Characterization of the on-orbit response versus scan angle for Terra MODIS SWIR bands in Collection 7

Mu, Qiaozhen; Xiong, Xiaoxiong; Twedt, Kevin A.; Angal, Amit; Geng, Xu

doi:10.1117/1.jrs.16.024520

Cited by 4 publications

(2 citation statements)

References 23 publications

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“…The trends of DCC signals over time are used to apply adjustments to the Terra MODIS SWIR bands calibration so that the DCC reflectance trends in C7 will be stable over the entire mission. 16 For Aqua MODIS, the DCC are processed in the same way and are used to evaluate the performance of both C6.1 and C7 calibration for the RSB, but are not used directly in the calibration.…”

Section: DCCmentioning

confidence: 99%

Impact of satellite orbit drift on MODIS Earth scene observations used in calibration of the reflective solar bands

Twedt,

Xiong,

Geng

et al. 2023

Earth Observing Systems XXVIII

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After more than 20 years in orbit, NASA's Terra and Aqua satellites have both started drifting away from their historically maintained orbits. The MODIS instruments on Terra and Aqua continue to collect valuable Earth observation data, but the changing orbits present a challenge for maintaining accurate calibration. The MODIS reflective solar bands (RSB), spanning the wavelength range from 412 nm to 2130 nm, are calibrated on orbit using a combination of regular data collections from an on-board solar diffuser, the Moon, and pseudo-invariant Earth scenes. Starting in the Collection 6 Level 1B (L1B) data products, the RSB calibration began using data from desert targets for a few of the visible bands to better track changes in the response versus scan angle that could not be captured by the on-board calibration. The use of Earth scene data has been extended recently for Terra MODIS calibration in Collection 6.1 (C6.1) and the upcoming Collection 7 (C7) L1B to also include data from ocean scenes and deep convective clouds (DCC). Drifts in both the orbit inclination and ground track of Terra and Aqua lead to changes in the solar illumination angles and satellite view angles of the Earth scenes. We discuss how these orbital changes impact the desert and DCC targets used for MODIS RSB calibration and present the accompanying changes made to our C6.1 and C7 calibration algorithms. We also discuss remaining future challenges, such as better characterization of bi-directional reflectance distribution functions, and possible alternative calibration strategies.

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Section: DCCmentioning

confidence: 99%

Impact of satellite orbit drift on MODIS Earth scene observations used in calibration of the reflective solar bands

Twedt,

Xiong,

Geng

et al. 2023

Earth Observing Systems XXVIII

Self Cite

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“…Secondly, the SWIR bands rely on RVS determined from prelaunch in C6/6.1. In C7, a time-dependent change in RVS is applied using observations from the DCC to correct for the long-term drifts [22,27]. The DCC data are used to generate an on-orbit RVS for bands 5 and 26 and to correct inaccuracies of the SD calibration for all four SWIR bands 5-7 and 26.…”

Section: C7 Calibration Improvement Over C6mentioning

confidence: 99%

Assessment of the Radiometric Calibration Consistency of Reflective Solar Bands between Terra and Aqua MODIS in Upcoming Collection-7 L1B

Wu,

Xiong,

Angal

et al. 2023

Remote Sensing

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Two MODIS sensors onboard the Terra and Aqua spacecraft have been successfully operating for over twenty-three and twenty-one years, respectively, providing the worldwide user community with high-quality imagery and radiometric Earth observations of the land, atmosphere, cryosphere, and oceans. This study provides an assessment of the radiometric calibration stability and consistency of Terra and Aqua MODIS RSB using the L1B from the upcoming Collection 7 release. Several independent vicarious approaches based on measurements from the Libya-4 desert, Dome C, DCC, and SNO are used to assess the calibration stability at the beginning of scan, nadir, and end of scan. Results indicate that both Terra and Aqua RSB are stable to within 1% over their mission periods. Comparison of the normalized reflectances with either a BRDF model or a common reference sensor provides a radiometric assessment of Terra and Aqua calibration consistency. Comparison results show the VIS/NIR bands are in good agreement around the nadir and at the beginning of the scan for all the approaches. For cases at the end of the scan, the agreement varies depending on the approach but is typically within ±2%. The differences observed in the SWIR bands are slightly larger than the VIS/NIR bands, which are likely due to their high sensitivity to atmospheric conditions and relatively larger electronic crosstalk impact on the Terra instrument.

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Terra and Aqua MODIS collection 7 level 1B algorithm

Angal

Xiong

Chang

et al. 2022

J. Appl. Rem. Sens.

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Characterization of the on-orbit response versus scan angle for Terra MODIS SWIR bands in Collection 7

Cited by 4 publications

References 23 publications

Impact of satellite orbit drift on MODIS Earth scene observations used in calibration of the reflective solar bands

Impact of satellite orbit drift on MODIS Earth scene observations used in calibration of the reflective solar bands

Assessment of the Radiometric Calibration Consistency of Reflective Solar Bands between Terra and Aqua MODIS in Upcoming Collection-7 L1B

Terra and Aqua MODIS collection 7 level 1B algorithm

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