Towards operational monitoring and assimilation of visible reflectances at ECMWF

Satellite observations are critical for numerical weather prediction (NWP), yet the full potential of visible and near-infrared spectral data remains to be exploited. In recent years, ECMWF has been advancing efforts to incorporate visible satellite observations into the analysis and forecasting of clouds and aerosols within the Integrated Forecasting System (IFS). These developments are now reaching operational maturity. We present visible reflectance monitoring and assimilation experiments using observations from various satellite instruments: Spinning Enhanced Visible and Infrared Imager (SEVIRI), Flexible Combined Imager (FCI), Advanced Himawari Imager (AHI), Advanced Baseline Imager (ABI), and Ocean and Land Colour Instrument (OLCI). Our study assesses the first-ever successful experimental assimilation of visible (655 nm) all-sky satellite observations in the IFS. A comprehensive evaluation of these experiments demonstrates that visible reflectance assimilation can improve the model analysis of clouds by better fitting the model trajectory to observations in visible reflectance space. We will also discuss the remaining challenges related to the future operational assimilation of visible observations, including error modelling and biases. Our findings underscore the vast potential of visible spectral observations for operational numerical weather prediction and future re-analysis products.