C3S2_620 Improved treatment of the stratosphere in C3S reanalyses

Description

ECMWF, as the Entrusted Entity for the Copernicus Climate Change Service (C3S), invites Tenders for development activities to assess and improve the treatment of the stratosphere in climate reanalyses. This will be achieved by completing developments in the ECMWF Integrated Forecasting System (IFS) and performing assimilation experiments with observations of upper atmospheric temperature and humidity. This work will assess the quality of ERA6 temperature and humidity in the upper atmosphere shortly after production and evaluate a method for correcting model biases in the stratosphere in early periods of future reanalyses using information from the data-rich modern era. To support the validation of these developments, high-quality in-situ observation data records shall be acquired. ECMWF intends to award a single Framework Agreement for a period of maximum 30 months, which shall be implemented via a single Service Contract expected to commence in Q2 2026.