (FDR) is a long-term record of selected Earth observation Level 1 parameters (radiance, irradiance, reflectance), possibly multi-instrument, which provides improvements of performance beyond the individual mission data sets. The project served as a pathfinder for harmonisation of spectrally highly resolved data from various instruments. The initial phase of the project delivered a first version of the FDR with harmonised Earth reflectances and solar irradiances from GOME-1 and SCIAMACHY. This combined data set spans a 17 year period offering spectrally highly resolved data essential for air quality applications, climate research, ozone trend analysis, and UV radiation studies. The FDR provides the first-ever harmonised data set for high-resolution spectrometers. Since the retrieval of atmospheric trace gas content and other parameters depends on the relative structures of the spectrum, any harmonisation effort must preserve these spectral structures while also addressing broader band differences between the instruments. The FDR4ATMOS project was extended at the end of 2023 to also include Level 1b data from the GOME-2 instrument series with the aim to provide an updated time series covering data from GOME-1, SCIAMACHY and GOME-2 (1995 - 2024). Additionally, the project will develop a lunar data set from data of SCIAMACHY and GOME-2. Building on the experience of the harmonisation of GOME-1 and SCIAMACHY, we will further refine our harmonisation method. In this paper we will give an overview of the current status of the FDR4ATMOS project, presenting detailed insights into the lunar data set development, the solar irradiance harmonization, and upcoming plans for the harmonisation of Earth reflectances.