A5023329372- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- Satellite Image Processing and Photogrammetry
- Marine and coastal ecosystems
- Remote Sensing in Agriculture
- Spacecraft Design and Technology
- Infrared Target Detection Methodologies
- Atmospheric aerosols and clouds
- Water Quality Monitoring Technologies
- Water Quality Monitoring and Analysis
- Remote-Sensing Image Classification
- Atmospheric and Environmental Gas Dynamics
- Spectroscopy and Chemometric Analyses
- Color perception and design
- Urban Heat Island Mitigation
- Planetary Science and Exploration
- Geophysical Methods and Applications
- Geochemistry and Geologic Mapping
- Remote Sensing and LiDAR Applications
- Aesthetic Perception and Analysis
- Scientific Measurement and Uncertainty Evaluation
- Oceanographic and Atmospheric Processes
- Multisensory perception and integration
- Advanced Measurement and Metrology Techniques
- Optical measurement and interference techniques
National Physical Laboratory
2014-2025
University of Surrey
2016
Vicarious calibration approaches using in situ measurements saw first use the early 1980s and have since improved to keep pace with evolution of radiometric requirements sensors that are being calibrated. The advantage for vicarious is they can be carried out traceable quantifiable accuracy, making them ideal interconsistency studies on-orbit sensors. recent development automated sites collect data has led an increase available number datasets sensor calibration. current work describes...
The LANDHYPERNET and WATERHYPERNET networks (which together make up the HYPERNETS network) consist of a set autonomous hyperspectral spectroradiometers (HYPSTAR ® ) acquiring fiducial reference measurements surface reflectance at various sites covering wide range types (both land water) for use in satellite Earth observation validation remote sensing applications. This paper describes processing algorithm HYPSTAR data products. hypernets_processor is Python software package to process...
Satellites are now routinely used for measuring water and land surface reflectance hence environmentally relevant parameters such as aquatic chlorophyll a concentration terrestrial vegetation indices. For each satellite mission, radiometric validation is needed at bottom of atmosphere all spectral bands covering typical conditions where the data will be used. Existing networks AERONET-OC RadCalNet provide vital information validation, but (AERONET-OC) do not cover or (RadCalNet) types...
Field spectroradiometers are often comprised of several spectral detectors to sample the full range reflected solar irradiance. An example such an instrument is Analytical Spectral Devices (ASD) full-range spectroradiometer, featuring three capture spectra between 350 and 2500 nm. The resulting exhibit radiometric steps at joints these detectors. This study investigates influence external temperature humidity on magnitude by experiments based a climate chamber. Relative errors detector...
This paper describes a prototype network of automated in situ measurements hyperspectral water reflectance suitable for satellite validation and quality monitoring. Radiometric satellite-derived is essential to ensure that only reliable data, e.g., estimating parameters such as chlorophyll concentration, reach end-users. Analysis the differences between measurements, particularly unmasked outliers, can provide recommendations on where data processing algorithms need be improved. In massively...
Verifying and validating waterleaving radiance measurements from space for an accurate derivation of Ocean/Water Colour biogeophysical products is based on concurrent high-quality fiducial reference (FRM) carried out the ground or water body. The FRM principles established by Committee Earth Observation Satellites (CEOS) recommend that in situ Ocean radiometers (OCR) have a documented history SI traceable calibrations including uncertainty budgets. Furthermore, there can be significant...
Abstract System Vicarious Calibration (SVC) enhances the accuracy of satellite ocean color radiometric data products by removing bias due to intrinsic inaccuracies affecting both responsivity space sensor and correction for atmospheric sea surface contributions measured signal. Various SVC procedures have been implemented applied regional studies, specific mission goals, most challenging quantification global, long-term, climate-driven changes that require accurate consistent across multiple...
A radiometric field intercomparison was conducted at the Acqua Alta Oceanographic Tower (AAOT) in Adriatic Sea from 14 to 21 July 2022 assess differences accuracy of above-water radiometer systems (Sea-Bird HyperSAS, pySAS, TriOS-RAMSES) processed using an open-source community processor (HyperCP). Class-based and sensor-specific characteristics radiometers were used determine quantities Ed(λ), Lsky(λ), Lt(λ) Rrs(λ), their associated uncertainties. Using characteristics, among 2% for 2.5%...
 Pan-European Network of Green Deal Agriculture and Forestry Earth Observation Science (PANGEOS) funded by the European Cooperation in Technology (COST) organisation brings together researchers to share their expertise bring up a new generation scientists. In October 2024 PANGEOS conducted an intensive 5-day summer school where more than 20 participants learnt how propagate uncertainty spectral measurements higher-level products. The training material form Python Jupyter notebooks...
Earth observation data can help us understand and address some of the grand challenges threats facing today as a species planet, for example climate change its impacts sustainable use Earth’s resources. However, in order to have confidence earth data, measurements made at surface Earth, with intention providing verification or validation satellite-mounted sensor measurements, should be trustworthy least same high quality those taken satellite sensors themselves. Metrology tells that...
This paper demonstrates the use of a novel, autonomous hyperspectral surface reflectance data collected at Wytham Woods, United Kingdom (WWUK) as part LANDHYPERNET network for validation multispectral from Sentinel-2, Landsat 8 and 9. The deployment HYPSTAR instrument site corresponding quality control products is described. In addition, methodology based upon metrological principles outlined showing propagation uncertainties satellite to enable conformity testing using mission requirements....
The bandpass of spectrometers can cause appreciable errors when making radiometric measurements. This paper describes a practical method for correcting set equispaced measured values provided by spectrometer with finite bandwidth, an arbitrary function and at wavelength step. reviews the limits approach real spectra in presence measurement noise suggests ways reducing effect noise.
A new goniometer for in situ spectro-directional measurements of the reflection and transmission properties individual leaves is presented. One diffuse five directional illumination angles can be chosen. multichannel spectrometer allows simultaneous detection scattered light at 80 viewing spectral range from 400 nm to 1000 nm.
A new spectrally tunable source for calibration of radiometric detectors in radiance, irradiance, or power mode has been developed and characterized. It is termed the absolute irradiance radiance (STAIRS). consists a supercontinuum laser, wavelength bandpass filter, stabilization feedback control scheme, output coupling optics. advantages relative portability collimated beam (low étendue), an alternative to conventional sources such as tungsten lamps, blackbodies, lasers. The laser...
We describe a method to evaluate an uncertainly budget for the in situ Ocean Colour Radiometric measurements. A Monte Carlo approach is chosen propagate measurement uncertainty inputs through measurements model. The model designed address instrument characteristics and associated with them. present results particular example when radiometers were fully characterised then use same data show case such characterisation missing. This, depending on wavelength, can increase value significantly;...
Abstract. Absolute calibration of Earth observation (EO) sensors is key to ensuring long-term stability and interoperability, it essential for global climate records forecasts. The Moon provides a photometrically stable source within the range Earth's radiometric levels free from atmospheric interference. However, use this ideal source, one must model variation in its disc-integrated irradiance resulting changes Sun–Earth–Moon geometries. Lunar Irradiance Model European Space Agency (LIME)...
The HYPERNETS project developed a new hyperspectral radiometer (HYPSTAR ® ) integrated in automated networks of water (WATERHYPERNET) and land (LANDHYPERNET) bidirectional reflectance measurements for satellite validation. In this paper, the feasibility using LANDHYPERNET surface data vicarious calibration multispectral (Sentinel-2 Landsat 8/9) (PRISMA) satellites is studied. pipeline to process bottom atmosphere (BOA) band-integrated top (TOA) reflectances compare them observations...
A new permanently instrumented radiometric calibration site for high/medium resolution imaging satellite sensors is currently under development, focussing on the visible and near infra-red parts of spectrum. The will become a European contribution to Committee Earth Observation Satellites (CEOS) initiative RadCalNet (Radiometric Calibration Network). This paper describes characterisation that was carried out, both define exact location permanent monitoring instrumentation, provide an initial...
Abstract A new framework that enables evaluation of the in situ ocean color radiometry measurement uncertainty is presented. The study was conducted on multispectral data from a permanent mooring deployed clear open water. evaluated for each component equation and processing step leads to deriving remote sensing reflectance. Monte Carlo method selected handle complexity such as correlation nonlinearity an efficient manner. results are presented prescreened dataset suitable system vicarious...
This paper describes spectral stray light measurements of diode array spectrometers and, in particular, the dependence and bandpass properties on illumination beam geometry. The effects underfilling overfilling nominal field view instrument are presented. Our showed that line spread function a commercially available miniature spectrometer module having fiber optic entrance with 0.22 numerical aperture can depend cone apex angle up to 40°, which is well above 25° acceptance fiber. width...
An international round-robin experiment has been conducted to test procedures and methods for the measurement of angle-resolved light scattering. ASTM E2387-05 used as main guide, while experience gained should also contribute new ISO standard scattering currently under development (ISO/WD 19986:2016). Seven laboratories from Europe United States measured Al/SiO2-coated substrates, transparent volume diffusors, quasi-volume white calibration standards, grating samples at laser wavelengths in...
The European Copernicus programme ensures long-term delivery of high-quality, global satellite ocean colour radiometry (OCR) observations from its Sentinel-3 (S3) series carrying the and land instrument (OLCI). In particular, S3/OLCI provides marine water leaving reflectance derived products to environment monitoring service, CMEMS, for which data quality is paramount importance. This why OCR system vicarious calibration (OC-SVC), allows uncertainties these stay within required...
Abstract. Absolute calibration of Earth observation sensors is key to ensuring long term stability and interoperability, essential for global climate records forecasts. The Moon provides a photometrically stable source, within the range radiometric levels free from atmospheric interference. However, use this ideal source one must model variation its disk integrated irradiance resulting changes in Sun-Earth-Moon geometries. LIME, Lunar Irradiance Model European Space Agency, new lunar...