Using Lunar Observations for Calibration Stability and Data Continuity for SNPP VIIRS and MODIS Reflected Solar Bands
Abstract
To meet objectives for assembling continuous Earth environmental data records from multiple satellite instruments, a key consideration is to assure consistent and stable sensor calibration across platforms and spanning mission lifetimes. Maintaining and verifying calibration stability in orbit is particularly challenging for reflected solar band (RSB) radiometer instruments, as options for stable references are limited. The Moon is used regularly as a calibration target, which has capabilities for long-term sensor performance monitoring and for use as a common reference for RSB sensor inter-calibration. Suomi NPP VIIRS has viewed the Moon nearly every month since launch, utilizing spacecraft roll maneuvers to acquire lunar observations within a small range of phase angles. The VIIRS Characterization Support Team (VCST) at NASA GSFC has processed the Moon images acquired by SNPP VIIRS into irradiance measurements for calibration purposes; however, the variations in the Moon's brightness still require normalizing the VIIRS lunar measurements using radiometric reference values generated by the USGS lunar calibration system, i.e. the ROLO model. Comparison of the lunar irradiance time series to the calibration f-factors derived from the VIIRS on-board solar diffuser system shows similar overall trends in sensor response, but also reveals residual geometric anomalies in the lunar model results. The excellent lunar radiometry achieved by SNPP VIIRS is actively being used to advance lunar model development at USGS. Both MODIS instruments also have viewed the Moon regularly since launch, providing a practical application of sensor inter-calibration using the Moon as a common reference. This paper discusses ongoing efforts aimed toward demonstrating and utilizing the full potential of lunar observations to support long-term calibration stability and consistency for SNPP VIIRS and MODIS, thus contributing to level-1B data quality assurance for continuity and monitoring global environmental changes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.A11N..01X
- Keywords:
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- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES;
- 0480 Remote sensing;
- BIOGEOSCIENCES;
- 1640 Remote sensing;
- GLOBAL CHANGE;
- 4894 Instruments;
- sensors;
- and techniques;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL