Dr. Xuewen Zhang Profile

Dr. Xuewen Zhang

at CRESDA

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Publications (4)

SPIE Journal Paper | 8 January 2018

Cross calibration of GF-1 satellite wide field of view sensor with Landsat 8 OLI and HJ-1A HSI

Li Liu, Hailiang Gao, Zhiqiang Pan, Xingfa Gu, Qijin Han, Xuewen Zhang

JARS, Vol. 12, Issue 01, 016009, (January 2018) https://doi.org/10.1117/12.10.1117/1.JRS.12.016009

KEYWORDS: Calibration, Reflectivity, Sensors, Satellites, Earth observing sensors, Landsat, Near infrared, Image sensors, Atmospheric modeling, Satellite imaging

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Proceedings Article | 18 November 2014 Paper

Using the Dunhuang test site to monitor the radiometric stability of the ZY-3 multispectral sensor

Xuewen Zhang, Qijin Han, Li Liu

Proceedings Volume 9298, 92980H (2014) https://doi.org/10.1117/12.2070938

KEYWORDS: Calibration, Reflectivity, Atmospheric optics, Satellites, Atmospheric particles, Sensors, Radio optics, Aerosols, Atmospheric modeling, Reliability

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The ZY-3 satellite plays an important role in agriculture, forestry, water conservancy, ecological environment, and so on since its successfully running. In order to achieve continuity, stability and reliability of the remote sensing data, and improve quantitative application level of the ZY-3 satellite data, an accurate sensor radiometric calibration is essential. Because ZY-3 satellite doesn’t have onboard calibration system, in-fight filed absolute radiometric calibration as a means to effective monitor the radiometric stability.This paper uses multi-day, multi-field at the Dunhuang test site to calibrate the ZY-3 multispectral sensor. The experiment obtained a synchronization measurement data on the August 18, 23 and 28, respectively. The two of ground surface were selected for measuring reflectance, which middling reflectance field (20%) and high reflectance field (40%). At the time of the ZY-3 overpass on the site, synchronous measure surface reflectance of ground targets, atmospheric optical characteristics parameters, such as atmospheric aerosol optical depth, atmospheric columnar water vapor content. Then use the radiative transfer model to estimate the top of atmosphere (TOA) radiance for MSS band. Radiometric calibration coefficient of MSS band was estimated by comparing the TOA radiance with average digital number of the MSS image. Based on multi-day, multi-field, and the real-time measurement at the Dunhuang site, radiometric calibration for ZY-3 MSS was successfully performed using reflectance-based method and calibration coefficients for MSS bands were obtained as well. According to contrast between in-fight calibration and the prelaunch, it was shown that the response of MSS changed at some extent after launch, especially band 1 and band 4. As a result, it was quite essential to update calibration coefficient timely and periodically in order to monitor the change of ZY-3 MSS better and to improve the quantitative application of MSS data as well.

Proceedings Article | 18 November 2014 Paper

Lifetime radiometric calibration of HJ-1A/B CCD sensor using Dunhuang Gobi site

Qijin Han, Xuewen Zhang, Li Liu, Aichun Wang

Proceedings Volume 9299, 92990B (2014) https://doi.org/10.1117/12.2070348

KEYWORDS: Calibration, Charge-coupled devices, Sensors, CCD image sensors, Satellites, Reflectivity, Remote sensing, Environmental sensing, Sensor calibration, Environmental monitoring

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Proceedings Article | 18 November 2014 Paper

Multitemporal cross-calibration of GF-1 WFV and Terra MODIS reflective solar bands

Li Liu, Tingting Shi, Qijin Han, Xuewen Zhang

Proceedings Volume 9298, 92980G (2014) https://doi.org/10.1117/12.2070922

KEYWORDS: MODIS, Reflectivity, Sensors, Calibration, Satellites, Spatial resolution, Bidirectional reflectance transmission function, Oxygen, Absorption, Atmospheric particles

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The Gao Fen-1(GF-1) satellite with WFV sensors onboard was launched on April 26, 2013, as part of Gao Fen earth observing system. The Terra Moderate Resolution Imaging Spectroradiometer (MODIS) has been operational for more than a decade. With its high accuracy onboard calibration system, the data from MODIS has become a critical component of numerous applications. Cross-calibration between the sensors is critical to bring the measurements from different sensors to a common radiometric scale. Because of the differences in the spectral reflectance function (SRF), the measured physical quantities can be significantly different while observing the same target. This paper focuses on evaluation the radiometric calibration agreement between GF-1/WFV and Terra/MODIS using the near-simultaneous and cloud-free image pairs over Dun huang pseudo-invariant calibration site in the visible and near-infrared spectral range. The SRF differences of the analogous WFV and MODIS spectral bands provide the opportunity to explore, understand, quantify, and compensate for the measurement differences between these two sensors. Assuming that the ground target is spectrally and temporally stable, a typical reflectance spectrum over the Dun huang site obtained by in-situ measurements was used to compute spectral band adjustment factors (SBAF) for the cross-calibration. No BRDF correction was applied to reduce the seasonal oscillations since the analysis were restricted to only near-nadir images. The cross-calibration was initially performed by comparing the top-of-atmosphere (TOA) reflectance between the two sensors. WFV band 4 has the presence of the water vapor and oxygen absorption features which is absent from the corresponding MODIS band 2 which made the WFV measured TOA reflectance lower than the MODIS’s. Overall, the average percent differences were consistent to within 7%. The long-term cross-calibration results reflected that WFV sensor is stable since launch. Although the application of the techniques presented in this paper was focused on comparing near- nadir observations from WFV and MODIS reflective solar bands, it can be easily extended and applied to evaluate the differences between any other similar sensors.

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