MODIS solar diffuser on-orbit degradation characterization using improved SDSM screen modeling

H. Chen; X. Xiong; A. Angal; Z. Wang; A. Wu

doi:10.1117/12.2239950

14 December 2016 MODIS solar diffuser on-orbit degradation characterization using improved SDSM screen modeling

H. Chen, X. Xiong, A. Angal, Z. Wang, A. Wu

Proceedings Volume 10000, Sensors, Systems, and Next-Generation Satellites XX; 100000X (2016) https://doi.org/10.1117/12.2239950
Event: SPIE Remote Sensing, 2016, Edinburgh, United Kingdom

Abstract

The Solar Diffuser (SD) is used for the MODIS reflective solar bands (RSB) calibration. An on-board Solar Diffuser Stability Monitor (SDSM) tracks the degradation of its on-orbit bi-directional reflectance factor (BRF). To best match the SDSM detector signals from its Sun view and SD view, a fixed attenuation screen is placed in its Sun view path, where the responses show ripples up to 10%, much larger than design expectation. Algorithms have been developed since the mission beginning to mitigate the impacts of these ripples. In recent years, a look-up-table (LUT) based approach has been implemented to account for these ripples. The LUT modeling of the elevation and azimuth angles is constructed from the detector 9 (D9) of SDSM observations in the MODIS early mission. The response of other detectors is normalized to D9 to reduce the ripples observed in the sun-view data. The accuracy of all detectors degradation estimation depends on how well the D9 approximated. After multiple years of operation (Terra: 16 years; Aqua: 14 years), degradation behavior of all detectors can be monitored by their own. This paper revisits the LUT modeling and proposes a dynamic scheme to build a LUT independently for each detector. Further refinement in the Sun view screen characterization will be highlighted to ensure the degradation estimation accuracy. Results of both Terra and Aqua SD on-orbit degradation are derived from the improved modeling and curve fitting strategy.

Conference Presentation

Citation Download Citation

H. Chen, X. Xiong, A. Angal, Z. Wang, and A. Wu "MODIS solar diffuser on-orbit degradation characterization using improved SDSM screen modeling", Proc. SPIE 10000, Sensors, Systems, and Next-Generation Satellites XX, 100000X (14 December 2016); https://doi.org/10.1117/12.2239950

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