The Contribution of ROSAS Automated Photometric Station to Vicarious Calibration of PLEIADES PHR1A Satellite

ROSAS (Robotic Station for Atmosphere and Surface) has been used since 1997 in the site of LaCrau, in South East of France, to perform ground truth campaigns. The principle of these campaigns is to characterize the optical properties of the atmosphere through measurements of the solar extinction, sky radiance and upwelling radiance of the ground, simultaneously to the satellite overpass. The data are automatically processed, in order to calibrate the photometer and estimate the bidirectional reflectance distribution function of the site. This allows to simulate the top of atmosphere radiance in the geometric conditions of any satellite over-passing the site. The instrument, calibration principle and measurement protocol will be presented first. Then, after a description of the operational software used to collect and process the data, the first PLEIADES calibration results will be discussed, and compared to the results of other calibration methods. Taking advantage of PLEIADES tremendous agility, a single over-pass can contain up to 24 different satellite viewing angles over the calibration site, allowing to cross-validate the estimation of the bidirectional reflectance distribution of the site, thus improving the computation of the TOA radiance, and the accuracy of the calibration results

New RadCalNet Instrumented Site at Gobabeb, Namibia: Field Campaign Conclusions and First Absolute Calibration Results

A new permanently instrumented radiometric calibration site for high/medium resolution imaging satellite sensors in the visible/near-IR has been set up in Namibia, near the Gobabeb Research and Training Centre on the edge of the Namib Desert. This site is the European contribution to the Committee on Earth Observation Satellites (CEOS) initiative RadCalNet (Radiometric Calibration Network). The Gobabeb area has been selected based on the analysis of different datasets to estimate surface spatial homogeneity, cloud coverage, temporal variability, atmospheric turbidity and flatness. A field campaign took place in November 2015 in order to find the precise location of the future permanent instrumentation in the area identified from satellite data (Modis, Landsat8, Sentinel2, Pleiades). This location is the one with the best spatial homogeneity at different scales: instrument field-of-view (tens of centimeters), extent of the instrument-monitored area (tens of meters) and satellite sensor resolution (tens to hundreds of meters). The field campaign also focused on the characterization of the surface reflectance, the surface hemispherical directional reflectance factor and the atmospheric turbidity. Following this campaign, the permanent instrumentation (CIMEL photometer) has been installed in May/June 2016. The data has been processed by the ROSAS processing software at CNES in order to obtain first results of surface reflectance and to perform the vicarious absolute calibration of optical sensors (Sentinel2, Sentinel3 etc.). The presentation will focus on the field campaign conclusions and the analysis of the data produced by this new calibration station

New RadCalNet Instrumented Site at Gobabeb, Namibia: Installation Field Campaign and First Absolute Calibration Results

A new permanently instrumented radiometric calibration site for high/medium resolution imaging satellite sensors in the visible/near-IR has been set up in Namibia, near the Gobabeb Research and Training Centre on the edge of the Namib Desert. This site is the European contribution to the Committee on Earth Observation Satellites (CEOS) initiative RadCalNet (Radiometric Calibration Network). The Gobabeb area has been selected based on the analysis of different datasets to estimate surface spatial homogeneity, cloud coverage, temporal variability, atmospheric turbidity and flatness. A field campaign took place in November 2015 in order to find the precise location of the future permanent instrumentation in the area identified from satellite data (Modis, Landsat8, Sentinel2, Pleiades). This location is the one with the best spatial homogeneity at different scales: instrument field-of-view (tens of centimeters), extent of the instrument-monitored area (tens of meters) and satellite sensor resolution (tens to hundreds of meters). The field campaign also focused on the characterization of the surface reflectance, the surface hemispherical directional reflectance factor and the atmospheric turbidity. Following this campaign, the permanent instrumentation (CIMEL photometer) has been installed in June 2017 and has the ability to measure atmosphere (aerosol optical thickness etc.) and surface conditions (reflectance). The data has been processed by the ROSAS processing software at CNES in order to obtain first results of surface reflectance and to perform the vicarious absolute calibration of optical sensors (Sentinel2A and Sentinel2B, Landsat8 etc.) The presentation will focus on the installation field campaign and the analysis of the data produced by this new calibration station

SPOT4 HRVIR first in-flight image quality results

Communication to : EUROPTO 98, Barcelona (Spain), September 21-25, 1998SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1998 n.228 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Radiometric Calibration Network for Vicarious Calibration of Earth Observing Imagers in the Reflected Solar

A challenge for the scientific community in respect to the ever-increasing number of Earth observing satellite sensors is to ensure that the absolute radiometric calibration of the sensors is harmonized to the same SI-traceable scale. Assessing the post-launch radiometric calibration is the responsibility of each sensor team and typically involves simulating the top-of-atmosphere signal from in-situ and atmospheric measurements. As this is done on an individual sensor-by-sensor basis often using a single ground site, radiometric biases can exist between sensors. In an effort to minimize these biases, the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV) Infrared Visible Optical Sensors (IVOS) is currently working to develop the prototype radiometric calibration network, RadCalNet. This network will standardize methodology and processing streams for participating ground sites. The current RadCalNet working group consists of members from the National Aeronautics and Space Administration (NASA, USA), the Centre National d’Etudes Spatiales (CNES, France), the European Space Agency (ESA), the National Physical Laboratory (NPL, UK), the University of Arizona (USA), and the Academy of Opto Electronics (AOE, China). Four radiometric calibration test sites in the USA, France, China, and Namibia are being used as test cases for the collection of surface reflectance and atmospheric data, which are then converted to top-of-atmosphere (TOA) reflectance for comparison with a limited number of satellite sensors. The goal of the RadCalNet working group is to provide via a public website site the hyper-spectral (in the range 400 nm to 1000 nm and at specific sites up to 2500 nm) top-of-atmosphere reflectance at 30-minute intervals for a nadir viewing sensor for the 4 sites. RadCalNet recently completed its Beta Testing Phase and examples from that testing phase as well as a description of the method for providing uncertainties and ensuring SI-traceability are presented

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

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.European Space Agency Technology and Research Programme [4000110704]; European Space Agency Earthnet Programme [CCN5 4000110704]; Metrology for Earth Observation and Climate project (MetEOC-2) within the EMRP programme [ENV55 532]; EURAMET; European Union's FP7 programme; European Union's H2020 programme; European Space Agency Technology and Research Programme through the ACTION project; UK Government's Department for Business, Energy and Industrial Strategy (BEIS) through the UK's National Measurement System programmes; Bureau of International Co-operation Chinese Academy of SciencesChinese Academy of Sciences [181811KYSB20160040]; NASANational Aeronautics & Space Administration (NASA) [NNX14AE20G, NNX15AM86G, NNX16AL25G]; USGSUnited States Geological Survey [G14AC00371]; MetEOC-3 project under the EMPIR programme [16ENV03]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]