The new CAMS radiation service v4.6 - Methods Improvements and service evolution with a special focus on solar energy

International audience The Copernicus Atmosphere Monitoring Service (CAMS) operated by the European Center for Medium Range Forecast (ECMWF) provides open-data access to surface solar irradiance (SSI) through its CAMS Radiation Service (CRS). In CRS, observations from geostationary meteorological satellites are combined with modeled data for aerosols, water vapor, and ozone from the ECMWF CAMS Integrated Forecasting System (IFS) to derive irradiance at the Earth's surface. CRS data is provided for the Meteosat Second Generation (MSG) satellite field of view (Europe and Africa) from 2004 to the day before yesterday. Since its latest update v4.6, CRS also provides data for the HIMAWARI 8/9 satellite field of view (Asia and Australia) from 2016 to the day before yesterday. Time series in 1 min, 15 min, hourly and daily temporal resolution are produced 'on-the-fly' on user request at the desired location. In the expert mode, all input parameters e.g. aerosols, water vapour, clouds, surface albedo can also be accessed as additional time series. In addition to the standard access as single time series at the user’s individual target location, a gridded dataset for land surfaces of Europe and Africa for the years 2004-2022 is available. This is based on a retrieved collection of many time series in a 0.1° spatial grid and in 15 min temporal resolution which are re-structured to a gridded monthly data file. Besides the data access via the CAMS web page and API, the CAMS Radiation Service time series data is also operationally accessible via the python package pvlib since v0.9.0 (released on the 1st September 2021). The CRS v4.6 was released in October 2023. It includes a new version (v3.6) of the cloud-free module McClear which considers a new species of aerosol introduced in the CAMS IFS numerical weather model CY48r1. This new composition of aerosols is not retroactive and thus concerns only time-series which timestamps are July 2023 onwards. This new version has an update in the all sky model and has been extended to the HIMAWARI geostationary satellite field of view. CRS uses APOLLO Next Generation (APOLLO_NG) for deriving cloud information from weather satellites in the Heliosat-4 method (Qu et al., 2017; Schroedter-Homscheidt et al., 2022). APOLLO_NG is based on a probabilistic cloud detection (Klüser et al., 2015) and its usage in Heliosat-4 follows a detection approach that is highly optimized for solar energy needs. The method is operationally applied for Europe, Africa, the Middle East, Asia and Australia and has also been tested on the GOES-16 ABI instruments in North and South America. In addition, work is underway to deploy on APOLLO_NG the upcoming Meteosat Third Generation (MTG), which will even provide higher spatial and temporal resolutions.