Solar irradiance observations with PREMOS filter radiometers on the PICARD mission: In-flight performance and data release

Abstract

The PREcision Monitoring Sensor (PREMOS) is a solar radiometer on board the French PICARD mission that was launched in June 2010 and decommissioned in April 2014. Aims. The PREMOS radiometer obtains solar irradiance measurements in specific spectral windows in the UV, visible, and near- infrared. In this paper, the PREMOS data and calibration methods are presented. Methods. Using back-up channels, the degradation can theoretically be assessed to correct operational channels. However, a strong degradation within all PREMOS channels requires the application of additional methods, namely using back-up channels and assess- ing the degradation via a proxy-based model. Results. The corrected Level 3 PREMOS data are then used in different contexts in order to be validated. First, the signature of the p-mode are retrieved from the PREMOS data. The Venus transit allows us to empirically determine the intrinsic noise level within the PREMOS high cadence data for the visible and near-infrared channels. We then compare the PREMOS data directly to other data sets, namely from the SOLar-STellar Irradiance Comparison Experiment (SOLSTICE) and the Solar Irradiance Monitor (SIM) instru- ments on board the SOlar Radiation and Climate Experiment (SORCE) spacecraft. Regarding the UV channels, we found an excellent correlation over the lifetime of the PREMOS mission. The ratio between SORCE and PREMOS observations is always less than 1%. Regarding the SSI measurements in the visible and near-infrared, a comparison of short-term variations (i.e. 27-day modulation) shows a rather good correlation by taking into consideration the intrinsic noise within both SIM and PREMOS observations.