Dr. Changyong Cao Profile

Dr. Changyong Cao

Physical Scientist at NESDIS

SPIE Involvement:

Conference Co-Chair | Author | Editor

Publications (110)

SPIE Journal Paper | 4 September 2023 Open Access

Post-launch evaluation and improvements of National Oceanic and Atmospheric Administration-20 Visible-Infrared Imaging Radiometer Suite sensor data record geolocation accuracy

Slawomir Blonski, Wenhui Wang, Khalil Ahmad, Changyong Cao

JARS, Vol. 17, Issue 03, 034506, (September 2023) https://doi.org/10.1117/12.10.1117/1.JRS.17.034506

KEYWORDS: Matrices, Satellites, Ocean optics, Space operations, Equipment, Error analysis, Calibration, Landsat, Radiometry, Meteorological satellites

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National Oceanic and Atmospheric Administration (NOAA)-20 (formerly Joint Polar Satellite System-1) is a polar-orbiting weather satellite launched on November 18, 2017. Visible-Infrared Imaging Radiometer Suite (VIIRS) is one of five instruments onboard NOAA-20 (N20), and it jointed on orbit the previous VIIRS instrument operating on the Suomi NPP (SNPP) spacecraft since November 2011. During post-launch testing, the accuracy of VIIRS sensor data record (SDR) geolocation products was evaluated using a system called ground control point matching. The control points are based on 30-m Landsat images as “ground truth,” and the matchups employ their cross-correlation with the 375-m VIIRS images in band I1. Initial N20 VIIRS geolocation errors shortly after launch exceeded 2 km and were somewhat larger than those previously observed for SNPP VIIRS. The optimization of processing parameters successfully reduced the geolocation uncertainty to less than 400 m (at nadir, 3-sigma), which is comparable to the current performance for the SNPP VIIRS SDR products, with the majority of the geolocation errors within 200 m. The improvement was achieved by adjusting only the instrument-to-spacecraft rotation angles (the “mounting matrix”). Although the uncertainty evaluation was based on global matchups collected over 12-month periods, the parameter optimization was based on a reduction of the geolocation angular errors by reprocessing VIIRS SDR and re-analyzing the global matchups from 16-day orbit repeat periods. Geolocation of the 750-m day/night band (DNB), which is not co-registered with the 375-m I-bands and the 750-m M-bands, was evaluated and optimized separately, using the correlation between DNB and the I1 band re-projected images. Initial N20 VIIRS DNB geolocation errors were even larger than those observed for the other bands, but they were also successfully reduced by adjusting DNB-specific processing parameters. The initial improvements in the N20 VIIRS geolocation accuracy were achieved in 2018, and the processing parameters were further refined after an optical model correction in 2021.

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SPIE Journal Paper | 21 July 2022 Open Access

Validation of geostationary operational environmental satellite-16 advanced baseline imager radiometric calibration with airborne field campaign data and reanalysis of north-south scan data

Xi Shao, Francis Padula, Changyong Cao, Xiangqian Wu, Fangfang Yu, Aaron Pearlman, Haifeng Qian, Sirish Uprety, Taeyoung Choi

JARS, Vol. 16, Issue 03, 037501, (July 2022) https://doi.org/10.1117/12.10.1117/1.JRS.16.037501

KEYWORDS: Sensors, Calibration, Satellites, Detection and tracking algorithms, Diffusers, Target detection, Sensor performance, Detector arrays, Reflectivity, Algorithm development

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Proceedings Article | 3 August 2021 Paper

S-NPP/NOAA-20 VIIRS reflective solar bands on-orbit calibration bias investigation

D. Moyer, S. Uprety, W. Wang, C. Cao, I. Guch

Proceedings Volume 11829, 1182912 (2021) https://doi.org/10.1117/12.2595175

KEYWORDS: Reflectivity, Sensors, Calibration, Transmittance, Sun, Diffusers, MODIS, Lamps, Bidirectional reflectance transmission function, Manufacturing

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Proceedings Article | 1 August 2021 Presentation + Paper

Restoration of degraded Suomi-NPP VIIRS DNB nighttime imagery induced by electronic bias change

Yalong Gu, Slawomir Blonski, Xi Shao, Sirish Uprety, Changyong Cao

Proceedings Volume 11829, 118290V (2021) https://doi.org/10.1117/12.2593739

KEYWORDS: Calibration, Sensors, Image quality, Charge-coupled devices, Satellites, CCD image sensors, Algorithm development

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SPIE Journal Paper | 26 February 2021 Open Access

Characterization and monitoring of GOES-16 ABI stray light and comparison with Himawari-8 AHI and GOES-17 ABI

Xi Shao, Xiangqian Wu, Fangfang Yu, Changyong Cao

JARS, Vol. 15, Issue 01, 017503, (February 2021) https://doi.org/10.1117/12.10.1117/1.JRS.15.017503

KEYWORDS: Stray light, Sun, Contamination, Sensors, Satellites, Infrared imaging, Imaging systems, Satellite imaging, Earth's atmosphere, Stray light analysis

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SPIE Journal Paper | 30 September 2020 Open Access

Special Section Guest Editorial: Instrument Calibration and Product Validation of GOES-R

Xiangqian Wu, Changyong Cao, Satya Kalluri, Jaime Daniels

JARS, Vol. 14, Issue 03, 032401, (September 2020) https://doi.org/10.1117/12.10.1117/1.JRS.14.032401

KEYWORDS: Calibration, Satellites, Sensors, Imaging systems, Aerospace engineering, Modulation transfer functions, X-rays, X-ray imaging, Ultraviolet radiation, Surveillance

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Proceedings Article | 9 September 2020 Presentation + Paper

Radiometric performance characterization of NOAA-20 VIIRS reflective solar bands

Sirish Uprety, Changyong Cao, Xi Shao

Proceedings Volume 11501, 1150115 (2020) https://doi.org/10.1117/12.2568721

KEYWORDS: Reflectivity, Calibration, Sensors, Photonic integrated circuits, Satellites

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NOAA-20 VIIRS Reflective Solar Bands (RSBs) have been performing well since launch with good quality sensor data records (SDRs). The radiometric performance of these SDRs have been continuously analyzed and monitored using various independent validation techniques. It is important to maintain radiometric consistency between NOAA-20 VIIRS SDRs and other well calibrated instruments such as S-NPP VIIRS for long term environmental applications. Past studies have shown that there exists a near consistent bias in RSBs between the two VIIRS instruments, with NOAA-20 VIIRS top-of-atmosphere (TOA) reflectance being lower by nearly 2-3%. It is crucial to monitor the radiometric consistency between the two VIIRS instruments and help the user community understand the trending of the relative bias between two VIIRS and its impacts on the higher level EDR products. This study is focused on analyzing NOAA-20 VIIRS radiometric bias relative to S-NPP VIIRS operational SDR using different techniques such as the pseudo-invariant calibration sites (PICS) and inter-comparison with other satellite instruments using Simultaneous Nadir Overpasses (SNOs). The impact on bias due to spectral differences between the two VIIRS instruments is quantified using hyperspectral measurements from Sciamachy. Since S-NPP VIIRS is used as a reference, any residual degradation in its operational calibration since 2018 needs to be accounted. The correction for residual degradation will be performed in future for more accurate NOAA-20 VIIRS bias trending once the S-NPP VIIRS reprocessing is completed to the more recent date. The study suggests that NOAA-20 VIIRS reflective solar bands are consistently lower in reflectance than that from S-NPP VIIRS by about 2-3% for most bands. Larger bias is observed for bands M5 (0.67 μm) and M7 (0.86 μm) bands mainly because S-NPP VIIRS absolute calibration for these bands is biased high by about 2%. NOAA-20 VIIRS bias values estimated in this study are consistent with the past studies. The bias remains nearly constant for all the bands. Thus, the study also uses the trend-corrected S-NPP VIIRS data to quantify NOAA-20 VIIRS temporal radiometric bias. Due to shorter span of time for NOAA-20 VIIRS, i.e. ~ two years in orbit, analyzing its radiometric stability using calibration sites is more challenging and results in higher uncertainty. This study uses Libya 4 calibration site to further analyze and validate the radiometric.

Proceedings Article | 20 August 2020 Presentation + Paper

Update on SNPP and NOAA-20 VIIRS day/night band stray light correction

Xi Shao, Sirish Uprety, Yalong Gu, Slawomir Blonski, Changyong Cao

Proceedings Volume 11501, 1150110 (2020) https://doi.org/10.1117/12.2568055

KEYWORDS: Stray light, Calibration, Sensors, Satellites, Image quality, Detection and tracking algorithms, Space operations, Satellite imaging, Diffusers

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Proceedings Article | 20 August 2020 Presentation + Paper

Correction of NOAA-20 VIIRS day/night band low-gain stage gain calibration errors by scaling factors derived from prelaunch testing data

Yalong Gu, Slawomir Blonski, Wenhui Wang, Taeyoung Choi, Sirish Uprety, Xi Shao, Changyong Cao

Proceedings Volume 11501, 115010Y (2020) https://doi.org/10.1117/12.2568783

KEYWORDS: Calibration, Sensors, Sun, Satellites, Diffusers, Stray light, Visible radiation, Satellite imaging, Radiometry

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SPIE Journal Paper | 29 May 2020

Radiometric consistency between GOES-16 ABI and VIIRS on Suomi NPP and NOAA-20

Sirish Uprety, Changyong Cao, Xi Shao

JARS, Vol. 14, Issue 03, 032407, (May 2020) https://doi.org/10.1117/12.10.1117/1.JRS.14.032407

KEYWORDS: Calibration, Reflectivity, Clouds, Satellites, Sensors, Sun, Photonic integrated circuits, Bidirectional reflectance transmission function, Imaging systems, MODIS

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Proceedings Article | 9 September 2019 Presentation + Paper

NOAA-20 VIIRS initial on-orbit radiometric calibration using scheduled lunar observations

Taeyoung Choi, Xi Shao, Slawomir Blonski, Wenhui Wang, Sirish Uprety, Changyong Cao

Proceedings Volume 11127, 111271Z (2019) https://doi.org/10.1117/12.2528459

KEYWORDS: Calibration, Sensors, Satellites, Sun, Transmittance, Bidirectional reflectance transmission function

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Proceedings Article | 9 September 2019 Presentation + Paper

Correction of detector nonlinearity induced striping in VIIRS day/night band nighttime imagery

Yalong Gu, Sirish Uprety, Xi Shao, Slawomir Blonski, Wenhui Wang, Changyong Cao

Proceedings Volume 11127, 111271T (2019) https://doi.org/10.1117/12.2528025

KEYWORDS: Sensors, Calibration, Satellite imaging, Visible radiation, Nonlinear response

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Proceedings Article | 9 September 2019 Paper

Modeling spectral degradation of MODIS and VIIRS solar diffusers

Xi Shao, Tung-Chang Liu, Xiaoxiong Xiong, Changyong Cao, Taeyoung Choi, Amit Angal

Proceedings Volume 11127, 111271S (2019) https://doi.org/10.1117/12.2528442

KEYWORDS: MODIS, Reflectivity, Surface roughness, Calibration, Solar radiation models, Data modeling, Solar radiation, Spectral models, Light scattering, Diffusers

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Proceedings Article | 9 September 2019 Paper

Physical modeling of NOAA-20 VIIRS solar diffuser stability monitor sun view screen transmittance

Xi Shao, Taeyoung Choi, Changyong Cao, Tung-Chang Liu, Slawomir Blonski, Sirish Uprety, Bin Zhang

Proceedings Volume 11127, 111271R (2019) https://doi.org/10.1117/12.2528460

KEYWORDS: Sun, Transmittance, Calibration, Reflectivity, Satellites, Sensors, Systems modeling, 3D modeling, Diffusers, Computer simulations

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Proceedings Article | 9 September 2019 Presentation + Paper

Geo-Leo intercalibration to evaluate the radiometric performance of NOAA-20 VIIRS and GOES-16 ABI

Sirish Uprety, Changyong Cao, Xi Shao

Proceedings Volume 11127, 111270S (2019) https://doi.org/10.1117/12.2528468

KEYWORDS: Calibration, Reflectivity, Sensors, Clouds, Satellites, Diffusers, Imaging systems, Factor analysis, Sensor performance

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Proceedings Article | 19 November 2018 Paper

NOAA-20 VIIRS on-orbit performance, data quality, and operational Cal/Val support

Changyong Cao, Slawomir Blonski, Wenhui Wang, Sirish Uprety, Xi Shao, Jason Choi, Erin Lynch, Satya Kalluri

Proceedings Volume 10781, 107810K (2018) https://doi.org/10.1117/12.2324329

KEYWORDS: Calibration, Signal to noise ratio, Infrared radiation, Long wavelength infrared, Diffusers, Infrared imaging, Reflectivity, Sensors, Satellites, MODIS

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Proceedings Article | 13 November 2018 Paper

Initial assessment of radiometric performance of N20 VIIRS reflective solar bands using vicarious approaches

A. Wu, T. Chang, X. Xiong, C. Cao

Proceedings Volume 10781, 107810W (2018) https://doi.org/10.1117/12.2324756

KEYWORDS: Reflectivity, MODIS, Bidirectional reflectance transmission function, Calibration, Sensors, Satellites, Near infrared, Domes, Visible radiation, Diffusers

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Proceedings Article | 23 October 2018 Paper

Traceability and consistency of COSMIC radio occultation in comparison with NOAA-20 CrIS infrared sounder observations

Changyong Cao, Erin Lynch, Bin Zhang

Proceedings Volume 10781, 107810U (2018) https://doi.org/10.1117/12.2324331

KEYWORDS: Satellite navigation systems, Satellites, Infrared radiation, Receivers, Calibration, Black bodies, Clocks, Temperature metrology, Transmitters, Atmospheric modeling

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The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite system for the Radio Occultation (RO) mission provides advances in meteorology, ionospheric research, climatology, and space weather by utilizing the readily available Global Navigation Satellite System (GNSS) signals in conjunction with GNSS receivers in low Earth orbiting (LEO) satellites. COSMIC was launched in 2006 with six satellites in a constellation known as FORMOSAT-3 in low inclination orbits to provide global coverage. RO relies on the calculation of GNSS signal time delay in carrier phase due to the atmosphere in the L1 and L2 signals transmitted between the GNSS and receiving satellites in the LEO orbit, from which the bending angle, refractivity, and atmospheric profiles can be retrieved. Since the Atomic Frequency Standard (AFS) based GNSS signal is International System of Units (SI) traceable, is actively maintained, and the precise orbit of both the GNSS and the LEO satellites can be determined accurately, RO data from COSMIC have been recognized as stable references for data assimilation (DA) in Numerical Weather Prediction (NWP) models. Currently, NWP customers are eager to obtain similar data from COSMIC2 which will be launched in the next few months to mitigate the aging COSMIC constellation and diminishing number of ROs.

Meanwhile, the calibration of the hyperspectral sounders such as Cross-track Infrared Sounder (CrIS) on NOAA-20 relies on a high quality onboard blackbody which is also traceable to SI through prelaunch characterization relating to the laboratory blackbody with traceable calibration to NIST, and hyperspectral sounders have been recognized as onorbit calibration references for other broad- or narrow-band infrared (IR) observations. In this paper we analyze the traceability of both systems in their raw measurements as well as retrieved geophysical variables. Comparisons are also made in spectral radiance/brightness temperature derived from the two systems. The objective is to gain a better understanding of the different paths of traceability to SI and ensure the consistency of the products for numerical weather prediction and other applications. This study directly supports the COSMIC2 verification and validation, as well as postlaunch calibration/validation of NOAA-20 CrIS.

Proceedings Article | 23 October 2018 Paper

Evaluating NOAA-20 and S-NPP VIIRS radiometric consistency

Sirish Uprety, Changyong Cao, Slawomir Blonski, Xi Shao

Proceedings Volume 10781, 107810V (2018) https://doi.org/10.1117/12.2324464

KEYWORDS: MODIS, Calibration, Diffusers, Bidirectional reflectance transmission function, Satellites, Radiometry

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Proceedings Article | 23 October 2018 Paper

Characterization and correction of stray light for NOAA-20 VIIRS day/night band

Xi Shao, Changyong Cao, Tung-Chang Liu, Sirish Uprety, Bin Zhang, Wenhui Wang, Slawomir Blonski

Proceedings Volume 10781, 107810H (2018) https://doi.org/10.1117/12.2323981

KEYWORDS: Stray light, Sensors, Space operations, Satellites, Diffusers, Contamination, Charge-coupled devices, CCD image sensors, Auroras, Calibration

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Proceedings Article | 25 September 2018 Paper

Improving NOAA 20 VIIRS screen transmittance and solar diffuser BRF estimation from both Yaw maneuver and regular on-orbit data

Taeyoung Choi, Slawomir Blonski, Xi Shao, Changyong Cao

Proceedings Volume 10785, 1078516 (2018) https://doi.org/10.1117/12.2324335

KEYWORDS: Sensors, Sun, Transmittance, Calibration, Diffusers, Reflectivity, Bidirectional reflectance transmission function, Satellite imaging, Satellites, Radiometry

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Proceedings Article | 25 September 2018 Presentation + Paper

Post-launch evaluation and improvements of NOAA-20 VIIRS geolocation accuracy

Slawomir Blonski, Wenhui Wang, Changyong Cao

Proceedings Volume 10785, 1078518 (2018) https://doi.org/10.1117/12.2325176

KEYWORDS: Space operations, Calibration, Sensors, Satellites, Earth observing sensors, Landsat, Error analysis, Meteorological satellites, Stars, Geodesy

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Proceedings Article | 7 September 2018 Presentation + Paper

Independent validation of the advanced baseline imager (ABI) on NOAA's GOES-16: post-launch ABI airborne science field campaign results

Brent Bartlett, Jason Casey, Francis Padula, Aaron Pearlman, Dave Pogorzala, Changyong Cao

Proceedings Volume 10764, 107640H (2018) https://doi.org/10.1117/12.2323672

KEYWORDS: Sensors, Databases, Spectrometers, Imaging systems, Calibration, Reflectivity, Image segmentation, Atmospheric corrections, Image processing, Space operations

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Proceedings Article | 7 September 2018 Paper

NOAA-20 VIIRS radiometric band saturation evaluation and comparison with Suomi NPP VIIRS using global probability distribution function method

Bin Zhang, Changyong Cao, Sirish Uprety, Xi Shao

Proceedings Volume 10764, 107641Q (2018) https://doi.org/10.1117/12.2321971

KEYWORDS: Sensors, Stray light, Clouds, Calibration, Satellites, Aerosols

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NOAA-20 was successfully launched on Nov. 18, 2017. Intensive radiometric calibration and validation activities for VIIRS onboard NOAA-20 were carried out immediately after the sensor data become available. Several bands of NOAA-20 VIIRS such as M6, and M8 have maximum dynamic range requirements or waivers on the saturation value and require post-launch assessment of the impacts on the L1B (or EDR) products. Since the saturation threshold in data processing is defined as the measured Digital Number (DN) count, the corresponding saturation radiance value in the L1B data product can vary due to detector difference and degradation in the sensor optical throughput. On the other hand, users of L1B data care more about the accuracy of scene-dependent radiance value and the impact of detector saturation on the radiance data. In order to validate the detector saturation level and assess their impacts on the radiance data products, histogram-based Probability Distribution Function (PDF) is derived both at detector level and at band level from the daily global radiance data. With such distribution function, the saturation level in radiance can be identified from the sharp fold-over and cut-off at the high radiance value in the distribution. In addition, the percentage of the affected pixels in the global data can be quantified and the detector performance can be compared. Since NOAA- 20 and SNPP are 50 minutes apart in the same orbital plane and have the same equator-crossing time, the probability distribution function method also enables comparison of the radiometric calibration performance between the two sensors. For example, the saturation radiance value for VIIRS M6 on NOAA-20 is ~44.2 (W/m²-sr-um) on 01/11/2018, which is ~26% lower than that of SNPP VIIRS. Such difference can be traced to the more rapid degradation of rotating telescope assembly mirror reflectance in SNPP VIIRS. In addition to saturation analysis, the PDF method allows us to analyze the VIIRS Day/Night Band (DNB) according to the solar zenith angle range, and the performance of stray light correction can be compared between SNPP and NOAA-20 as well.

Proceedings Article | 7 September 2018 Presentation + Paper

Characterization of GOES-16 ABI detector-level uniformity from post-launch north south scan collections of several earth targets

Jason Casey, Francis Padula, Monica Cook, Brent Bartlett, Aaron Pearlman, Dave Pogorzala, Changyong Cao

Proceedings Volume 10764, 107640D (2018) https://doi.org/10.1117/12.2323673

KEYWORDS: Sensors, Target detection, Calibration, Imaging systems, Staring arrays, Sensor performance, Image sensors, Mirrors, Image processing, Data processing

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Proceedings Article | 7 September 2018 Presentation + Paper

Initial on-orbit radiometric calibration of the NOAA-20 VIIRS Reflective Solar Bands

Taeyoung Choi, Slawomir Blonski, Changyong Cao

Proceedings Volume 10764, 107641B (2018) https://doi.org/10.1117/12.2321752

KEYWORDS: Calibration, Sensors, Sun, Reflectivity, Transmittance, Satellites, Diffusers, Infrared imaging, Infrared radiation, Radiometry

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Proceedings Article | 7 September 2018 Paper

Orbital variations and impacts on observations from SNPP, NOAA 18-20, and AQUA sun-synchronous satellites

Xi Shao, Changyong Cao, Xiaoxiong Xiong, Tung-chang Liu, Bin Zhang, Sirish Uprety

Proceedings Volume 10764, 107641U (2018) https://doi.org/10.1117/12.2323012

KEYWORDS: Satellites, MODIS, Temperature metrology, Visible radiation, Infrared imaging, Radiometry, Environmental monitoring, Earth observing sensors, Sensors, Weather forecasting

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Proceedings Article | 7 September 2018 Presentation + Paper

An improved algorithm for VIIRS Day/Night Band (DNB) high gain stage (HGS) dark offset determination

Yalong Gu, Sirish Uprety, Slawormir Blonski, Bin Zhang, Changyong Cao

Proceedings Volume 10764, 107641J (2018) https://doi.org/10.1117/12.2322923

KEYWORDS: Sensors, Calibration, Airglow, Detection and tracking algorithms, Charge-coupled devices, Satellites

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Proceedings Article | 7 September 2018 Paper

Validation of GOES-16 ABI reflective solar band calibration through reanalysis and comparison with field campaign data

Xi Shao, Xiangqian Wu, Changyong Cao, Sirish Uprety, Fangfang Yu, Haifeng Qian, Frank Padula, Aaron Pearlman, Taeyoung Choi, Brent Bartlett, Jason Casey

Proceedings Volume 10764, 107640I (2018) https://doi.org/10.1117/12.2323024

KEYWORDS: Sensors, Calibration, Reflectivity, Detection and tracking algorithms, Data conversion, Diffusers, Detector arrays, Data modeling, Spatial resolution, Mirrors

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Proceedings Article | 7 September 2018 Paper

A light contamination ranking index-based method for automating VIIRS day/night band stray light correction

Xi Shao, Tung-Chang Liu, Sirish Uprety, Wenhui Wang, Bin Zhang, Changyong Cao

Proceedings Volume 10764, 107641I (2018) https://doi.org/10.1117/12.2322999

KEYWORDS: Stray light, Contamination, Sensors, Auroras, Diffusers, Light, Image processing, Calibration, Satellites

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Proceedings Article | 29 September 2017 Presentation + Paper

Near-nadir scan overlap in Earth observations from VIIRS and MODIS

Slawomir Blonski, Changyong Cao

Proceedings Volume 10423, 1042312 (2017) https://doi.org/10.1117/12.2278440

KEYWORDS: MODIS, Satellites, Data modeling, Mirrors, Telescopes, Satellite imaging, Scanners, Radiometry, Radio optics, Space operations

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Proceedings Article | 29 September 2017 Paper

Assessment of stability of the response versus scan angle for the S-NPP VIIRS reflective solar bands using pseudo-invariant desert and Dome C sites

Aisheng Wu, Xiaoxiong Xiong, Changyong Cao

Proceedings Volume 10423, 1042322 (2017) https://doi.org/10.1117/12.2278380

KEYWORDS: Reflectivity, Calibration, Bidirectional reflectance transmission function, Domes, MODIS, Sensors, Mirrors, Diffusers, Black bodies, Data modeling

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Proceedings Article | 21 September 2017 Presentation

Validation of VIIRS with CrIS by taking into account the sub-pixel cloudiness and viewing geometry (Conference Presentation)

Jun Li, Changyong Cao, Zhenglong Li, Xinya Gong, Wenhui Wang, Christopher Moeller

Proceedings Volume 10402, 1040224 (2017) https://doi.org/10.1117/12.2273027

KEYWORDS: Infrared imaging, Clouds, Infrared radiation, Calibration, Infrared sensors, Visible radiation, Radiometry, Sensors, Imaging systems, Sensor calibration

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Proceedings Article | 5 September 2017 Presentation + Paper

Suomi-NPP VIIRS initial reprocessing improvements and validations in the reflective solar bands (RSBs)

Taeyoung Choi, Junqiang Sun, Bin Zhang, Zhuo Wang, Changyong Cao, Fuzhong Weng, Menghua Wang

Proceedings Volume 10402, 104021V (2017) https://doi.org/10.1117/12.2274081

KEYWORDS: Calibration, Reflectivity, Visible radiation, Infrared imaging, Radiometry, Sensors, Infrared sensors, Remote sensing, Data processing, Satellites

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Proceedings Article | 5 September 2017 Presentation + Paper

Monitoring of VIIRS ocean clear-sky brightness temperatures against CRTM simulation in ICVS for TEB/M bands

Xingming Liang, Ninghai Sun, Alexander Ignatov, Quanhua Liu, Wenhui Wang, Bin Zhang, Fuzhong Weng, Changyong Cao

Proceedings Volume 10402, 104021S (2017) https://doi.org/10.1117/12.2273443

KEYWORDS: Calibration, Satellites, Data modeling, Sensors, Environmental monitoring, Infrared imaging, Radiative transfer, Atmospheric modeling, Computer simulations, System integration

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Proceedings Article | 5 September 2017 Paper

Operational correction and validation of the VIIRS TEB longwave infrared band calibration bias during blackbody temperature changes

Wenhui Wang, Changyong Cao, Alex Ignatov, Zhenglong Li, Likun Wang, Bin Zhang, Slawomir Blonski, Jun Li

Proceedings Volume 10402, 104021P (2017) https://doi.org/10.1117/12.2272377

KEYWORDS: Calibration, Black bodies, Sensors, Infrared radiation, Long wavelength infrared

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Proceedings Article | 30 August 2017 Paper

Preliminary study of the on-orbit radiometric traceability and artifacts for the VIIRS longwave infrared channels during blackbody temperature changes

Changyong Cao, Wenhui Wang, Slawomir Blonski, Bin Zhang

Proceedings Volume 10403, 104030F (2017) https://doi.org/10.1117/12.2272442

KEYWORDS: Calibration, Black bodies, Infrared radiation, Long wavelength infrared, Infrared technology, Temperature metrology, Thermography, Infrared sensors

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Proceedings Article | 19 October 2016 Presentation + Paper

Reprocessing VIIRS sensor data records from the early SNPP mission

Slawomir Blonski, Changyong Cao

Proceedings Volume 10000, 1000015 (2016) https://doi.org/10.1117/12.2241423

KEYWORDS: Calibration, Satellites, Sensors, Radiometry, Infrared sensors, Diffusers, Reflectivity, Telescopes, Short wave infrared radiation, Data acquisition

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Proceedings Article | 19 September 2016 Presentation + Paper

Influence of atmospheric turbulence on the visible infrared imaging radiometer suite (VIIRS) day/night band (DNB) low light calibration with ground based light source

Yalong Gu, Changyong Cao

Proceedings Volume 9972, 99721I (2016) https://doi.org/10.1117/12.2236527

KEYWORDS: Calibration, Light sources, Atmospheric propagation, Atmospheric turbulence, Scintillation, Light, Visible radiation, Radiometry, Satellites, Atmospheric modeling

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Proceedings Article | 19 September 2016 Presentation + Paper

S-NPP VIIRS thermal emissive band gain correction during the blackbody warm-up-cool-down cycle

Taeyoung Choi, Changyong Cao, Fuzhong Weng

Proceedings Volume 9972, 99721J (2016) https://doi.org/10.1117/12.2236995

KEYWORDS: Calibration, Black bodies, Visible radiation, Infrared imaging, Sensors, Temperature metrology, Satellites, MODIS, Critical dimension metrology, Reflectivity

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Proceedings Article | 19 September 2016 Presentation + Paper

Trade study of substituting VIIRS M10 with aggregated I3 to enable addition of a water vapor channel

Slawomir Blonski, Changyong Cao

Proceedings Volume 9972, 99721M (2016) https://doi.org/10.1117/12.2235938

KEYWORDS: Signal to noise ratio, Atmospheric modeling, Satellites, Meteorological satellites, Sensors, Diffusers, Staring arrays, Calibration, Long wavelength infrared, Quantization

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Proceedings Article | 19 September 2016 Presentation + Paper

Towards post-launch validation of GOES-R ABI SI traceability with high-altitude aircraft, small near surface UAS, and satellite reference measurements

Francis Padula, Aaron Pearlman, Changyong Cao, Steve Goodman

Proceedings Volume 9972, 99720V (2016) https://doi.org/10.1117/12.2238181

KEYWORDS: Imaging systems, Satellites, Calibration, Sensors, Environmental sensing, Staring arrays, Target detection, Data modeling, Data acquisition, Mirrors

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Proceedings Article | 19 September 2016 Presentation + Paper

Initial design and performance of the near surface unmanned aircraft system sensor suite in support of the GOES-R field campaign

Aaron Pearlman, Francis Padula, Xi Shao, Changyong Cao, Steven Goodman

Proceedings Volume 9972, 99720U (2016) https://doi.org/10.1117/12.2238178

KEYWORDS: Sensors, Satellites, Calibration, Spectrometers, Polarization, Reflectivity, Temperature metrology, Short wave infrared radiation, Radiative transfer, Lamps

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Proceedings Article | 19 September 2016 Presentation + Paper

Tracking on-orbit stability of the response versus scan angle for the S-NPP VIIRS reflective solar bands

Aisheng Wu, Xiaoxiong (Jack) Xiong, Changyong Cao

Proceedings Volume 9972, 99721C (2016) https://doi.org/10.1117/12.2238106

KEYWORDS: MODIS, Calibration, Reflectivity, Satellites, Diffusers, Sensors, Visible radiation, Calibration, MODIS, Mirrors, Radiometry, Temperature metrology

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Proceedings Article | 2 May 2016 Paper

Global space-based inter-calibration system reflective solar calibration reference: from Aqua MODIS to S-NPP VIIRS

Xiaoxiong Xiong, Amit Angal, James Butler, Changyong Cao, David Doelling, Aisheng Wu, Xiangqian Wu

Proceedings Volume 9881, 98811D (2016) https://doi.org/10.1117/12.2224320

KEYWORDS: Calibration, MODIS, Sensors, Reflectivity, Bidirectional reflectance transmission function, Sensor calibration, Diffusers, Sensor performance, Domes, Satellites

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Proceedings Article | 2 May 2016 Paper

On-orbit radiometric performance characterization of S-NPP VIIRS reflective solar bands

Sirish Uprety, Slawomir Blonski, Changyong Cao

Proceedings Volume 9881, 98811H (2016) https://doi.org/10.1117/12.2223788

KEYWORDS: Calibration, MODIS, Diffusers, Reflectivity, Sensors, Spatial resolution, Short wave infrared radiation, Mirrors, Scientific research, Clouds

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SPIE Journal Paper | 11 March 2016

Feasibility demonstration for calibrating Suomi-National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite day/night band using Dome C and Greenland under moon light

Shi Qiu, Xi Shao, Changyong Cao, Sirish Uprety

JARS, Vol. 10, Issue 01, 016024, (March 2016) https://doi.org/10.1117/12.10.1117/1.JRS.10.016024

KEYWORDS: Calibration, Reflectivity, Atmospheric modeling, Sensors, Bidirectional reflectance transmission function, Radiometry, Infrared imaging, Performance modeling, Visible radiation, Satellites

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Proceedings Article | 12 October 2015 Paper

Auroral activities observed by SNPP VIIRS day/night band during a long period geomagnetic storm event on April 29-30, 2014

Xi Shao, Changyong Cao, Tung-chang Liu, Bin Zhang, Wenhui Wang, Shing Fung

Proceedings Volume 9639, 963921 (2015) https://doi.org/10.1117/12.2193911

KEYWORDS: Auroras, Magnetism, Stray light, Solar processes, Sensors, Satellites, Electrons, Radiometry, Contamination, CCD image sensors

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The Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance that can span 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. When the satellite passes through the day-night terminator, the DNB sensor is affected by stray light due to solar illumination on the instrument. With the implementation of stray light correction, stray light-corrected DNB images enable the observation of aurora occurred in the high latitude regions during geomagnetic storms. In this paper, DNB observations of auroral activities are analyzed during a long period (> 20 hours) of geomagnetic storm event occurred on Apr. 29-30, 2014. The storm event has the Bz component of interplanetary magnetic field (IMF) pointing southward for more than 20 hours. During this event, the geomagnetic storm index Dst reached -67 nT and the geomagnetic auroral electrojet (AE) index increased and reached as high as 1200 nT with large amplitude fluctuations. The event occurred during new moon period and DNB observation has minimum moon light contamination. During this event, auroras are observed by DNB for each orbital pass on the night side (~local time 1:30am) in the southern hemisphere. DNB radiance data are processed to identify regions of aurora during each orbital pass. The evolution of aurora is characterized with time series of the poleward and equatorward boundary of aurora, area, peak radiance and total light emission of the aurora in DNB observation. These characteristic parameters are correlated with solar wind and geomagnetic index parameters. It is found that the evolution of total area-integrated radiance of auroral region over the southern hemisphere correlated well with the ground geomagnetic AE index with correlation coefficient = 0.71. DNB observations of aurora help understand the relations among solar wind variation, auroral activities and geomagnetic responses.

Proceedings Article | 12 October 2015 Paper

The GOES-R Advanced Baseline Imager: detector spectral response effects on thermal emissive band calibration

Aaron Pearlman, Francis Padula, Changyong Cao, Xiangqian Wu

Proceedings Volume 9639, 963917 (2015) https://doi.org/10.1117/12.2195195

KEYWORDS: Sensors, Black bodies, Calibration, Imaging systems, Thermal effects, Satellites, Signal detection, Image sensors, Earth's atmosphere, Satellite imaging

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The Advanced Baseline Imager (ABI) will be aboard the National Oceanic and Atmospheric Administration’s Geostationary Operational Environmental Satellite R-Series (GOES-R) to supply data needed for operational weather forecasts and long-term climate variability studies, which depend on high quality data. Unlike the heritage operational GOES systems that have two or four detectors per band, ABI has hundreds of detectors per channel requiring calibration coefficients for each one. This increase in number of detectors poses new challenges for next generation sensors as each detector has a unique spectral response function (SRF) even though only one averaged SRF per band is used operationally to calibrate each detector. This simplified processing increases computational efficiency. Using measured system-level SRF data from pre-launch testing, we have the opportunity to characterize the calibration impact using measured SRFs, both per detector and as an average of detector-level SRFs similar to the operational version. We calculated the spectral response impacts for the thermal emissive bands (TEB) theoretically, by simulating the ABI response viewing an ideal blackbody and practically, with the measured ABI response to an external reference blackbody from the pre-launch TEB calibration test. The impacts from the practical case match the theoretical results using an ideal blackbody. The observed brightness temperature trends show structure across the array with magnitudes as large as 0.1 K for and 12 (9.61 µm), and 0.25 K for band 14 (11.2 µm) for a 300 K blackbody. The trends in the raw ABI signal viewing the blackbody support the spectral response measurements results, since they show similar trends in bands 12 (9.61µm), and 14 (11.2 µm), meaning that the spectral effects dominate the response differences between detectors for these bands. We further validated these effects using the radiometric bias calculated between calibrations using the external blackbody and another blackbody, the ABI on-board calibrator. Using the detector-level SRFs reduces the structure across the arrays but leaves some residual bias. Further understanding of this bias could lead to refinements of the blackbody thermal model. This work shows the calibration impacts of using an average SRF across many detectors instead of accounting for each detector SRF independently in the TEB calibration. Note that these impacts neglect effects from the spectral sampling of Earth scene radiances that include atmospheric effects, which may further contribute to artifacts post-launch and cannot be mitigated by processing with detector-level SRFs. This study enhances the ability to diagnose anomalies on-orbit and reduce calibration uncertainty for improved system performance.