Improvement in the characterization of MODIS subframe difference

Yonghong Li; Amit Angal; Na Chen; Xu Geng; Daniel Link; Zhipeng Wang; Aisheng Wu; Xiaoxiong J. Xiong

doi:10.1117/12.2238636

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19 September 2016 Improvement in the characterization of MODIS subframe difference

Yonghong Li, Amit Angal, Na Chen, Xu Geng, Daniel Link, Zhipeng Wang, Aisheng Wu, Xiaoxiong J. Xiong

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Proceedings Volume 9972, Earth Observing Systems XXI; 99720W (2016) https://doi.org/10.1117/12.2238636
Event: SPIE Optical Engineering + Applications, 2016, San Diego, California, United States

Abstract

MODIS is a key instrument of NASA’s Earth Observing System. It has successfully operated for 16+ years on the Terra satellite and 14+ years on the Aqua satellite, respectively. MODIS has 36 spectral bands at three different nadir spatial resolutions, 250m (bands 1-2), 500m (bands 3-7), and 1km (bands 8-36). MODIS subframe measurement is designed for bands 1-7 to match their spatial resolution in the scan direction to that of the track direction. Within each 1 km frame, the MODIS 250 m resolution bands sample four subframes and the 500 m resolution bands sample two subframes. The detector gains are calibrated at a subframe level. Due to calibration differences between subframes, noticeable subframe striping is observed in the Level 1B (L1B) products, which exhibit a predominant radiance-level dependence. This paper presents results of subframe differences from various onboard and earth-view data sources (e.g. solar diffuser, electronic calibration, spectro-radiometric calibration assembly, Earth view, etc.). A subframe bias correction algorithm is proposed to minimize the subframe striping in MODIS L1B image. The algorithm has been tested using sample L1B images and the vertical striping at lower radiance value is mitigated after applying the corrections. The subframe bias correction approach will be considered for implementation in future versions of the calibration algorithm.

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Yonghong Li, Amit Angal, Na Chen, Xu Geng, Daniel Link, Zhipeng Wang, Aisheng Wu, and Xiaoxiong J. Xiong "Improvement in the characterization of MODIS subframe difference", Proc. SPIE 9972, Earth Observing Systems XXI, 99720W (19 September 2016); https://doi.org/10.1117/12.2238636

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