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Proceedings Paper

On-orbit performance and calibration improvements for the reflective solar bands of Terra and Aqua MODIS
Author(s): Amit Angal; Xiaoxiong (Jack) Xiong; Aisheng Wu; Hongda Chen; Xu Geng; Daniel Link; Yonghong Li; Andrew Wald; Jake Brinkmann
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Paper Abstract

Moderate Resolution Imaging Spectroradiometer (MODIS) is the keystone instrument for NASA’s EOS Terra and Aqua missions, designed to extend and improve heritage sensor measurements and data records of the land, oceans and atmosphere. The reflective solar bands (RSB) of MODIS covering wavelengths from 0.41 μm to 2.2 μm, are calibrated on-orbit using a solar diffuser (SD), with its on-orbit bi-directional reflectance factor (BRF) changes tracked using a solar diffuser stability monitor (SDSM). MODIS is a scanning radiometer using a two-sided paddle-wheel mirror to collect earth view (EV) data over a range of ±55° off instrument nadir. In addition to the solar calibration provided by the SD and SDSM system, lunar observations at nearly constant phase angles are regularly scheduled to monitor the RSB calibration stability. For both Terra and Aqua MODIS, the SD and lunar observations are used together to track the on-orbit changes of RSB response versus scan angle (RVS) as the SD and SV port are viewed at different angles of incidence (AOI) on the scan mirror. The MODIS Level 1B (L1B) Collection 6 (C6) algorithm incorporated several enhancements over its predecessor Collection 5 (C5) algorithm. A notable improvement was the use of the earth-view (EV) response trends from pseudo-invariant desert targets to characterize the on-orbit RVS for select RSB (Terra bands 1-4, 8, 9 and Aqua bands 8, 9) and the time, AOI, and wavelength-dependent uncertainty. The MODIS Characterization Support Team (MCST) has been maintaining and enhancing the C6 algorithm since its first update in November, 2011 for Aqua MODIS, and February, 2012 for Terra MODIS. Several calibration improvements have been incorporated that include extending the EV-based RVS approach to other RSB, additional correction for SD degradation at SWIR wavelengths, and alternative approaches for on-orbit RVS characterization. In addition to the on-orbit performance of the MODIS RSB, this paper also discusses in detail the recent calibration improvements implemented in the MODIS L1B C6.

Paper Details

Date Published: 2 May 2016
PDF: 9 pages
Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 98811F (2 May 2016); doi: 10.1117/12.2223912
Show Author Affiliations
Amit Angal, Science Systems and Applications, Inc. (United States)
Xiaoxiong (Jack) Xiong, NASA Goddard Space Flight Ctr. (United States)
Aisheng Wu, Science Systems and Applications, Inc. (United States)
Hongda Chen, Science Systems and Applications, Inc. (United States)
Xu Geng, Science Systems and Applications, Inc. (United States)
Daniel Link, Science Systems and Applications, Inc. (United States)
Yonghong Li, Science Systems and Applications, Inc. (United States)
Andrew Wald, Global Science and Technology Inc. (United States)
Jake Brinkmann, Science Systems and Applications, Inc. (United States)


Published in SPIE Proceedings Vol. 9881:
Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV
Xiaoxiong J. Xiong; Saji Abraham Kuriakose; Toshiyoshi Kimura, Editor(s)

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