CHIRPS Precipitation, Copernicus DEM, (Ag)ERA5 Meteorological Data, GEOS-5 Meteorological Data, IMERG Precipitation, Landsat satellites, MODIS sensors, MSG satellites, Sentinel-2 satellites, VIIRS sensors and WorldCover Land Cover

MSG

Atmospheric transmissivity determines the fraction of solar radiation that transverses through the atmosphere and reaches the Earth’s surface. Cloud cover information is used to quantify the transmissivity of the atmosphere for shortwave solar radiation. The Meteosat Second Generation (MSG) geostationary satellite measures cloud cover with time steps of 15 minutes. Derived down-welling surface fluxes provided are reliable inputs for calculating daily transmissivity. MSG is available for Africa/Europe and for the Indian Ocean (MSG-IODC) at approximately 3km.

Purpose of data

The MSG shortwave radiation product is used to calculate daily transmissivity which, in turn, is used to produce the Solar radiation data component for all levels.

Approach

There are three sources of data: 1. CMSAF: EUMETSAT's Climate Monitoring Satellite Application Facility (CM-SAF) provides historical and NRT daily Downward Surface Shortwave flux data for Europe/Africa, excluding part of the current L2 area of interest (e.g. Iran), since 2018. There is also a historical product (CMSAF clima) that covers a longer time period. Data can only be downloaded manually. 2. LSA SAF: The LSA SAF Data Service produces historically and NRT available daily MSG Downward Surface Shortwave Flux (MDSSF) . This service provides MSG and MSG-IODC data, in which the first product covers mainly Africa and Europe, and the second one provides a good coverage of the Indian Ocean, the Middle Eastern countries, and most of the Asian continent. Moreover, the LSA SAF raw products have already a water mask applied, resulting in missing data for smaller islands. 3. KNMI: The Royal Netherlands Meteorological Institute (KNMI) produces several products within the Cloud Physical Properties (CPP) algorithm based on the MSG Spinning Enhanced Visible and InfraRed Imager (SEVIRI) sensor. One of these products is a shortwave radiation product in the form of 15-minute surface downwelling solar radiation (sds”), in total 48 files per day. This product has a resolution of 4 km and is only available NRT. Also, it does not include the Indian Ocean (MSG-IODC) dataset.

For L2 and L3 data, the 3 services' (LSA SAF, CMSAF, and KNMI) products are combined to get full spatial and temporal coverage, depending on data availability.

Challenges

The coarse resolution of the data will have an effect on the estimation of solar radiation at higher levels. At the moment no higher resolution data is available for the project area. Combination of data products is required to get full coverage of the current L2 area.

Alternative sources

The GEOS-5 data assimilation system may deliver the same information but at a coarse resolution. In the case of historical processing, and the final run of the analysis, the AgERA5 Solar radiation flux product could be used as the alternative source. This dataset is produced on behalf of the Copernicus Climate Change Service, is based on the hourly ECMWF ERA5 data at surface level, and has a finer horizontal resolution of 0.1° x 0.1°. Due to the 8 days latency of the product, it will be used only the final run and historical processing. For L1 the GEOS-5 dataset will be used to ensure global consistency.

Meteosat Third Generation (MTG) was launched on 13 December 2022 and will scan Europe and Africa . MTG will deliver more frequent data (full disc every 10 minutes versus 15 minutes currently from MSG), improved spatial resolution (1km/3km for MSG) and a better radiometric and spectral resolution (16 channels versus 12 channels for MSG).