Periodic Reporting for period 3 - HYPERNETS (A new hyperspectral radiometer integrated in automated networks of water and land bidirectional reflectance measurements for satellite validation)
Período documentado: 2021-01-01 hasta 2023-04-30
Networking of automated instruments on unmanned platforms, e.g. AERONET-OC and RADCALNET, has proved to be the most effective way to provide calibration and validation data for Copernicus optical missions. The re-use of data from each site for many optical missions (S2, S3, MODIS, VIIRS, L8, Pléiades, ENMAP, PRISMA, SABIAMAR, etc.) gives a huge economy of scale. The existing AERONET-OC and RADCALNET networks are based on multispectral instruments; however these are expensive to acquire and require modelling of the associated uncertainties to cover all spectral bands of all sensors. Recent advances in opto-electronics facilitate the use of miniaturized hyperspectral spectrometers with reduced price. Industrial production of video surveillance cameras greatly reduces the price of pointing systems for scientific instruments. Improved LEDs provide a stable light source for relative calibration and continuous autonomous monitoring of radiometers. Webcams (for remote inspection of instruments and maintenance support) and data transmission have become cheaper reducing the running costs and improving the reliability of autonomous instrument systems. The general objectives of the HYPERNETS project were to (1) develop a new lower cost hyperspectral radiometer and associated pointing system along with an embedded calibration device for automated measurements of water and land bidirectional reflectance, and (2) provide high quality in situ measurements at all spectral bands for the validation of the surface reflectance data issued from all optical Copernicus missions. The instrument is tested in a prototype network covering a wide range of water types, land types, and operating conditions. Quality controlled data with associated uncertainty estimates are provided automatically. In addition to the development of the HYPERNETS instrument and system, preparations are made for (1) the new instrument design (and associated calibration service) to be commercialized with an expected lifetime of at least 10 years and (2) the networks to be further expanded to become the main source of surface reflectance validation data for all spectral bands of all optical missions for at least the next 10 years.
The user requirements for the instrument- and system design, as well as for the in situ data for validation of land and water reflectance were defined by extensive consultation. These requirements were used as the basis for the design concept (Fig. 1) of the instrument, system and network, and subsequently for the development and refinements of the HYPERNETS instrument and system (Fig. 2), and prototype network.
A new hyperspectral radiometer, the HYPSTAR®, has been designed based on an innovative design, combining high performance and moderate cost. Various optical components were tested and a final selection was made based on actual performance with respect to the user requirements. A first batch of 7 radiometers (Fig. 3) was constructed and delivered to partners for testing and performance evaluation. Using feedback from partners to improve the design, a second batch of 7 radiometers and a final batch of 17 radiometers (Fig 4) were constructed and delivered.
The new HYPSTAR® radiometer is embedded within the HYPERNETS host system, which integrates radiometer pointing, data acquisition and data transmission via a rugged PC and includes auxiliary sensors (rain, GPS, etc.) and site-specific power management. A first batch of 7 host systems was constructed and delivered to partners for testing and performance evaluation. Using feedback from partners to improve the design, a second and a third batch of host systems was delivered to partners.
A demonstration video (https://youtu.be/dfUAPYxg5Cc) has been produced for users showing the HYPSTAR® radiometer and host system.
The HYPERNETS network processor software receives data acquired by instruments in the field and processes to the level of water and surface reflectance with their uncertainties (Fig 5). This software integrates closely land and water processing branches and is now functioning in prototype form for automated daily processing of the data from the validation sites.
The HYPSTAR® radiometer and host system have been tested at 8 water (Fig. 6) and 12 land sites (Fig 7) covering a wide range of biogeophysical and environmental conditions. These validation sites form the core of a network that is appropriate for long-term radiometric validation of all optical imaging satellite missions.
HYPERNETS is now a well-known project throughout the international land and water remote sensing community, including the space agencies and validation entities. The project consortium has been very active in promoting the project by presenting the main objectives of the project at different meetings, conferences and other events. The user need is clear and the community is now waiting for this new instrument to become mature and commercially available.
A new hyperspectral radiometer, the HYPSTAR®, has been designed based on an innovative design, combining high performance and moderate cost. Various optical components were tested and a final selection was made based on actual performance with respect to the user requirements. A first batch of 7 radiometers (Fig. 3) was constructed and delivered to partners for testing and performance evaluation. Using feedback from partners to improve the design, a second batch of 7 radiometers and a final batch of 17 radiometers (Fig 4) were constructed and delivered.
The new HYPSTAR® radiometer is embedded within the HYPERNETS host system, which integrates radiometer pointing, data acquisition and data transmission via a rugged PC and includes auxiliary sensors (rain, GPS, etc.) and site-specific power management. A first batch of 7 host systems was constructed and delivered to partners for testing and performance evaluation. Using feedback from partners to improve the design, a second and a third batch of host systems was delivered to partners.
A demonstration video (https://youtu.be/dfUAPYxg5Cc) has been produced for users showing the HYPSTAR® radiometer and host system.
The HYPERNETS network processor software receives data acquired by instruments in the field and processes to the level of water and surface reflectance with their uncertainties (Fig 5). This software integrates closely land and water processing branches and is now functioning in prototype form for automated daily processing of the data from the validation sites.
The HYPSTAR® radiometer and host system have been tested at 8 water (Fig. 6) and 12 land sites (Fig 7) covering a wide range of biogeophysical and environmental conditions. These validation sites form the core of a network that is appropriate for long-term radiometric validation of all optical imaging satellite missions.
HYPERNETS is now a well-known project throughout the international land and water remote sensing community, including the space agencies and validation entities. The project consortium has been very active in promoting the project by presenting the main objectives of the project at different meetings, conferences and other events. The user need is clear and the community is now waiting for this new instrument to become mature and commercially available.
The new HYPSTAR® radiometer (https://hypstar.eu) is designed to have enhanced performance and a competitive price with respect to existing commercially-available radiometers thanks to the use of new opto-electronic components and careful design for the needs of radiometric validation. The instrument is intended to become the worldwide market leader for radiometric validation activities for the next 10 years.
The network of water and land sites where the instrument is being tested will give significantly more useful data than comparable existing networks, for example providing hyperspectral data for validation of all optical bands on all satellite missions instead of the current limited number of multispectral bands available from the AERONET-OC network. With its multi-site, multi-mission, all-band approach HYPERNETS aims to surpass the already impressive achievements of the AERONET-OC network for water reflectance validation and will reproduce this success for land reflectance validation over diverse surface conditions not currently covered by RadCalNet.
Space agencies and related validation entities have confirmed, when HYPERNETS was mentioned or presented during meetings, workshops or other events, the need for hyperspectral validation data, in particular, for the validation of the next generation of hyperspectral sensors (PRISMA, ENMAP, CHIME, PACE ...) but also for existing broadband sensors (Sentinel-2/MSI, Landsat-8/9, Planetscope/Doves …). Early results, using HYPERNETS data for the validation of the Sentinel-3/OLCI WFR product and CMEMS MULTI L3 MED water reflectance product and water and land surface reflectances from Sentinel-2 and Landsat-8/9 suggest that the instrument is fit for this purpose. The radiometer has also been used to estimate top of atmosphere reflectance at the Gobabeb and Antarctica sites at seems suitable also for vicarious calibration applications.
As a spin-off application, data from one validation site has been found useful for direct monitoring of algae in a drinking water reservoir (https://doi.org/10.3390/rs14215607) thus expanding the user community/customer base for the instrument and the data.
Full scientific results of the project will appear in a Special Issue of the journal Frontiers in Remote Sensing on “Optical Radiometry and Satellite Validation” (https://www.frontiersin.org/research-topics/55073/optical-radiometry-and-satellite-validation).
The first datasets from the project are distributed via ZENODO.
The network of water and land sites where the instrument is being tested will give significantly more useful data than comparable existing networks, for example providing hyperspectral data for validation of all optical bands on all satellite missions instead of the current limited number of multispectral bands available from the AERONET-OC network. With its multi-site, multi-mission, all-band approach HYPERNETS aims to surpass the already impressive achievements of the AERONET-OC network for water reflectance validation and will reproduce this success for land reflectance validation over diverse surface conditions not currently covered by RadCalNet.
Space agencies and related validation entities have confirmed, when HYPERNETS was mentioned or presented during meetings, workshops or other events, the need for hyperspectral validation data, in particular, for the validation of the next generation of hyperspectral sensors (PRISMA, ENMAP, CHIME, PACE ...) but also for existing broadband sensors (Sentinel-2/MSI, Landsat-8/9, Planetscope/Doves …). Early results, using HYPERNETS data for the validation of the Sentinel-3/OLCI WFR product and CMEMS MULTI L3 MED water reflectance product and water and land surface reflectances from Sentinel-2 and Landsat-8/9 suggest that the instrument is fit for this purpose. The radiometer has also been used to estimate top of atmosphere reflectance at the Gobabeb and Antarctica sites at seems suitable also for vicarious calibration applications.
As a spin-off application, data from one validation site has been found useful for direct monitoring of algae in a drinking water reservoir (https://doi.org/10.3390/rs14215607) thus expanding the user community/customer base for the instrument and the data.
Full scientific results of the project will appear in a Special Issue of the journal Frontiers in Remote Sensing on “Optical Radiometry and Satellite Validation” (https://www.frontiersin.org/research-topics/55073/optical-radiometry-and-satellite-validation).
The first datasets from the project are distributed via ZENODO.