Philippe Goryl

Radiometric, Geometric, and Image Quality Assessment of ALOS AVNIR-2 and PRISM Sensors

The Advanced Land Observing Satellite (ALOS) was launched on January 24, 2006, by a Japan Aerospace Exploration Agency (JAXA) H-IIA launcher. It carries three remote-sensing sensors: 1) the Advanced Visible and Near-Infrared Radiometer type 2 (AVNIR-2); 2) the Panchromatic Remote-Sensing Instrument for Stereo Mapping (PRISM); and 3) the Phased-Array type L-band Synthetic Aperture Radar (PALSAR). Within the framework of ALOS Data European Node, as part of the European Space Agency (ESA), the European Space Research Institute worked alongside JAXA to provide contributions to the ALOS commissioning phase plan. This paper summarizes the strategy that was adopted by ESA to define and implement a data verification plan for missions operated by external agencies; these missions are classified by the ESA as third-party missions. The ESA was supported in the design and execution of this plan by GAEL Consultant. The verification of ALOS optical data from PRISM and AVNIR-2 sensors was initiated 4 months after satellite launch, and a team of principal investigators assembled to provide technical expertise. This paper includes a description of the verification plan and summarizes the methodologies that were used for radiometric, geometric, and image quality assessment. The successful completion of the commissioning phase has led to the sensors being declared fit for operations. The consolidated measurements indicate that the radiometric calibration of the AVNIR-2 sensor is stable and agrees with the Landsat-7 Enhanced Thematic Mapper Plus and the Envisat MEdium-Resolution Imaging Spectrometer calibration. The geometrical accuracy of PRISM and AVNIR-2 products improved significantly and remains under control. The PRISM modulation transfer function is monitored for improved characterization.

Preliminary radiometric calibration assessment of ALOS AVNIR-2

This paper summarizes the activities carried out in the frame of the data quality activities of the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) sensor onboard the Advanced Land Observing Satellite (ALOS). Assessment of the radiometric calibration of the AVNIR-2 multi-spectral imager is achieved via three intercomparisons to currently flying sensors over the Libyan desert, during the first year of operation. All three methodologies indicate a slight underestimation of AVNIR-2 in band 1 by 4 to 7 % with respect to other sensors radiometric scale. Band 2 does not show any obvious bias. Results for band 3 are affected by saturation due to inappropriate gain setting. Two methodologies indicate no significant bias in band 4. Preliminary results indicate possible degradations of the AVNIR-2 channels, which, when modeled as an exponentially decreasing functions, have time constants of respectively 13.2 %.year-1, 8.8 %.year-1 and 0.1 %.year-1 in band 1, 2 and 4 (with respect to the radiometric scale of the MEdium Resolution Imaging Spectrometer, MERIS). Longer time series of AVNIR-2 data are needed to draw final conclusions.

The contribution of the european space agency to the ALOS PRISM / commissioning phase

The Advanced Land Observing Satellite (ALOS) was launched on Jan 24th, 2006 by a Japan Aerospace Exploration Agency (JAXA) H-IIA launcher. It carries three remote sensing instruments: Advanced Visible and Near Infrared Radiometer type-2 (AVNIR-2), Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) and Phased Array Type L-band Synthetic Aperture Radar (PALSAR). Within the framework of European ALOS Data European Node (ADEN), European Space Research INstitute (ESRIN) as part of European Space Agency (ESA), teamed up with JAXA for contributing to ALOS commissioning phase plan. This paper summarizes the strategy that ESA adopted to define and implement a data verification plan for mission operated by foreign nation, classified as so called ESA Third Party Missions (TPM). The verification of ALOS optical data from PRISM / AVNIR-2 instruments activities had begun four months after satellite launch on March 2007.GAEL Consultant (French company) has supported ESA / ESRIN for designing and executing the plan. A team of principal investigators has been put together to provide technical expertise. This paper includes a description of the verification plan and summarizes the methodologies that were used for radiometric, geometric and image quality assessment. Preliminary results indicate that the radiometric calibration of the AVNIR-2 sensor agrees with Landsat 5 (L5) Thematic Mapper and the MEdium Resolution Imaging Spectrometer (MERIS) calibration to within 10%. The geometry accuracy of PRISM and AVNIR-2 product remains within specifications but some recommendations are provided to improve the quality of product. The preliminary results from the PRISM image quality assessment through computation of PRISM Modulation Transfer Function (MTF) raised few questions toward jpeg compression that degrades image.

PROBA-V Mission Exploitation Platform

As an extension of the PROBA-Vegetation (PROBA-V) user segment, the European Space Agency (ESA), de Vlaamse Instelling voor Technologisch Onderzoek (VITO), and partners TRASYS and Spacebel developed an operational Mission Exploitation Platform (MEP) to drastically improve the exploitation of the PROBA-V Earth Observation (EO) data archive, the archive from the historical SPOT-VEGETATION mission, and derived products by researchers, service providers, and thematic users. The analysis of the time series of data (petabyte range) is addressed, as well as the large scale on-demand processing of the complete archive, including near real-time data. The platform consists of a private cloud environment, a Hadoop-based processing environment and a data manager. Several applications are released to the users, e.g., a full resolution viewing service, a time series viewer, pre-defined on-demand processing chains, and virtual machines with powerful tools and access to the data. After an initial release in January 2016 a research platform was deployed gradually, allowing users to design, debug, and test applications on the platform. From the PROBA-V MEP, access to, e.g., Sentinel-2 and Sentinel-3 data will be addressed as well.

GMES Sentinel-3: Mission Overview and Aspects of the Calval Plan for its Optical Payload

The European Union-ESA Global Monitoring for Environment and Security (GMES) programme decided to develop the Sentinels as first series of operational satellites in order to meet specific Earth observation user needs. The series of Sentinel-3 satellites will provide global, frequent and near-realtime ocean, ice and land monitoring. It continues Envisats altimetry, the multispectral, medium-resolution visible and infrared ocean and land-surface observations of ERS, Envisat and Spot, and includes enhancements to meet the operational revisit requirements and to facilitate new products and evolution of services. The first launch is expected in 2013. In this paper an outline of the Sentinel-3 satellite and optical payload is presented. Dedicated calibration and validation activities regarding the sea and land surface temperature radiometer (SLSTR) and ocean and land colour radiometer (OLCI) are then reviewed. Calibration and validation (calval) activities are based on the heritage gained from ENVISAT MERIS and AATSR experience and cover pre-launch, in-orbit commissioning and operational measures for the Sentinel 3 satellites.

European Space agency (ESA) Landsat MSS/TM/ETM+/OLI archive: 42 years of our history

Whilst recent years have witnessed the development and exploitation of operational Earth Observation (EO) satellite constellation data, the valorisation of historical archives has been a challenge. The ESA Multi Spectral Scanner (MSS) products cover Greenland, Iceland, Continental Europe and North Africa representing an archive of over 600,000 Level 1 (L1) scenes that join the 1 million ESA Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) products already available. This paper presents the L1 MSS product functionality, and how the dataset will be fit for multi temporal purposes. For example, a quality assurance traceability concept is implemented through an innovative pixel based Quality Assurance Band (BQA) that includes land, cloud and anomaly flagging. Land cover application areas are showcased, including vegetation monitoring and snow cover monitoring on glaciers.

Bulk reprocessing of the ALOS PRISM/AVNIR-2 archive of the European Space Agency: Level 1 Orthorectified Data processing and Data Quality Evaluation

The Advanced Land Observing Satellite (ALOS) was launched on January 24, 2006, by a Japan Aerospace Exploration Agency (JAXA) H-IIA launcher. It carries three remote sensing sensors: the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2), the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), and the Phased Array type L-band Synthetic Aperture Radar (PALSAR). Within the framework of ALOS Data European Node (ADEN), as part of the European Space Agency (ESA), has collected 5 years of data observed in Arctic, in Europe and in Africa through the ground stations of Tromsoe (Norway) and Matera (Italy). Some data has been repatriated directly from JAXA from the on-board recorder (in particular over Africa, outside the visibility of the stations). The data were available to the scientific users via on-request ordering from the stations through the ESA ordering system. In ordering to provide a better and easier access to the data in the framework of the ESA Third Party Missions, in 2015 ESA started a project aimed to repatriate the data from the stations, consolidate them, harmonise the format to the ESA standards. For the PALSAR data, view the different processing levels available to the users, ESA decided to setup a dissemination system, able to process automatically at the user demand the data to the requested level (on-the-fly processing). For the optical data, instead, the decision was to systematically process the PRISM and AVNIR-2 as orthorectified products (so to a higher level in respect of what available before) with a systematic quality control. This paper presents the functionalities of the new Level 1 orthorectified products and details the block adjustment algorithms used for refinement of geometric accuracy. A specific quality control strategy has been laid down in order to re-analyse the entire archive. Also, validation methods are explained and the final product accuracy specification are given.

Sentinel-3: Mission status and performance after one year in orbit

The Copernicus Programme, being Europes Earth Observation and Monitoring Programme led by the European Union, aims to provide, on a sustainable basis, reliable and timely services related to environmental and security issues. The Copernicus Programme uses multiple source data and comprises a service component, a space infrastructure component and an in-situ component. The objective of the Copernicus Space Component (CSC) Programme is to fulfil the space-based observation requirements in response to European policy priorities with a particular emphasis on the Copernicus core services as identified by the Commission. It aims at developing a fully operational capability in view of feeding Copernicus services with satellite data. The CSC Programme also aims at the operational provision of satellite data for other European and national services. The main data source for the CSC Programme are the Sentinels, dedicated missions providing continuity to past or present data sets. In addition, the CSC Programme covers the development and operations of a Data Access Layer, the Coordinated Data System (CDS), aiming at providing Copernicus Services with satellite data from other than Sentinel missions (ESA, National, EUMETSAT and other Third Party Missions) of relevance to the overall space component of Copernicus.

Status of copernicus Sentinel-2A and Sentinel-3A optical calibration and validation activities

The Copernicus Programme, being Europes Earth Observation and Environment Monitoring Programme led by the European Union, aims to provide, on a sustainable basis, reliable and timely services related to environmental and security issues. The Copernicus Programme uses multiple source data and comprises a service component, a space infrastructure component and an in-situ component. The objective of the Copernicus Space Component (CSC) Programme is to fulfil the space-based observation requirements in response to European policy priorities with a particular emphasis on the Copernicus core services as identified by the European Commission. It aims at developing a fully operational capability in view of feeding Copernicus services with satellite data. The CSC Programme also aims at the operational provision of satellite data for other European and national services. The main data source for the CSC Programme are the Sentinels, dedicated missions providing continuity to past or present data sets. In addition, the CSC Programme covers the development and operations of a Data Access Layer, the Coordinated Data access System (CDS), aiming at providing Copernicus Services also with satellite data from other missions (by ESA, National, EUMETSAT and other Third Party Missions) that are of relevance to the overall space component of Copernicus.

Bulk processing of the Landsat MSS/TM/ETM+ archive of the European Space Agency: an insight into the level 1 MSS processing

Whilst recent years have witnessed the development and exploitation of operational Earth Observation (EO) satellite constellation data, the valorisation of historical archives has been a challenge. The European Space Agency (ESA) Landsat Multi Spectral Scanner (MSS) products cover Greenland, Iceland, Continental Europe and North Africa represent an archive of over 600,000 processed Level 1 (L1) scenes that will accompany around 1 million ESA Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) products already available. ESA began acquiring MSS data in 1975 and it is well known that this dataset can be degraded due to missing data and a loss in accuracy. For these reasons, the content of the product format has been reviewed and the ESA Landsat processing baseline significantly updated to ensure products are fit for user purposes. This paper presents the new MSS product format including the updated metadata parameters for error traceability, and the specification of the Quality Assurance Band (BQA) engineered to allow the best pixel selection and also the application of image restoration techniques. This paper also discusses major improvements applied to the radiometric and geometric processing. For the benefits of the community, ESA is now able to maximize the number of L1 MSS products that can potentially be generated from the raw Level 0 (L0) data and ensure the highest possible data quality is reached. Also, by improving product format, processing and adding a pixel based quality band, the MSS archive becomes interoperable with recently reprocessed Landsat data and that from live missions by way of assuring product quality on a pixel basis.