Speaker
Description
Programmed as an element of ESA’s Earth Watch programme, Atmospheric Limb Tracker for Investigation of the Upcoming Stratosphere (ALTIUS) has been developed as a gap filler mission responding to the urgent need to continue the global, long-term monitoring of stratospheric ozone, other trace gases and aerosols at the vertical resolution of the order of a few km. Scheduled for operation in the 2025-2029 period, ALTIUS will contribute near-real-time data to operational services like the Copernicus Atmosphere Monitoring Service (CAMS) and the Belgian Assimilation System of Chemical ObsErvations (BASCOE). ALTIUS will also provide consolidated data records to the Climate Data Store (CDS) of the Copernicus Climate Change Service (C3S) and to international assessments endorsed by the World Meteorological Organization (WMO) and the World Climate Research Programme (WCRP), as well as new research data needed for a better understanding of the upper atmosphere.
This contribution introduces the plan being developed for the geophysical validation of ALTIUS atmospheric composition data. After an overview of the user requirements against which ALTIUS data will have to be validated, the different objectives of ALTIUS validation during the commissioning phase of the mission and beyond will be discussed. The validation approach combines: (i) comparisons to independent ground-based measurements collected from monitoring networks contributing to WMO’s Global Atmosphere Watch (GAW), (ii) comparisons to other satellites like JPSS-2 OMPS and ACE extending the ground-based validation to the global domain, and (iii) quality assessments using modelling support. A dedicated validation service will perform baseline monitoring of ALTIUS data quality with an operational validation system, and in-depth validation producing consolidated results and support to the evolution of the retrieval algorithms. An Announcement of Opportunity for the calibration and validation (Cal/Val) of ALTIUS will be published approximately two years before launch, with the aim to open the ALTIUS Cal/Val to the international community and to a wider range of external data and activities, to foster exchanges within the validation community and with the instrument and algorithm experts, and to promote the use of ALTIUS data.
