Abstract

Long-Term Trend Analysis for the Spectral Irradiance Monitor (SIM) and the Solar Radiation and Climate Experiment (SORCE)

Author(s): Anne Ellis

The Solar Radiation and Climate Experiment (SORCE) mission of NASA is equipped with four instruments, one of which is the X-ray Photometer System (XPS). Key measurements of Total Solar Irradiance (TSI) and Solar Spectrum Irradiance were made by the SORCE spacecraft between 2003 and 2020. (SSI). The XPS is a collection of photometers used to gauge the sun's X-Ray Ultraviolet (XUV) irradiance at wavelengths less than 34 nm and the strong hydrogen emission at 121.6 nm. The accuracy of the XPS measurements is roughly 20%, and each photometer has a spectral bandpass of about 7 nm. Updates to the final data-processing algorithms are presented for the XPS solar-irradiance data products. Improvements to the instrumental adjustments for background signal, visible-light signal, and deterioration trends are included in these processing revisions. The Solar Radiation and Climate Experiment/Spectral Irradiance Monitor (SORCE/SIM) instrument was launched on January 25, 2003, and its mission will end on February 25, 2020. The SORCE/SIM offers a singular data set of the variability in Solar Spectral Irradiance (SSI) throughout the descending portion of Solar Cycle 23 (SC23) from April 2003 to February 2009, the weaker solar-maximum circumstances of SC24, and the quiet SC24/SC25 low. The unmistakable identification of the impacts of the space environment and solar-exposure-related degradation mechanisms is necessary for the assessment of the size and phase of SSI fluctuations. The instrument-only SIM adjustments are based on a comparison of two functionally identical (mirror image) prism spectrometers with four independent detectors in each spectrometer channel.