SMOS solar flux

The SMOS orbital solar flux dataset collects solar flux data at 1.4 GHz from 2010 to March 31st, 2025. Input data are the SMOS L1B full polarization mode v724 data available from the SMOS dissemination service portal (smos-diss.eo.esa.int, doi). Data are stored into txt files, each file covering one day. Daily files are sorted by year and month in dedicated folders. As the Sun signal is not always picked up by the main antenna-lobe of the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) payload, each file includes both main (front) lobe acquisitions, and acquisitions made by the back-lobe of the antenna. Data entries are arranged in chronological order, with all front-lobe data entered first, followed by all back-lobe data. Solar flux and Sun Brightness Temperature (BT) values are normalized to a constant Sun-Earth distance of 1 AU. To retrieve the not-normalized data, values need to be divided by the given Sun-Earth distance correction factor. Each acquisition is meant as the aggregation of roughly 50 min of data (SMOS half orbit for a given antenna plane), and is described by: Parameter Description / Format Acquisition Start Time Earliest timestamp used for each aggregate [UTC] Median Acquisition Time Median timestamp used for each aggregate [UTC] Acquisition Stop Time Latest timestamp used for each aggregate [UTC] Median solar flux Adjusted at a constant Sun-Earth distance of 1 AU [sfu] Median Sun BT Adjusted at a constant Sun-Earth distance of 1 AU [K] Standard deviation of the Sun BT Adjusted at a constant Sun-Earth distance of 1 AU [K] Number of snapshots Sample size Median Sun elevation angle Sun elevation angle in the antenna plane [rad] SMOS Orbit Number Orbit sequential ID number SMOS Orbit ANX Start Time Orbit ascending node start time [UTC] Note that data availability during 2010 is still limited as SMOS commissioning phase was still ongoing. Additionally, data coverage of the last days of August and the central days of April is limited due to low Sun elevation angles in the antenna plane. Future releases making use of subsequent L1OP processor versions will improve on the data coverage. For more information please contact: [e-mail], [e-mail], [e-mail] (C): Serco Italia S.p.A. 2025