On-orbit performance of MODIS solar diffuser stability monitor

Xiong, Xiaoxiong; Angal, Amit; Choi, Taeyoung; Sun, Junqiang; Johnson, Eric H.

doi:10.1117/12.930963

Cited by 15 publications

(15 citation statements)

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“…Both MODIS and VIIRS are designed and built by the same instrument vendor. As expected, lessons from MODIS SD/SDSM design and operation have led to improvements for the VIIRS SD/SDSM system [8][9] . VIIRS RSB calibration approaches are similar to MODIS.…”

Section: Introductionmentioning

confidence: 86%

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Assessment of MODIS and VIIRS solar diffuser on-orbit degradation

et al. 2015

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Both MODIS and VIIRS instruments use a solar diffuser (SD) for their reflective solar bands (RSB) on-orbit calibration. On-orbit changes in SD bi-directional reflectance factor (BRF) are tracked by a solar diffuser stability monitor (SDSM) using its alternate measurements of the sunlight reflected off the SD panel and direct sunlight through a fixed attenuation screen. The SDSM calibration data are collected by a number of filtered detectors, covering wavelengths from 0.41 to 0.94 m. In this paper we describe briefly the Terra and Aqua MODIS and S-NPP VIIRS SDSM on-orbit operation and calibration activities and strategies, provide an overall assessment of their SDSM on-orbit performance, including wavelength-dependent changes in the SDSM detector responses and changes in their SD BRF, and discuss remaining challenging issues and their potential impact on RSB calibration quality. Due to different launch dates, operating configurations, and calibration frequencies, the Terra and Aqua MODIS and S-NPP VIIRS SD have experienced different amount of SD degradation. However, in general the shorter the wavelength, the larger is the SD on-orbit degradation. On the other hand, the larger changes in SDSM detector responses are observed at longer wavelengths in the near infrared (NIR).

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Section: Introductionmentioning

confidence: 86%

“…The large ripples in MODIS SDSM Sun view responses are not present in VIIRS SDSM's Sun view observations. Therefore, no normalization approach is needed even at the mission beginning to track SD degradation at each detector wavelength [8][9]14 .…”

Section: Sdsm On-orbit Operationmentioning

confidence: 99%

Assessment of MODIS and VIIRS solar diffuser on-orbit degradation

et al. 2015

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“…The SDSM is operated during each scheduled SD calibration event. It collects and compares alternate measurements of the sunlight reflected from the SD and that directly through an attenuation screen [11]. Figure 2 is a schematic for MODIS RSB on-orbit calibration.…”

Section: On-orbit Calibration and Lunar Observationsmentioning

confidence: 99%

Comparison of MODIS and PLEIADES Lunar observations

et al. 2014

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MODIS is the key instrument for the NASA's EOS Terra and Aqua missions, launched in late 1999 and early 2002, respectively. MODIS has 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). MODIS RSB are calibrated on-orbit using an on-board solar diffuser and regularly scheduled lunar observations. For each instrument, the scheduled lunar observations are made through its space view (SV) port at nearly identical lunar phase angles via spacecraft roll maneuvers. Occasionally, unscheduled lunar observations at different phase angles are also collected by both Terra and Aqua MODIS. The PLEIADES system is composed of two satellites, PLEIADES-1A launched at the end of 2011 and PLEIADES-1B a year later. The PLEIADES has 5 reflective solar bands or channels (blue, green, red, nearinfrared, and panchromatic) that are calibrated on-orbit using observations of Pseudo Invariant Calibration Sites (PICS). Since launch, more than 1000 lunar images covering the phase angle range of ±115⁰ have been acquired by PLEIADES-1B for its on-orbit calibration and sensitivity study of lunar calibration methods. This paper provides an overview of MODIS and PLEIADES lunar observations and an assessment of their calibration difference based on lunar observations made over a range of phase angles. Also discussed in this paper are strategies and future effort that could potentially benefit other earth observing sensors and improve the calibration accuracy and consistency of existing lunar model(s).

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“…From Figure 5, it is obvious that the SDSM Sun view response trending has a strong wavelength-dependent feature for both MODIS and VIIRS. This wavelength dependent response degradation, larger at longer (NIR) wavelengths, is likely due to on-orbit displacement damage to the detectors by the high-energy protons in the space environment 22 . Because of its wavelength-dependence, this degradation could affect the RSR of SDSM detectors and potentially impact the accuracy to track SD on-orbit degradation.…”

Section: Sdsm Detector Degradationmentioning

confidence: 99%

Improvements of VIIRS and MODIS solar diffuser and lunar calibration

et al. 2013

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Both VIIRS and MODIS instruments use solar diffuser (SD) and lunar observations to calibrate their reflective solar bands (RSB). A solar diffuser stability monitor (SDSM) is used to track the SD on-orbit degradation. On-orbit observations have shown similar wavelength-dependent SD degradation (larger at shorter VIS wavelengths) and SDSM detector response degradation (larger at longer NIR wavelengths) for both VIIRS and MODIS instruments. In general, the MODIS scan mirror has experienced more degradation in the VIS spectral region whereas the VIIRS rotating telescope assembly (RTA) mirrors have seen more degradation in the NIR and SWIR spectral region. Because of this wavelength dependent mirror degradation, the sensor's relative spectral response (RSR) needs to be modulated. Due to differences between the solar and lunar spectral irradiance, the modulated RSR could have different effects on the SD and lunar calibration. In this paper, we identify various factors that should be considered for the improvements of VIIRS and MODIS solar and lunar calibration and examine their potential impact. Specifically, we will characterize and assess the calibration impact due to SD and SDSM attenuation screen transmission (uncertainty), SD BRF uncertainty and onorbit degradation, SDSM detector response degradation, and modulated RSR resulting from the sensor's optics degradation. Also illustrated and discussed in this paper are the calibration strategies implemented in the VIIRS and MODIS SD and lunar calibrations and efforts that could be made for future improvements.

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On-orbit performance of MODIS solar diffuser stability monitor

Cited by 15 publications

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Assessment of MODIS and VIIRS solar diffuser on-orbit degradation

Assessment of MODIS and VIIRS solar diffuser on-orbit degradation

Comparison of MODIS and PLEIADES Lunar observations

Improvements of VIIRS and MODIS solar diffuser and lunar calibration

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