Initial on-orbit radiometric calibration of the Suomi NPP VIIRS reflective solar bands

Lei, Ning; Wang, Zhipeng; Fulbright, Jon P.; Lee, Shihyan; McIntire, Jeff; Chiang, K.; Xiong, Xiaoxiong

doi:10.1117/12.930486

Cited by 36 publications

(24 citation statements)

References 5 publications

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“…It was later identified that the wavelength dependent optics degradation was caused by the RTA mirror contamination [13][14][15] . Illustrated in Figure 10 (left) is an example of VIIRS sensor response trending for bands M1-M5 and M7.…”

Section: Optics Degradationmentioning

confidence: 98%

“…This degradation is wavelength, mirror side, and mirror scan-angle dependent [7][8] . Due to coating contamination, VIIRS rotating telescope assembly (RTA) mirrors have experienced more degradation in the NIR and SWIR spectral region [13][14][15] . Because of this wavelength-dependent optics degradation, the sensor's relative spectral response (RSR) or spectral response function (SRF), combined with in-band (IB) and out-of-band (OOB) responses, needs to be adjusted or modulated.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Optics Degradationmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Improvements of VIIRS and MODIS solar diffuser and lunar calibration

et al. 2013

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“…Similar to (5), we have the following equation which relates the BRDF degradation factor at a later orbit 2 t with its value at an earlier orbit 1 t only use half-angle-mirror (HAM) side A, high gain stage for dual gain bands, and mid-detector for each band (detector 8 for the M-bands and 16 for the I-bands). In the equation, B λ indicates the central wavelength of the band, B indicates a particular band, RVS is the relative reflectivity of the HAM (side A) 12 , RTA H is the BRDF degradation factor at the RTA SD view angle, and F is the detector F-factor 13,14 . As we did in the last section, we select t 1 that is small enough so that the SD BRDF degradation factor is angle independent.…”

Section: Sd Brdf Degradation Factor Angular Dependence Determined Fromentioning

confidence: 99%

Examination of the angular dependence of the SNPP VIIRS solar diffuser BRDF degradation factor

2014

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Modern Earth-orbiting Earth-observing remote sensing sensors often use onboard solar diffusers (SD) to calibrate their reflective solar bands (RSB), such as the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (SNPP) satellite. The SD's optical scattering property is measured by a bidirectional reflectance distribution function (BRDF). Once on orbit, the BRDF is found to degrade over time and the degradation factor is determined by, in the case of the SNPP VIIRS, an onboard solar diffuser stability monitor (SDSM) which observes the SD at a fixed view angle (relative to the SD surface). The SNPP VIIRS RSB however, observes the SD at a different angle. It is conventionally assumed (for cases like VIIRS) that the angular dependence of the BRDF degradation factor is negligible and hence the degradation factor determined by the SDSM is used to calibrate the RSB. We examine the angular dependence of the SNPP VIIRS SD BRDF degradation factor. We find that the degradation factor is clearly angle dependent when the SD BRDF degrades enough (< 0.98), and the larger the degradation the stronger the dependency.

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“…At each scan, data were collected at all three calibration views. The TEB are calibrated per scan with the BB source, and the RSBs are calibrated once per orbit over the South Pole when the SD is fully illuminated [15]. The SD source is monitored by the onboard Solar Diffuser Stability Monitor to track changes in the SD reflectivity [16].…”

Section: B Obcsmentioning

confidence: 99%

A New Method for Suomi-NPP VIIRS Day–Night Band On-Orbit Radiometric Calibration

Lee

McIntire

Oudrari

et al. 2015

IEEE Trans. Geosci. Remote Sensing

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The Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (S-NPP VIIRS) instrument contains a visible imaging band designed to produce imagery during both daytime and nighttime, which is called the day-night band (DNB). The DNB is a three-gain-stage backside-illuminated charge-coupled device (CCD) with four detector arrays that aggregate the individual CCD pixels into 32 different aggregation modes across scan, yielding imagery with a roughly constant horizontal sampling interval. The highest gain stage is over 100 000 times more sensitive than the lowest gain stage; the combination of the three gain stages allows for imagery with radiances ranging from 10 −10 to 10 −2 W · cm −2 · sr −1 . The initial DNB on-orbit calibration relies on monthly sensor special operations. This offline calibration approach results in discrete calibration and the loss of some science data. In this paper, we will present a new calibration method based solely on VIIRS onboard calibrators (OBCs). The calibrator data collected on the nighttime side of an orbit are used to determine the dark offset and the data collected over the daytime side of the orbit, and the day-night terminators are used to compute the cross-stage gain ratios. The results showed that the dark offset and the gain ratio derived from the initial method could be biased up to ten digital numbers (DN) and 12%, respectively, due to nighttime airglow and Earth scene stray light. The calibration is also continuous as calibrator data are recorded for each scan. Because no special operation and offline analysis are required, this method was approved for VIIRS operational implementation to improve the DNB radiometric calibration and sensor on-orbit operations.

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Initial on-orbit radiometric calibration of the Suomi NPP VIIRS reflective solar bands

Cited by 36 publications

References 5 publications

Improvements of VIIRS and MODIS solar diffuser and lunar calibration

Improvements of VIIRS and MODIS solar diffuser and lunar calibration

Examination of the angular dependence of the SNPP VIIRS solar diffuser BRDF degradation factor

A New Method for Suomi-NPP VIIRS Day–Night Band On-Orbit Radiometric Calibration

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