Development of a EUMETSAT AC SAF merged Morning NO2 Climate Data Record and its application

Abstract

As part of the EUMETSAT Satellite Application Facility on Atmospheric Composition Monitoring (AC SAF) and the ESA Climate Change Initiative (CCI) Precursors project, a harmonized long-term climate data record (CDR) for nitrogen dioxide (NO2) has been developed using morning observations from GOME, SCIAMACHY, and GOME-2A, B and C. This work presents a newly merged NO2 CDR based on improved Level-2 products and provides user-friendly Level-3 datasets to support both scientific research and public interest. The dataset incorporates improved spectral fitting, updated a priori profiles from CAMS reanalysis, inter-sensor bias corrections, and detailed uncertainty estimates. Validation against long-term ground-based measurements confirms its consistency and reliability. This multi-decadal morning NO2 CDR, spanning from 1997 to the present, supports long-term trend analysis and studies of low-frequency climate variability, including climate normal and anomalies for EUMETSAT’s Climate Anomalies and Normals Service. Future observations from the Sentinel-5 mission will further extend this dataset, ensuring long-term continuity and improving our understanding of atmospheric composition changes.