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

Area of Science:

• Space physics
• Climate science
• Solar physics

Background:

• The Solar Radiation and Climate Experiment/Spectral Irradiance Monitor (SORCE/SIM) mission provided crucial solar spectral irradiance (SSI) data from 2003 to 2020.
• Understanding SSI variability is essential for climate modeling and space weather prediction.
• Instrument degradation due to the space environment can impact the accuracy of long-term SSI measurements.

Purpose of the Study:

• To present the methodology for correcting instrument-only degradation effects in SORCE/SIM SSI data.
• To ensure the accurate determination of solar spectral irradiance (SSI) variability across different solar cycles.
• To provide a reliable dataset for climate and solar physics research.

Main Methods:

• Utilized two functionally identical prism spectrometers with independent detectors for cross-calibration.
• Developed an instrument-only degradation correction methodology.
• The correction method makes no assumptions about the SSI variability's magnitude, slope, or wavelength dependence.

Main Results:

• The SORCE/SIM instrument successfully measured SSI during the descending phase of Solar Cycle 23, Solar Cycle 24 maximum, and the SC24/SC25 minimum.
• The applied degradation correction method is strictly instrumental and robust.
• The resulting SSI dataset is reliable for studying solar variability and its climate impacts.

Conclusions:

• The SORCE/SIM mission successfully provided a long-term record of SSI.
• The instrument-only degradation correction ensures the accuracy and reliability of the SSI data.
• This validated dataset is valuable for advancing our understanding of solar influences on Earth's climate.