New radiometric calibration site located at Gobabeb, Namib desert

Białek, Agnieszka; Greenwell, Claire; Lamare, Maxim; Meygret, Aimé; Marcq, Sébastien; Lachérade, Sophie; Woolliams, Emma; Berthelot, Béatrice; Bouvet, Marc; King, Martin D.; Underwood, Craig; Fox, Nigel

doi:10.1109/igarss.2016.7730592

Cited by 13 publications

(10 citation statements)

References 2 publications

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“…The Baotou site was not included in this study, due to the small size of the representative area compared to the sensors' spatial resolution. GONA is situated in the gravel plains at the edge of the Namib Desert and was selected because of its high spatial homogeneity, low cloud coverage, relatively high surface reflectance stability, and stable atmospheric conditions [18]. LCFR is located in southeastern France, and its surface is uniformly covered by pebbles and dry grass-like vegetation.…”

Section: Radcalnetmentioning

confidence: 99%

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Radiometric Top-of-Atmosphere Reflectance Consistency Assessment for Landsat 8/OLI, Sentinel-2/MSI, PROBA-V, and DEIMOS-1 over Libya-4 and RadCalNet Calibration Sites

Sterckx

Wolters

2019

Remote Sensing

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There is a clear trend toward the use of higher spatial resolution satellite sensors. Due to the low revisit time of these sensors and frequent cloud coverage, many applications require data from different sensors to be combined in order to have more frequent observations. This raises concerns regarding data interoperability and consistency. The initial pre-requisite is that there are no radiometric differences in top-of-atmosphere (TOA) observations. This paper aims to quantitatively assess differences in the TOA signal provided by PROBA-V, Sentinel-2A and Sentinel-2B, Landsat-8, and Deimos-1 by using observations over both the Libya-4 desert calibration site and the RadCalNet sites. The results obtained over the Libya-4 site indicate that for all sensors investigated, the inter-sensor deviations are negligible, i.e., within ±2% for comparable spectral bands, with the exception of the Deimos-1 Green band. Clear BRDF (bi-directional reflectance distribution function) effects were observed over the RadCalNet sites, thereby preventing consistent conclusions on inter-sensor deviations from being made. In order to fully explore the potential of the RadCalNet sites, it is recommended that BRDF characterizations be additionally incorporated into the RadCalNet simulations and made publicly available through the distribution portal.

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Section: Radcalnetmentioning

confidence: 99%

“…RVUS is located in Nevada (USA) in a dry lakebed or playa. Changes in the surface characteristics are generally due to rain and snow [18,19].…”

Section: Radcalnetmentioning

confidence: 99%

Radiometric Top-of-Atmosphere Reflectance Consistency Assessment for Landsat 8/OLI, Sentinel-2/MSI, PROBA-V, and DEIMOS-1 over Libya-4 and RadCalNet Calibration Sites

Sterckx

Wolters

2019

Remote Sensing

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“…The list of sand samples that were characterized in this study, is presented in Table 2. These samples originate from other areas of potential interest for Calibration/Validation (Cal/Val) activities: five samples from Namibia [9,10] and among them one coming from the RADiometric CALibration NETwork of automated instruments (RadCalNet) [11], six samples from the Pinnacles desert in Australia [12], two samples of bays in Australia which are used as Standard for laboratory measurements [13], two samples from Libya, one sample from Morocco, one sample from Niger, and two samples from well-known Cal/Val sites from United States of America [14,15].…”

Section: Methodsmentioning

confidence: 99%

Contribution to Sandy Site Characterization: Spectro-Directional Signature, Grain Size Distribution and Mineralogy Extracted from Sand Samples

et al. 2019

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The characterization of sands detailed in this paper has been performed in order to support the in-flight radiometric performance assessment of space-borne optical sensors over the so-called Pseudo-Invariant Calibration Sites (PICS). Although the physical properties of PICS surface are fairly stable in time, the signal measured from space varies with the illumination and the viewing geometries. Thus, there is a need to characterize the spectro-directional properties of PICS. This could be done on a broad scale, thanks to multi-spectral multi-directional space-borne sensors such as the POLDER instrument (with old data). However, interpolating or extrapolating the spectro-directional reflectance measured from space to spectral bands of another sensor is not straightforward. The hyperspectral characterization of sand samples collected within or nearby PICS could contribute to a solution. In this context, a set of 31 sand samples was compiled. The BiConical Reflectance Factor (BCRF), linked to Bidirectional Reflectance Distribution Function (BRDF), was measured between 0.4 and 2.5 µm, over a half hemisphere when the amount of sand in the sample was large enough and for only a single fixed angular configuration for small samples. These optical measurements were complemented by grain size distribution measurements and mineralogical analysis and compiled together with previously published measurements in the so-called PICSAND database, freely available online.

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“…The fourth site is in Gobabeb, Namibia. This was set up during the RadCalNet prototype phase and has been providing data from July 2017 [35,36]. It is operated jointly by European Space Agency (ESA) (subcontracting to the National Physical Laboratory of Unites Kingdom (NPL)) and CNES and has the same type of instrument and operational protocol as the La Crau ROSAS system, and the data are analyzed using the same analysis software at CNES.…”

Section: Radcalnet Instrumented Sitesmentioning

confidence: 99%

RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range

et al. 2019

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Vicarious calibration approaches using in situ measurements saw first use in the early 1980s and have since improved to keep pace with the evolution of the radiometric requirements of the sensors that are being calibrated. The advantage of in situ measurements for vicarious calibration is that they can be carried out with traceable and quantifiable accuracy, making them ideal for interconsistency studies of on-orbit sensors. The recent development of automated sites to collect the in situ data has led to an increase in the available number of datasets for sensor calibration. The current work describes the Radiometric Calibration Network (RadCalNet) that is an effort to provide automated surface and atmosphere in situ data as part of a network including multiple sites for the purpose of optical imager radiometric calibration in the visible to shortwave infrared spectral range. The key goals of RadCalNet are to standardize protocols for collecting data, process to top-of-atmosphere reflectance, and provide uncertainty budgets for automated sites traceable to the international system of units. RadCalNet is the result of efforts by the RadCalNet Working Group under the umbrella of the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV) and the Infrared Visible Optical Sensors (IVOS). Four radiometric calibration instrumented sites located in the USA, France, China, and Namibia are presented here that were used as initial sites for prototyping and demonstrating RadCalNet. All four sites rely on collection of data for assessing the surface reflectance as well as atmospheric data over that site. The data are converted to top-of-atmosphere reflectance within RadCalNet and provided through a web portal to allow users to either radiometrically calibrate or verify the calibration of their sensors of interest. Top-of-atmosphere reflectance data with associated uncertainties are available at 10 nm intervals over the 400 nm to 1000 nm spectral range at 30 min intervals for a nadir-viewing geometry. An example is shown demonstrating how top-of-atmosphere data from RadCalNet can be used to determine the interconsistency between two sensors.

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New radiometric calibration site located at Gobabeb, Namib desert

Cited by 13 publications

References 2 publications

Radiometric Top-of-Atmosphere Reflectance Consistency Assessment for Landsat 8/OLI, Sentinel-2/MSI, PROBA-V, and DEIMOS-1 over Libya-4 and RadCalNet Calibration Sites

Radiometric Top-of-Atmosphere Reflectance Consistency Assessment for Landsat 8/OLI, Sentinel-2/MSI, PROBA-V, and DEIMOS-1 over Libya-4 and RadCalNet Calibration Sites

Contribution to Sandy Site Characterization: Spectro-Directional Signature, Grain Size Distribution and Mineralogy Extracted from Sand Samples

RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range

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