Radiometric Measurement Comparison on the Integrating Sphere Source Used to Calibrate the Moderate Resolution Imaging...

Area of Science:

• Earth Science
• Radiometry
• Instrument Calibration

Background:

• Accurate radiometric calibration is crucial for Earth Observing System (EOS) instruments.
• Integrating sphere sources are key components for calibrating these instruments.

Purpose of the Study:

• To validate the radiometric scales of integrating sphere sources used for EOS instrument calibration.
• To support the calibration of Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) instruments.

Main Methods:

• A radiometric measurement comparison was conducted in May 1998 at Raytheon/Santa Barbara Remote Sensing (SBRS).
• Stable transfer radiometers from NIST, NASA's GSFC, and the University of Arizona were used.
• Measurements were compared against the Spherical Integrating Source (SIS100) calibration by SBRS.

Main Results:

• Measured radiances from transfer radiometers agreed within ±3% with SBRS calibration in the visible to near-infrared spectrum.
• Agreement was within combined uncertainties for wavelengths up to 2200 nm.
• Transfer radiometers showed higher values in the near-infrared and lower values in the blue compared to SBRS calibration.

Conclusions:

• The radiometric scale of the SIS100 by SBRS was validated by independent measurements.
• Results supplement previous comparisons for other EOS instruments like MISR and ASTER.
• The study confirms the reliability of the radiometric scales for critical Earth observation missions.