Evaluation of Sen2cor Surface Reflectance Products Over Land Surface With Reference Measurements on Ground

Pflug, Bringfried; Louis, Jereome; Reyes, R. de los; Pflug, Katharina; Müeller-Wilm, Uwe; Quang, Carine; Iannone, Rosario; Reinartz, Peter

doi:10.1109/igarss46834.2022.9883369

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…In this paper, we report on the calibration of an HR-1024i spectroradiometer from the Spectra Vista Corporation (SVC) and its application in radiance transfer measurements. This spectroradiometer model provides reflectance spectra for validating airborne and satellite hyperspectral data [ 5 , 6 ] and the non-destructive measurements of plant traits [ 7 , 8 , 9 , 10 ]. On the other hand, an HR-1024i spectroradiometer is applied as a radiance transfer spectroradiometer in the Calibration Home Base (CHB) of the Remote Sensing Technology Institute (IMF) at the German Aerospace Center (DLR) [ 11 ] for the radiometric calibration of several hyperspectral imaging systems such as the Airborne Prism Experiment (APEX) [ 12 ], the Munich Aerosol Cloud Scanner (specMACS) [ 13 ], and the Environmental Mapping and Analysis Program (EnMAP) [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Spectroradiometer Calibration for Radiance Transfer Measurements

Rammeloo

Baumgartner

2023

Sensors

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Optical remote sensing and Earth observation instruments rely on precise radiometric calibrations which are generally provided by the broadband emission from large-aperture integrating spheres. The link between the integrating sphere radiance and an SI-traceable radiance standard is made by spectroradiometer measurements. In this work, the calibration efforts of a Spectra Vista Corporation (SVC) HR-1024i spectroradiometer are presented to study how these enable radiance transfer measurements at the Calibration Home Base (CHB) for imaging spectrometers at the Remote Sensing Technology Institute (IMF) of the German Aerospace Center (DLR). The spectral and radiometric response calibrations of an SVC HR-1024i spectroradiometer are reported, as well as the measurements of non-linearity and its sensitivity to temperature changes and polarized light. This achieves radiance transfer measurements with the calibrated spectroradiometer with relative expanded uncertainties between 1% and 3% (k=2) over the wavelength range of 380 nm to 2500 nm, which are limited by the uncertainties of the applied radiance standard.

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Section: Introductionmentioning

confidence: 99%

Spectroradiometer Calibration for Radiance Transfer Measurements

Rammeloo

Baumgartner

2023

Sensors

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“…This means that in situ measurements need to ensure that environmental conditions are consistent with the airborne or spaceborne data, especially the angle conditions, field of view, etc. [11,12]. However, practice has proven that synchronous observation is difficult to realize.…”

Section: Introductionmentioning

confidence: 99%

The Impact and Correction of Sensitive Environmental Factors on Spectral Reflectance Measured In Situ

Zhao,

Wang,

Jia

et al. 2023

Remote Sensing

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The spectral reflectance measured in situ is often regarded as the “truth” of objects, which plays an important role in Earth observation applications. However, in situ measurements are influenced by several factors such as atmospheric conditions, illumination and view geometry (I&VG), cloud coverage, and adjacency effects. In order to avoid the influence of these factors, in situ measurements are usually carried out under sunny days and close to noon. However, the impact of I&VG is still present in most cases. At present, people still know little about the influence mechanism of I&VG. Moreover, correcting the impact of I&VG is also a problem that needs to be urgently solved in reflectance spectroscopy. In this work, experiments are carried out using the multi-directional hyperspectral remote sensing simulation facility (MHSRS2F), which allows adjustment and control of the I&VG parameters. This paper proposes an uncertainty evaluation model for I&VG and quantifies the uncertainty caused by different I&VG parameters. Then, the sensitivity of reflectance to I&VG at different wavelengths is explored based on uncertainty models. Finally, a correction model for reflectance under different I&VG conditions is proposed. The results reveal that the uncertainty and sensitivity caused by observation height are relatively high, regardless of the surface heterogeneity. It directly affects the size of the field of view and the physicochemical characteristics of the object. For objects that approximate the Lambertian surface, more attention should be paid to the selection and variation of solar and view zenith angles and view azimuth angles. For objects with surface heterogeneity, the selection and variation of solar azimuth angle, view azimuth angle, and solar zenith angle are more crucial. The correction model proposed in this paper has a 41.25% correction effect on different view zenith angles, but the correction effect on other environmental factors is not significant.

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Utilising LANDHYPERNET data products over a deciduous broadleaf forest to validate Sentinel-2 and Landsat surface reflectance products

Morris,

Sinclair,

De Vis

et al. 2024

Front. Remote Sens.

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This paper demonstrates the use of a novel, autonomous hyperspectral surface reflectance data collected at Wytham Woods, United Kingdom (WWUK) as part of the LANDHYPERNET network for the validation of multispectral data from Sentinel-2, Landsat 8 and Landsat 9. The deployment of the HYPSTAR instrument at the site and the corresponding quality control of the data products is described. In addition, a methodology based upon metrological principles is outlined showing the propagation of uncertainties from the LANDHYPERNET and satellite data products to enable conformity testing of the satellite products using the satellite mission requirements. A total of 9 matchups are found for satellite validation at the site, where there is a cloud-free satellite scene and a corresponding LANDHYPERNET sequence, which has passed all quality checks, within two hours of the overpass. An analysis of the impact of the spatial variability of the site is presented and can account for up to 40% of the uncertainty associated with the in-situ surface reflectance data. There is no systematic bias in the Bottom-Of-Atmosphere reflectance data obtained from the LANDHYPERNET data in comparison to the satellite data. In the best case, differences of less than 2% are found for certain spectral bands. However, in the worst cases, relatively large differences are found which exceed 100%, this is affected by the relatively low reflectance values found in the visible bands. These differences could be caused by the spatial and temporal mismatch between the in-situ and satellite measurement, or due to shadowing caused by the flux tower. Further data quality control and assurance is needed to best choose data sets suitable for satellite validation. Incorporating a Bidirectional Reflectance Distribution Function model into the processing chain for the forest canopy is recommended. Overall, although there are areas to further characterise, the site provides a useful benchmark for which to develop techniques for validation of satellite surface reflectance products over a challenging environment.

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Evaluation of Sen2cor Surface Reflectance Products Over Land Surface With Reference Measurements on Ground

Cited by 3 publications

References 5 publications

Spectroradiometer Calibration for Radiance Transfer Measurements

Spectroradiometer Calibration for Radiance Transfer Measurements

The Impact and Correction of Sensitive Environmental Factors on Spectral Reflectance Measured In Situ

Utilising LANDHYPERNET data products over a deciduous broadleaf forest to validate Sentinel-2 and Landsat surface reflectance products

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