Sentinel Collaborative Ground Segment Sweden

Transcription

1 Sentinel Collaborative Ground Segment Sweden User needs Final Report Photo: ESA Sentinel Collaborative Ground Segment Sweden User needs Coverage, Products and Services Final Report Study for the Swedish National Space Board December 2014 Document ID Version MET CGSS MS Change record Version Date Author Mats Rosengren First version Corrected version 1 MET CGSS MS v1.1 Metria AB

2 Metria AB, Box 30016, Stockholm BESÖKSADRESS : Warfvinges väg 35 TEL FAX E POST mats.rosengren@metria.se WEBB 2 MET CGSS MS v1.1

3 0 Executive Summary In April 2014, ESA presented its plans regarding the future Swedish user access to Sentinel data to the Swedish National Space Board (SNSB). Subsequent discussions led to the SNSB entrusting Metria and Spacemetric with the task to produce a report regarding Swedish needs for Sentinel data, and the technical solutions necessitated by these needs. Broadly speaking, Metria was given the brief to investigate the needs, whilst Spacemetric was asked to shed light on the more technical aspects. This document is the result of Metria s work to collect and analyse the needs and requirements from the Swedish potential user community of Sentinel data. The difficulties of collecting and condense the descriptions of all Sentinel 1, 2 and 3 products and access conditions forced us to change the idea of collecting user requirements through a systematic sent out survey of user needs and requirements. Instead, by interviewing an as far as possible representative selection of potential user organisations covering the full scale from research, mapping and monitoring to downstream users of mapping and analysis results and imagery; from land to marine applications; from NRT daily use of satellite data to users of yearly coverages. The collected information from these interviews have been the starting point for a preliminary analysis of user needs and requirements concerning geographic coverage areas of interest and the type of products requested. We have been able to summarise the basic characteristics of data and products provided by ESA's Sentinel Core Ground Segment and how the establishment of a Swedish Sentinel Collaborative Ground Segment (CGSS) will further enhance the possibilities for using the Sentinel products and services by better meeting the specific user needs collected from potential Swedish Sentinel data users. Issues concerning differences between user categories to access data in a timely manner (NRT data), access to the long term archive, data quality, data amounts, locally adapted data, higher processing levels, user friendly formats and services are described. It is recommended that after the completion of this report, a user survey should be sent out to a wider community of potential users with a condensed description of the Sentinel system, missions, sensors and products for informing the potential users of what we can expect in the near future. The continued work of defining in more detail the list of products and services to implement and the data acquisition scenarios concerning geographic areas of interest must be based on the results of this survey. One immediate conclusion drawn from the information collected is that a consequence of the architecture and access restrictions of the Core Data Hub System chosen by ESA, there seems to be no alternative other than as soon as the Sentinel 1 data access become operational, setting up as a minimum a national Swedish Data Hub Mirror site in order to secure long term archiving and access to all data covering a Swedish geographical area of interest for the support of Swedish users. This must also be ready in time for Sentinel 2 data when operational. A CGSS should at a minimum be able to perform automatic daily downloads, cataloging and archiving of new data according to predefined criteria and provide an interface searching and delivering copies of downloaded products to Swedish users. The functionality of the CGSS should from a user perspective be implemented in several functional stages starting with basic time critical functions as these is a need of having the first basic parts of the system operational very soon before the complete system is specified in detail. There is also a need to start development of some advanced functions required for the implementation of automated data preparation for monitoring and change detection purposes such as automatic methods for delineating clouds and cloud shadows, which is a major problem and a key issue to solve to enable future automatic monitoring services. Other key elements for the full use of Sentinel data are operational atmospheric correction into L2 products and tools for 3 MET CGSS MS v1.1

4 preparation of time series data from archived data. The Sentinel Toolbox methods for atmospheric correction and the MACCS software should be evaluated for this. The feasibility to including NTR products from Sentinel 1 and Sentinel 3 from EUMETSAT and Collaborative Ground Stations in the CGSS should be investigated and compared to alternative solutions. Alternatives for the future handling of Saccess data within CGSS or not should be investigated. The inclusion of other similar satellite data such as Landsat 8 should be considered. The governance of the CGSS is a key issue that must encompass the overall goals and responsibilities of the initiative. It is recommended the Swedish National Space Board lead the work needed to define the roles and responsibilities of such a governing body. Further it is recommended that options be investigated for the potential form of such a governing body, including the creation of a public/industry consortium. 4 MET CGSS MS v1.1

5 Table of Contents 0 Executive Summary 1 Introduction 2 Definitions, acronyms and abbreviations 3 Reference documents 4 Background 4.1 Study instructions 4.2 The Sentinel Missions 4.3 Saccess 5 Sentinel Satellites and Sensors 5.1 Sentinel Sentinel Sentinel 3 6 ESA Core Ground Segment and Data Access 6.1 Sentinel Data Acquisition 6.2 Data Access Infrastructure 6.4 Collaborative Ground Segment Mirrors 6.5 Sentinel Toolboxes Sentinel 1 Toolbox Sentinel 2 Toolbox Sentinel 3 Toolbox 7 Current Use of Satellite Data 7.1 Current Use of Optical HR Data Sentinel 2 Type Data 7.2 Current Use of SAR Data Sentinel 1 Type Data 7.3 Current Use of Optical LR Data Sentinel 3 Type Data 8 Swedish User Needs and Requirements 8.2 User Categories 8.3 Generalised Swedish Users Needs and Requirements of Sentinel Data Geographic Areas of Interest Delivery time requirements Product preprocessing levels Sentinel 2 Sentinel 1 Sentinel Summary of User Needs of Sentinel Product Types Amounts of data to archive Future Saccess Data Availability 8.6 Implementation Scenario CGSS Potential Functional Blocks in a Swedish CGSS Recommendations for Implementation Steps in Preparation for a Swedish CGSS Needs for Development for Operational Requirements Recommendations Handling of NRT data and EUMETSAT Sentinel 3 Products Recommendations 8.7 Governance/system ownership and operations management Background Discussion Recommendations 5 MET CGSS MS v1.1

6 1 Introduction This document is the result of Metria s work trying to summarise and give an overview of the basic characteristics of data and products provided by ESA's Sentinel Core Ground Segment and how the establishment of a Swedish Sentinel Collaborative Ground Segment could further enhance the possibilities for using the Sentinel products and services by better meeting the specific user needs collected from potential Swedish Sentinel data users. Issues concerning differences between user categories to access data in a timely manner (NRT data), access to the long term archive, data quality, data amounts, locally adapted data, higher processing levels, user friendly formats and services are described. The themes covered are: Basic characteristics of the Sentinel satellites and their sensors Overview of standard products provided by ESA Core Ground Segment Data access alternatives and limitations for different user categories Swedish user needs of data and products Potential list of functions within a Swedish Collaborative Ground Segment The texts are intended to be used as a basis for decisions on data collection and archiving strategies and the definition of products and services to be provided by the Swedish part of the collaborative ground segment. 2 Definitions, acronyms and abbreviations BOA Bottom Of Atmosphere CCM Copernicus Contributing Mission CGS ESA Core Ground Stations CGS Collaborative Ground Segment CGSS Collaborative Ground Segment Sweden CLC Corine Land Cover CSC Copernicus Space Component CSCDA Copernicus Space Component Data Access CSC CGS Copernicus Space Component Core Ground Segment DAP Data Access Portfolio DEM Digital Elevation Model DHuS Data Hub System DTED Digital Terrain Elevation Data DTED1 Quality level indication DEM resolution of 90m (DTED2 is 30m) DWH Data WareHouse EEA European Environment Agency EMSA European Maritime Safety Agency ESA European Space Agency EO Earth Observation EU European Union EW Extra Wide Swath (Sentinel 1 SAR product) FTP File Transfer Protocol GB Gigabyte GCP Ground Control Point GIOLand GMES Initial Operation Land Services GIS Geographic Information System GMES Global Monitoring for Environment and Security (old name for Copernicus) GRD Ground Range Detected 6 MET CGSS MS v1.1

7 GSCCGS HaV HR HRL ICD IR IW KSAT LR MACCS MIR MS MSB MSI MWR NGO NIR NRT OCN OLCI PAC PDGS PDMC RPC S1,S2,S3 SACCESS SAR SIDA SLC SLSTR SLU SM SMHI SRAL SWaM SWIR TB TBC TBD TOA USGS UTM VEGA VIS VHR WCPS WCS WFS WMS Wv WWF GMES Space Component Collaborative Ground Segment Havs och Vattenmyndigheten High Resolution (often meaning 10m 50m resolution) High Resolution Layers of the GIOLand Interface Control Document InfraRed Interferometric Wide Swath (Sentinel 1 SAR product) Kongsberg Satellite Services AS Low Resolution (> 50m resolution) Multisensor Atmospheric Correction and Cloud Screening processor Middle Infra Red (also called SWIR) Member State Myndigheten för samhällsskydd och beredskap / Swedish Civil Contingencies Agency Multi Spectral Imager (on Sentinel 2) MicroWave Radiometer (on Sentinel 3) Non governmental organization Near InfraRed Near Real Time Ocean Ocean Land Colour Instrument Processing and Archiving Centre Payload Data Ground Segment Payload Data Management Centre Rational Polynomial Coefficients Sentinel 1, Sentinel 2, Sentinel 3 Swedish National Satellite Image Database Synthetic Aperture Radar (on Sentinel 1) The Swedish International Development Cooperation Agency Single Look Complex Sea and Land Surface Temperature Radiometer (on Sentinel 3) Swedish University of Agricultural Sciences Strip Map (Sentinel 1 product) Swedish Meteorological and Hydrological Institute SAR Altimeter (on Sentinel 3) Swedish Agency for Marine and Water Management (Havs och vattenmyndigheten) Short Wave Infra Red (also called MIR) Terabyte To Be Confirmed To Be Defined Top Of Atmosphere US Geological Survey Universal Transverse Mercator map projection Vettore Europeo di Generazione Avanzata, ESA Launch Vehicle Visible Very High Resolution ( =< 5m resolution) Web Coverage Processing Service Web Coverage Service (raster data) Web Feature Service (vector data) Web Map Service (raster map) Wave (Sentinel 1 SAR product) World Wildlife Fund 7 MET CGSS MS v1.1

8 3 Reference documents [RD 1] Sentinel Overview and Status, Meeting with Swedish Partners, 18 March 2014 [RD 2] Copernicus Space Component Collaborative Data Access Data Hub Mirror Site Interfaces, J. Martin, European Space Agency, 18 March 2014 [RD 3] Dnr : 62/14, Beställning av utredning av den svenska delen av det samverkande marksegmentet för Copernicus Sentineldata, SNSB [RD 4] Preparations for acquisition and application of optical satellite data for Norway Digital Part 2, Report ANB 11 05, Kartverket Norge, March 2014 [RD 5] Forberede mottak og anvendelse av optiske satellittdata for Norge digitalt ANB11 05, Jon Arne Trollvik, Statens kartverk; Arnt Kr Gjertsen, Norsk institutt for skog og landskap; Kai Sørensen, Norsk institutt for vannforskning; Ragnvald Larsen, Direktoratet for naturforvaltning, June 2012 [RD 6] Way forward to establishing the Collaborative Ground Segment Agreements for the Sentinels National Utilisation by ESA Participating States, ESA/PB EO(2013)19. Paris, 22 April 2013 [RD 7] [RD 8] 8 MET CGSS MS v1.1

9 4 Background 4.1 Study instructions The purpose of this study is to clarify Swedish user needs and requirements on data from Sentinel 1, 2 and 3 with emphasis on the acquisition, archiving and dissemination of data of specific value for Sweden. The areas to cover by the study: Investigate the specific product and service adaptations required to meet local and national user needs are not met by the ESA Core Ground Segment (CGS) together with the needs for the Remote Sensing research in Sweden for data suitable for time series analysis. Identify which datasets/product levels to download and archive in the Swedish CGSS. Identify how national projections, DEMs and cloud masking should be applied. For this purpose the study should describe alternative solutions available from different parties such as ESA. Consult and interview Swedish potential users of Sentinel data for research and operational applications. Show how the needs for research organisations can be met. Take into account the needs and requirements of the downstream services industry. Give an overview of national plans and current developments for Collaborative Ground Segment components in other European countries and indicate the feasibility of collaborative data sharing solutions. Estimate costs of development, establishing, operation, service and maintenance of alternative solutions. 4.2 The Sentinel Missions The European Sentinel constellation of satellites is developed for continuously providing systematic global Earth Observation data to the EU funded Copernicus operational services. The Sentinel programme is planned to be the long term operational solution for this task reaching beyond The decision at the political level has been made to offer all Sentinel data with the free, full and open data policy adopted for the Copernicus programme. This means that in addition to the primary task for ESA of providing data to the Copernicus Services, all other categories of users will now be given access to the data. Due to the separate funding mechanism, the original Sentinel Core Ground Segment did not include the capacity and mechanisms to give all other users access to the Sentinel data products. In order to give access to all users, four different user categories have been defined with different access conditions. Specifically, ESA and EU Member States have the possibility of joining a Sentinel Collaborative Ground Segment where each country has one central access point, a national Collaborative Ground Segment Mirror site, to a rolling archive (DHuS) of the ESA Core Ground Segment or setting up a local Ground Receiving Station for fast access to data. The local components of the Collaborative Ground Segment must be financed separately by Member States. The land and ocean monitoring missions of the Sentinel constellation are Sentinel 1, Sentinel 2 and Sentinel 3 which all are operated in polar orbits. Additional Sentinel missions are focused on atmospheric monitoring and sea surface height and are not further described in this study. Sentinel 1 is an all weather SAR radar satellite for land and sea monitoring. Sentinel 1A is the first of all Sentinel missions in orbit launched 3 april Sentinel 2 carries an optical multispectral sensor for the monitoring of land, coastal and inland waters. The Sentinel 2 mission combines a unique set of features; systematic acquisition of all land surfaces and coastal water; high revisit frequency (5 days periodicity); large swath (290 km); high spatial resolution (10m / 20m / 60m) and large number of spectral bands (13 bands in VNIR SWIR). Sentinel 2 will cover all of Sweden twice per week which will increase the number of usable cloud free images. 9 MET CGSS MS v1.1

10 Sentinel 3 carries several instruments for global monitoring of land, oceans and sea waters and measures land and water surface temperatures, sediments, chlorophyll and algae blooms but also the sea surface topography. 4.3 Saccess The last years, a number of semi operational and operational services have been introduced based on spaceborne SAR, Optical High Resolution and Optical Low Resolution image data. Saccess, the national Swedish Satellite Data Archive facility opened in 2008 is providing free yearly national coverages of optical high resolution image data from SPOT, IRS and Landsat to any user living in Sweden, Norway, Finland or Denmark for any purpose. In an European context, this is a unique service compared to any other national initiatives. Saccess data is required to carry out the operational tasks of the Swedish Forest Agency for nationwide monitoring of clear felled areas. Other examples of nationwide uses are the KNN forest estimates produced by SLU and the mapping of protected areas (KNAS) produced by Metria for the Environmental Protection Agency. In spite of the widespread access to data through Saccess, the lack of cloud free images from optimal dates has been a severely limiting factor for a wider operational use of optical high resolution data in Sweden. 5 Sentinel Satellites and Sensors A Swedish CGSS is primarily aimed for handling data from Sentinel 1, 2 and 3. These satellites are all operated in polar orbits at altitudes between 693 and 815 km and will systematically have global data coverage with a cycle of 2 5 days for a complete coverage, different depending on sensor and swath width. For each Sentinel there will be 2 satellites in simultaneous operation. When all 6 satellites are in orbit and fully operational they will generate and downlink c. 4 TB raw data per day for the global coverage. All downlinked and archived data will be systematically preprocessed into a list of higher level products which also will be archived by the ESA Core Ground Segment. The systematically produced user products and the raw data cause the ESA archive to increase by approximately 10 TB per day with an annual growth rate of 3 4 Petabytes ( TB). The Swedish CGSS archive will grow by TB per year, depending on the list of products to store and the size of the geographic coverage area. Table 1 below summarizes the basic characteristics of the three Sentinel satellite systems. Satellite Launch Sensors Applications Revist cycle (2 satellites) Orbital altitude Sentinel 1A SAR C band > 5 m resolution Sentinel 1B 2016 < 400 km swath Sentinel 2A ( ) Sentinel 2B 2016 MSI: (13 bands vis/nir/swir) m resolution 290 km swath Sentinel 3A Sentinel-3B OLCI: 21 bands Ocean colour, Atmosphere, 300 m resolution SLSTR: Surface temp, 500 m SRAL: (SAR altimeter) Sentinel-3C 2020 MWR: (MW radiometer) Land and Ocean monitoring. Sea Ice, Land Interferometry Land monitoring Lakes Coastal waters Marine applications Atmosphere Fire detection Land vegetation phenology 3 days (10 days for interferometry) 5 days (2 3 for Sweden) 2 3 days (1 2 for Sweden) 693 km 786 km km Table 1: Basic characteristics of the Sentinel missions More details are found at: operational eo missions/sentinel 1 future missions/sentinel 2 10 MET CGSS MS v1.1

11 future missions/sentinel Sentinel 1 SENTINEL 1 is a constellation of two radar satellites carrying a C band SAR as the primary sensor for Land and Ocean monitoring. The SAR offers medium and high resolution imaging in all weather conditions. It can be operated in four basic modes with different polarisations, resolution and swath widths. The normal configuration for land and ocean is the Interferometric Wide swath (IW) covering 250 km with 20m resolution. The flexibility of operating the sensor is handled by a mid term High Level Operations Plan that defines on an overall level the parts of the world in which the different sensor modes will be used. This plan is valid converted into the Sentinel 1 Operations Plan which is continuously defined and updated for each 12 day orbital cycle of Sentinel 1 Data is processed into a list of standard products optimised for meeting the requirements from different user types. These standard products are summarised in Figure 1 below. Figure 1: Sentinel-1 standard product overview These products will be available for download by users within 3 24 hours. High priority Copernicus Services such as MyOcean och EMSA (European Maritime Safety Agency) requiring fast delivery data (NRT, Near Real Time) will be served by the ESA Core Ground segment in less than 1 hour from data acquisition. All other users requiring fast delivery NRT data have to rely on getting the data through a local direct receiving Collaborative Ground station making it possible to distribute preprocessed data sets within 30 minutes for specific applications, such as SAR images for icebreaker operations. One such alternative for Swedish NRT data users could be through cooperation with the Sentinel 1 ground stations in Norway or Finland. 5.2 Sentinel 2 The Sentinel 2 satellites carry a multispectral high resolution optical sensor (Visible / NIR / SWIR) for land monitoring but also suitable for coastal and lake water monitoring. Sentinel 2 will also deliver information for emergency services. Sentinel 2 is a truly operational mission in which flexibility has been reduced in favor of systematic single mode operations enabling a guaranteed nadir looking, systematic coverage for all parts of the world. This will reduce the risk of missing opportunities for cloud free data over cloudy parts of the world by acquiring data from every overpass. With two satellites in operation the complete global land area will be imaged every 5 days. Sentinel 2 is unique by the combination of: 1. Systematic data acquisition over all continental land masses and large islands including coastal 11 MET CGSS MS v1.1

12 zones. 2. Short systematic revisit time with a 5 day cycle at the equator. At Swedish latitudes this is reduced to 3 days km imaging swath width. 4. High resolution (10m; 20m; 60m) spectral bands which also enables enhanced atmospheric correction. The list of standard product types proved by ESA Core Ground System is simple. Only two processing levels are produced. The products are described in Table 2 below. Product Description Production /Distribution Data Volume Level-1B * TOA-radiance sensor geometry Level-1C * TOA-reflectance Ortho corrected UTM-projection Systematic production Online distribution Systematic production Online distribution 27 MB / tile (25 x 23 km) 500 MB / tile (100 x 100 km UTM-projection) Level-2A Atmospheric corrected * BOA-reflectance Ortho corrected prototype product Sentinel-2 Toolbox Production by user or in national hub Table 2: Sentinel 2 standard products from ESA *TOA = Top Of Atmosphere *BOA = Bottom Of Atmosphere, i.e. atmospheric corrected ground reflectance 600 MB / tile (100 x 100 km UTM-projection) 5.3 Sentinel 3 The Sentinel 3 carries several sensors for observing land, water and atmosphere with a resolution suitable for near daily global coverage. The on board instruments are: Sea and Land Surface Temperature Radiometer (SLSTR) measuring temperatures with 500 m and 1 km resolution. Ocean and Land Colour Instrument (OLCI) multispectral measurement on land and water in 21 spectral bands with 300 m resolution. Synthetic Aperture Radar Altimeter (SRAL) measuring seas surface elevation / topography with 300 m resolution. The processing and distribution of Sentinel 3 standard products are handled by ESA mainly for land application products. The Sentinel 3 products list from ESA are listed in Table 3 below. Product Level Product Type Description OLCI Level 1B (21 bands) Radiometrically calibrated, geo referenced radiometrically calibrated, geo referenced and annotated radiances OLCI Level 2 Land Land and atmospheric geophysical products Global Vegetation Index (OGVI) Terrestrial Chlorophyll Index (OTCI) Integrated Water Vapour (IWV) column Rectified reflectance for red and MIR OLCI Level 2 Water Water and atmospheric geophysical products Surface directional reflectance (Rxxx) Chlorophyll a concentration (chl_oc4me; chl_nn) Total suspended matter concentration (TSM_NN) Quantum energy flux from the sun in the spectral range nm (PAR) Aerosol load, expressed in optical depth (T865; A865) 12 MET CGSS MS v1.1

13 Integrated Water Vapour (IWV) column SLSTR Level 1B Radiometrically calibrated, geo referenced TOA brightness temperatures TOA radiances SLSTR Level 2 WST Land and atmospheric geophysical products High Resolution Sea Surface Temperature SLSTR Level 2 LST Land geophysical product Land Surface Temperature (LST) SLSTR Level 2 FRP Fire Radiative Power Fire Radiative Power (FRP) values and associated parameters Table 3 : List of ESA Sentinel 3 standard products The responsibility and operations of the sentinel 3 Ground segment have been split between ESA and EUMETSAT. This in order to handle the distribution of products applicable for maritime, hydrological and meteorological use through the already existing network between the European weather services. EUMETSAT is mainly responsible for the Sentinel 3 water and atmospheric products, which are listed in Table 4 below. Instrument Level Product Description OLCI (Ocean Colour) 1 OL_1_EFR Full resolution Top of atmosphere radiance OLCI (Ocean Colour) 1 OL_1_ERR Reduced Resolution Top of atmosphere radiance OLCI (Ocean Colour) 2 OL_2_WFR Full resolution water and atmosphere parameters OLCI (Ocean Colour) 2 OL_2_WRR Reduced resolution water and atmosphere parameters SLSTR (Surface Temperature) 1 SL_1_RBT Brightness temperatures and radiances SLSTR (Surface Temperature) 2 SL_2_WST L2P Sea Surface Temperature SRAL (SAR Radar Altimeter) 2 SR_2_WAT 1 Hz and 20 Hz Ku and C bands parameters (LRM/SAR), waveforms over water Table 4 : List of EUMETSAT Sentinel 3 standard products At present, we have not been able to dig deeper into the specifications of the apparently overlapping products between ESA and EUMETSAT, especially when it comes to the OCLI Water products. It seems that the OLCI Level 2 Full resolution water and atmosphere products from EUMETSAT is very similar to the OLCI Level 2 Water product from ESA, maybe even identical? 13 MET CGSS MS v1.1

14 6 ESA Core Ground Segment and Data Access 6.1 Sentinel Data Acquisition The Sentinel data acquisitions from the satellites is performed through Sentinel Core Ground Stations in collaboration with Local Ground receiving stations. The Core Ground Stations are the front end component of ESA CSC Core Ground Segment which are responsible for data acquisition and near real time processing for the Copernicus Services. The data is transferred to the core production, archiving and retrieval systems and facilities for further processing and data handling. 6.2 Data Access Infrastructure The free, full and open data policy adopted for the Copernicus programme gives access for all types of users to the Sentinel data products. Users are grouped into four different categories having different data access channels and levels of priority concerning timeliness and data volumes. Figure 2 illustrates these access infrastructure channels for the four user categories which are in order of priority: Copernicus Services Member State Mirrors within the Collaborative Ground Segment International Mirrors within the Collaborative Ground Segment Scientific and Other users (including Commercial and Public Users Figure 2: ESA Core Ground Segment Data Access for different user categories The conditions of access valid for the different user types are further detailed in Table 5, with the most critical restrictions highlighted in red. This is the current situation as communicated through official channels. As it is identified that one key element missing is the access of scientific and other users to long term archived Sentinel data, it is possible that, depending on additional financing, the core ground segment will add this access point in the future. This is still an open question without any decisions made. 14 MET CGSS MS v1.1

15 User Category Free data access to: Access Points Copernicus Services ESA/EU MS National Use NRT/24h and consolidated Sentinels products Different missions archives, including long term On demand production Access via user available bandwidth to the Copernicus Space Component dissemination backbone EUMETCAST access for Sentinel 3 marine products Dedicated data sets generation (CORE DATASETS e.g. land coverage) Possibility of requesting on demand production (ADDITIONAL DATASETS) Full time access to emergency services (24h/7/365, incl. rush mode) (for authorized users) Service Desk support through dedicated user account management Copernicus Contributing Missions to specific Terms and Conditions Rolling Archive (2 months) of standard Sentinels products Access via user available bandwidth to a dedicated dissemination bandwidth Dedicated support for limited on request data set generation ESA & EUMETSAT catalogues & dedicated servers EUMETCAST services for Sentinel 3 Marine Rolling Archive Data Hub server Catalogue ftp & http downloads (bulk) Service commitment / comment Committed performances Targeted performances to support ESA/EU Member States Capacity to copy full global dataset Limited access to offline archive International Agreements Rolling Archive (2 months) of standard Sentinels products Access via user available bandwidth to a dedicated dissemination bandwidth Dedicated support for limited on request data set generation Rolling Archive Data Hub server Catalogue ftp & http downloads (bulk) EUMETCAST services for Sentinel 3 Marine Targeted performances to support EU International Agreements Scientific Use and Other Use (e.g. commercial, outreach, public) Dedicated rolling archive of a consolidated production baseline (products availability may be deferred ) Access via user available bandwidth to a dedicated dissemination bandwidth Access configured to avoid resources saturation resulting from massive downloads by a limited user community (e.g. maximum number of parallel downloads, maximum volume per retrieval, ) Rolling archive server Dedicated product discovery http downloads EUMETCAST services for Sentinel 3 Marine Shared and open resources for scientific and other use accesses Only Rolling Archive Table 5: Comparison between user types of applicable access conditions and list of accessible products and services In summary users will have four different access points: Copernicus Services having special access to Sentinel data including full on demand access to the archive (CSC Data Access) and the ability to request emergency programming of the Sentinel satellites. Member States Collaborative Access via the Data Hub System (DHuS) through a 2 month rolling archive with guaranteed access for the cooperating Member States (MS). The access to the infrastructure will be via the user available bandwidth to a dedicated dissemination bandwidth, this latter with committed reliability and performance. There will be no online access to archived data other than via requests for offline bulk delivery on a campaign basis. Each MS will be issued with a single username and password to 15 MET CGSS MS v1.1

16 enable a single entity to coordinate MS data access to a Collaborative Ground Segment Mirror. International Agreements Access will be achieved via a dedicated network. The data access will be to a rolling 2 month archive but not to the offline long term archive. Scientific/Other Users will have free and open access for research, commercial, outreach use and the general public. A rolling on line archive covering the last month(s) of selected Sentinels core products will be accessible This access is however, shared with all users of this category, spread around the globe likely to be large in number. For this reason there will be limitations on data volumes and number of parallel downloads to guarantee some level of data access to all users. Currently no mechanism has been implemented or planned for access to archived data (i.e. data older than the 2 months rolling archive). 6.4 Collaborative Ground Segment Mirrors National Collaborative Ground Segment systems are considered or planned to be set up in many of ESA and EU Member states. This in order to secure the long term archiving if Sentinel data over each Member States national territory but also to better support national users by NRT data through national local Ground Receiving Stations. For all users requiring NRT data outside Copernicus Core Services must rely on getting fast delivery data in parallel with the ESA Core Ground Segment. The formal situation is somewhat undefined at this moment, and we are still waiting for the final technical and financial solution to define and implement sufficient capacity and access systems into the ESA Core Ground Segment to provide all data requested by all types of users, including Scientific and Other users, with free, full and open access. With the current definition of the ESA Core Ground Segment, the MS Collaborative Mirrors are set up with the explicit motive to be able to have more flexibility and products adapted to local user requirements: Provide data to national users in a user friendly way faster than through the Scientific Hub of the ESA Core system, Provide subscription services to national users for automatic data dissemination. Secure and provide online access to archived data from a local long term local archive, Support and provide products in national projections. Provide better geometric quality products by using higher accuracy national DEM data for orthocorrection of Sentinel 2 compared to the ESA DTED1 90 m DEM. This is especially important north of 60 deg N where the DEM used by ESA is built on 1: scale Russian maps. Provide Level 2 processed data using e.g. the Sentinel Toolboxes. Produce enhanced cloud and cloud shadow mask. Prepare and provide data adapted for time series analysis. Produce user adapted subsets products for visual interpretation and GIS backdrop imagery. Provide data to local users through WMS and WCS. Offer storage and preprocessing of optical satellite data from additional satellite data such as Landsat 8 and others. The national Mirror Sites within the Collaborative Ground Segment will have access to the ESA Core rolling archive for bulk download of all requested and available data products. In theory the full global coverage of all Sentinel 1, 2 and 3 data could be downloaded while a realistic scenario in the case of the Swedish CGSS would be to define a specific geographic area of interest and a preselected list of standard products. 6.5 Sentinel Toolboxes There are free open source mission specific software toolboxes made available by ESA for the scientific exploitation of the Sentinel missions. These toolboxes contain tools for reading and reformatting data as well as L1 and L2 preprocessing tools and can be run interactively as general image processing tools or 16 MET CGSS MS v1.1

17 as plug in tools in the CGSS Mirror Hub. The toolboxes can also be used directly by users who wants to perform their own preprocessing and will also also widely used for training next generation scientists to the scientific exploitation of Sentinel data and multi mission data. ESA describe these Toolboxes as follows: Sentinel 1 Toolbox The Sentinel 1 Toolbox (S1TBX) consists of a collection of processing tools, data product readers and writers and a display and analysis application to support the large archive of data from ESA SAR missions including Sentinel 1, ERS 1 & 2 and Envisat, as well as third party SAR data from ALOS PALSAR, TerraSAR X, COSMO SkyMed and RADARSAT 2. The various processing tools could be run independently from the command line and also integrated within the graphical user interface. The Toolbox includes tools for calibration, speckle filtering, coregistration, orthorectification, mosaicking, data conversion, polarimetry and interferometry. The Sentinel 1 Toolbox is being developed for ESA by Array in partnership with DLR, Brockmann Consult and OceanDataLab Sentinel 2 Toolbox The Sentinel 2 Toolbox consists of a rich set of visualisation, analysis and processing tools for the exploitation of MSI data from the upcoming Sentinel 2 mission. As a multi mission remote sensing toolbox, it also supports the ESA missions Envisat (MERIS & AATSR), ERS (ATSR), as well as third party data from RapidEye, SPOT, MODIS (Aqua and Terra), Landsat (TM), ALOS (AVNIR & PRISM) and others. The various tools can be run from an intuitive desktop application or via a command line interface. A rich application programming interface allows for development of plugins using Java or Python. The Sentinel 2 Toolbox is being developed for ESA by CS in partnership with Brockmann Consult, CS Romania, Telespazio Vega Deutschland, INRA and UCL. The first release of the Sentinel 2 Toolbox is a stand alone toolbox intended for exploitation of high resolution optical data. It provides all tools known from the ESA BEAM toolboxes, plus a Sentinel 2 product reader, a SPOT 1 to 5 product reader, and a RapidEye product reader Sentinel 3 Toolbox The Sentinel 3 Toolbox consists of a rich set of visualisation, analysis and processing tools for the exploitation of OLCI and SLSTR data from the upcoming Sentinel 3 mission. As a multi mission remote sensing toolbox, it also supports the ESA missions Envisat (MERIS & AATSR), ERS (ATSR), SMOS as well as third party data from MODIS (Aqua and Terra), Landsat (TM), ALOS (AVNIR & PRISM) and others. The various tools can be run from an intuitive desktop application or via a command line interface. A rich application programming interface allows for development of plugins using Java or Python. The Sentinel 3 Toolbox is being developed for ESA by Brockmann Consult in partnership with the University of Reading, C S France, ACRI ST and Array. This first release of the Sentinel 3 Toolbox is a stand alone toolbox intended for exploitation of medium resolution optical and SMOS data. It provides all tools known from the ESA BEAM and SMOS toolboxes, plus a Sentinel 3 data reader, an uncertainty data visualisation tool and a context search feature. 17 MET CGSS MS v1.1

18 7 Current Use of Satellite Data As previously described, the Saccess national satellite data archive has been an important factor for the operational use of HR optical satellite data in Sweden.This has been the case not only for large scale nationwide mapping and monitoring purposes but also for a large number of small scale use and downloading of satellite imagery by hundreds or even some thousands of users. The operational use of SAR data is mainly found in applications which requires all weather NRT data, e.g. for ice monitoring and maritime surveillance. Low resolution optical data from sensors like Envisat MERIS, Aqua and Terra MODIS and Spot VEGETATION are used in marine and meteorological applications. 7.1 Current Use of Optical HR Data Sentinel 2 Type Data As described in Section 4.3, the current use of satellite data for operational purposes in Sweden are mainly applications heavily reliant on the data provided by Saccess. In fact, the availability of yearly nationwide freely available data from Saccess has led to a widespread use of HR optical satellite data for different purposes. The largest operational users of the nationwide coverages from Saccess are the Swedish Forest Agency for its yearly monitoring of clear felled areas, the Environmental Protection Agency using the data for the mapping of protected areas (KNAS) produced by Metria and SLU using the datasets for the KNN forest parameter estimates. In addition to these applications, the Saccess data users can be found among forest companies mainly using the images as visual interpretation background data for GIS data. We also find many smaller users of Saccess data among forest services consultants, universities and students. There is an immediate increase in downloads of data when new remote sensing courses are staring at the universities. Most of those users are only downloading limited amounts of data over small geographic areas. The experiences from the yearly work of assembling and preparing the Saccess data and the problems of getting a single early cloud free coverage of HR data over Sweden and other high latitude cloudy regions, together with the complexity of manually selecting suitable datasets and the manual work of mosaicking data and masking out clouds and cloud shadows have been an inspiration for ESA when defining the characteristics of Sentinel 2. The high revisit frequency and spectral characteristics of Sentinel 2 will be the key for a more operational and automated preparation of data. Beside Saccess, other European wide HR satellite data coverages are also processed and analysed for the European Land Cover projects within the Copernicus Initial Operations services. The Corine Land Cover (CLC2012) is now produced by Lantmäteriet and the GIOLand High Resolution Layers for forest and imperviousness over Sweden, Norway, Finland, Iceland and the Baltic states are currently produced by Metria and partners for EEA. The data for these projects are supplied by ESA through the Data Warehouse but have also experienced the same type of difficulties of obtaining full cloud free large area coverages within the vegetation season over northern Europe. 7.2 Current Use of SAR Data Sentinel 1 Type Data Satellite SAR data are currently not used for large area mapping applications on land in Sweden. This in spite of the all weather capability of radar data. Some reasons for this are maybe the fact that SAR data are expensive when used for large area coverages and that users are inexperienced in interpreting the SAR data. This normally calls for more advanced techniques which currently more or less are only used within Swedish Remote Sensing research and development groups. There are also examples of local applications of SAR data in Sweden (e.g. interferometric measurements 18 MET CGSS MS v1.1

19 of land movement), although most of the currently operational applications of SAR satellite data are found in the field of Near Real Time applications. Examples of this are the operational sea ice monitoring and services to the icebreakers which is performed in cooperation between Swedish Agencies (SMHI, Swedish Maritime Administration, Swedish Coast Guard) and Finnish organisations. Data is provided by FMI from the Finnish direct receiving station in Sodankylä. Other use of SAR data is connected to emergency situations where data is required very fast and all weather capability is needed. MSB the Swedish Civil Contingencies Agency can receive data and rush mode mapping results through Copernicus Services and the International Charter on Space and Major Disasters. Examples of such emergency situations in Sweden are storm felled forest, large forest fires, flooding, landslides, and oil spills at sea. Other types of situations when sending personnel on missions abroad are earthquakes, tsunamis, etc. The data needs and data requirements of the Swedish Defence is similar to this. 7.3 Current Use of Optical LR Data Sentinel 3 Type Data Low resolutions optical data from sensors like Envisat MERIS, Aqua and Terra MODIS and Spot VEGETATION are used in operational water quality and algae bloom monitoring by SMHI and other organisations. MERIS and MODIS also provide a long list of products for maritime and atmospheric parameters as well as global fire mapping services. This kind of data is used operationally within the context of EUMETSAT and national weather services. Swedish researchers are also actively using MERIS and MODIS as well as historical AVHRR from polar orbiting meteorological satellites for temporal vegetation studies on regional and global scales. The time series methodologies developed for this purpose will also be of importance for the operational use of Sentinel 2 imagery as these high resolution data will have a high revisit frequency. 8 Swedish User Needs and Requirements An ad hoc survey of user needs and requirements on Sentinel data was made starting from our long experience of international and Swedish operational use, research and development in the field of satellite data applications. Telephone interviews were done with representatives from governmental agencies, research organisations in the field of remote sensing applications, forest companies and consulting companies. This was the way forward after realising that it would be a far too complex and time consuming task of understanding all the details and features of the Sentinel Core Ground segment and the characteristics of the products and the terms and conditions of data access for all types of users, before sending out a condensed technical description together with a questionnaire to a list of known potential Sentinel data users so that a compilation of user needs and requirements could be made. One reason for this is the fact that there is still an evolving process where some of the specifications are not completely fixed. The system is still under development and with some of the missing functions identified, such as the access to the long term archive for all users, the final functionality of the Core ground segment is difficult to describe. The ambition has not been to provide a complete and detailed list of firm commitments of requirements on products, coverage areas and amounts of data, but rather an input for categorising and grouping user requirements to a level sufficient for preliminary definition and dimensioning of alternative solutions for a Swedish CGSS. The questions considered in the user interviews have been: What satellite data are requested by the users What product types and processing levels are required and what is feasible to provide. What products adaptations are requested by Swedish users. Which geographic area of interest should be covered systematically. Requirements on delivery times Estimated amounts of data 19 MET CGSS MS v1.1

20 Other types of services requested Other consideration 8.2 User Categories When analysing statistics of users of Saccess data we find that the largest users of Saccess data are in the following categories: Large forest companies Swedish Forest Agency Swedish Environmental Protection Agency through consultants (Metria and others) Forest owners Consulting companies in forestry and environment GIS consultants Environmental organisations Students of GIS and Remote Sensing Research groups Private persons We should note that the new satellite data in Saccess acquired during the period June September are normally not available for download before October the same year, which makes the data set of less interest for monitoring purposes than a Sentinel CGSS could be. The bottlenecks in the Saccess set up is that because the SPOT data is purchased commercially from the data provider Airbus Defence and Space (previously SpotImage) must first be manually selected and accepted for purchase, then preprocessed and manually cloud masked for mosaicking. This can be performed continuously during the summer but the final data gaps cannot be filled until the end of the vegetation season when a complete overview of usable data from SPOT, IRS and Landsat is available. The systematic CGSS archive continuously filled with new data within 3 24 hours after data acquisition would with high probability attract a large amount of new types of users and open up new application fields where imagery from specific dates or fast access to data are key issues. The step from mapping using one yearly image data set and change detection between yearly dataset into monitoring which is based on a continuous flow of data will also open up completely new applications and increase the amount of data used compared to Saccess. The user interviews have revealed additional user categorisation dimensions when it comes to user interest and requirements of Sentinel data. These dimensions are: Sentinel mission S1, S2 or S3; this can also be explained as an interest for a specific data/sensor type. Geographical area of interest ( Sweden land and coastal waters, Baltic Sea, Baltic Sea basin) Delivery time after acquisition; NRT data vs standard delivery times. Product preprocessing levels. Amounts of data Remote Sensing experts vs non experts (user adapted and simplified products) User organisation type (scientific, consulting company, value added industry,.. ) R&D users vs operational users (lower level products for advanced processing for R&D; Application oriented user organisations interested in mapping results and images rather than satellite data for analysis. (Images and WMS services for visual backdrop in GIS or viewing services in web browsers) 20 MET CGSS MS v1.1

21 8.3 Generalised Swedish Users Needs and Requirements of Sentinel Data Geographic Areas of Interest The geographic area to cover by the CGSS can be defined stepwise for each Sentinel mission and product type. The different levels of coverage areas to consider are: Sweden land, lakes and coastal waters [ appr km²] The Baltic Sea and the Sea waters west of Sweden. [ appr km²] The Baltic Sea Basin [appr. 2 Million km² incl. Sweden ] The Arctics Local areas of interest globally (projects,cooperation activities). Some of these can be specified in advance, other areas can not be specified in advance and will require access to archived data Delivery time requirements Most land applications such as mapping and monitoring environment, forestry and agriculture are aimed at slowly changing targets will not require fast delivery NRT data other than emergency needs such as forest fires, flooding, storm damages and surveillance imagery for the Defense. The 3 hours which is the indicated delivery time from ESA for priority areas, which informally would mean Europe and the 24 hours guaranteed for global data will suffice. When it comes to marine and meteorological applications, NRT data are required in most cases. Examples of this are Sentinel 1 SAR data for sea ice mapping and ice breaker services, algae bloom monitoring in the Baltic Sea using Sentinel 3 data and the use of most Sentinel 3 products handled by EUMETSAT for marine and meteorological use. NRT data cannot be handled through the ESA Core Ground segment other than for the Copernicus Services (e.g. EMSA, My Ocean, Emergency..) from which e.g. MSB and SMHI will get some of these data Product preprocessing levels The product lists and preprocessing levels are very different between the three Sentinel missions. Sentinel 2 When it comes to Sentinel 2 data, the situation is quite straight forward. Most users require data over Sweden in Swedish projections and with a geometric quality which calls for the use of a national DEM for L1C production. For other parts of the area of interest north of 60 deg N, the same requirements apply. This implies that S2 L1B data is required as the starting point for further geometric processing into L1C ortho corrected data in national projections. For other parts of the world, most users will have to rely on the L1C data as produced by ESA. The alternative for the user to start with L1B data and using the Sentinel2 Toolbox together with a higher quality DEM for the processing into L1C ortho corrected data. If any other projection is required without using another DEM, the CGSS should be able to reproject the L1C data into another requested projection. Sentinel 1 NRT data, for which the standard products coming from the producing entity should be put into use at once in order to not lose any time for further processing. For these there is normally no requests for additional preprocessing or geometric reprojection of the data, as most NRT applications are marine. On the other hand, when considering SAR mapping applications on land, the requirements for applying a Swedish DEM and producing data in national projections are similar to the Sentinel 2 case. This means that the requirements are to start with Level 1 SLC for the processing into Level 1 Ground Range data. An additional issue for SAR data is the fact that parallaxes or local geometric displacements due to topography are much more severe in SAR data than on optical data. The topographic radiometric correction also calls for high accuracy DEM. Level 1 Ground Range products could then be produced in the CGSS using the same DEM as for Sentinel 2 or by advanced users by using the Sentinel 1 Toolbox for this purpose. 21 MET CGSS MS v1.1

22 Sentinel 3 The list of Sentinel 3 data is long and complex but because this the sensors are Low Resolution sensors there are no geometric quality requirements in additional to the data produced by ESA or through a NRT data provider. This would mean that the CGSS task for Sentinel 3 would be to archive and distribute copies of ESA products Summary of User Needs of Sentinel Product Types We have tried to organise examples on applications and users for each type of product in the list of ESA standard products for each Sentinel mission in Table 6. Product type Applications (examples) Potential users (example) Sentinel 1 L1 SLC (slant range geometry) Sentinel 1 L1 GRD (ground range) Archive, Interferometric applications, ground movements, land cover. starting point for higher level products Sea ice, shipping, oil spill, storm fellings... R&D (Chalmers, FOI, Deantus, SLU, Metria) LKAB, Trafikverket (Sw Transport Admin) MSB, Sjöfartsverket Kustbevakningen (Sw Coast Guard), SMHI Sentinel 1 L2 Ocean Marine applications SMHI, HaV. Sentinel 2 L1B (sensor geometry) Sentinel 2 L1C (sensor geometry) Archive, starting point for higher level products Basic product for most applications, Land cover, forestry, agriculture, urban mapping, change detection (clear felled areas, land use change), environmental monitoring (forest damages, fire scars, long term changes), image backdrops in GIS, image map services Starting point for L2 products (atmospheric corrected, biophysical parameters) CGSS, R&D, Skogsstyrelsen (Sw Forest Agency) Naturvårdsverket (SEPA) Forest Companies Jordbruksverket (Sw Board of Agriculture) Lantmäteriet (National Land Survey) SLU, SkogForsk, Lund University, other research organisations Metria, Brockmann, other RS/GIS companies WWF, Naturskyddsföreningen (SSNC) and others, Google, Eniro, Hitta, general public. Sentinel 2 L2 (BOA) [produced by CGSS] Sentinel 3 OLCI Level 1B SLSTR Level1B Sentinel 3 OLCI L2 Land (ESA product Required for all time series based services, automatic change monitoring, Land vegetation monitoring (global), Marine water quality Water temperature Global and regional vegetation dynamics and change All organisations interested in change monitoring, R&D using Toolbox R&D, Brockmann, HaV SMHI (?) R&D Sentinel 3 OLCI L2 Water Marine water quality, algae blooms Brockmann, SMHI, SEPA, HaV Sentinel 3 EUMETSAT products Marine applications, atmosphere, meteorology, SMHI, HaV, R&D, Coast Guard (?) Table 6: Summary of user needs of Sentinel product types On top of this there is a general request from more operational users to supply data through viewing 22 MET CGSS MS v1.1

23 services in web browsers and as WMS services to feed GIS systems with backdrop image data for visual interpretation work or as WCS services for analysis. For similar purposes and in order to simplify the use of images by less sophisticated users, there is also a need for repackaged and reformatted data in the form of 3 band rgb imagery supplied in more user friendly general accepted formats such as GeoTIFF and others. Higher level products such as an automatic cloud and cloud shadow masking is also regarded as a key issue for implementation of automatic tools for time series based change detection and monitoring applications. Product packaging in formats adapted for time series analysis and composites (10 day, 14 day or 4 weeks) for temporal vegetation studies are also requested Amounts of data to archive There are several users that require large amounts of data over Sweden. To have the full potential use of the data from all Sentinel Missions, the basic conclusion is that there is a general request to download and archive all Sentinel 2 and Sentinel 3 data over the geographic area of interest, at least covering the Swedish land and coastal area. By archiving and processing all data, this will open the possibility of having operational monitoring applications implemented based on time series methods. It will also finally reduce the big problems of the current generation HR satellites to provide cloud free data, not only once per year over Sweden at the best, but also enable users to get image data from more optimal dates of the year suited for different applications. In the case of Sentinel 1 the requirements of archiving all data are not so clear, partly because the SAr is an all weather sensor and that the monitoring applications mainly require NRT data which would optimally not pass through the CGSS before reaching the end user in order not to slow down the delivery of the data. Some users say that maybe a few complete coverages of Sweden per year would be enough as a basis for SAR change detection in emergency situations such as flooding, storm felled forest or land slides. Table 7 summarises the coverages and amount of data estimated to be needed by different representative users. Type of use data requirements Potential users (example) Sweden recurrent rolling coverage (S1 selective archive; S2 all; S3 all) Baltic Sea Basin (S1 selective archive; S2 all; S3 all) Swedish Emergency 24 h (S2, S1, S3) Skogsstyrelsen (Sw Forest Agency) Naturvårdsverket (SEPA) Forest Companies Jordbruksverket (Sw Board of Agriculture) Lantmäteriet (National Land Survey) SLU, SkogForsk, Lund University, other research organisations Metria, Brockmann,other RS and GIS companies WWF, Naturskyddsföreningen (SSNC) and others SMHI, HaV (SWaM) Naturvårdsverket (SEPA) research organisations, WWF, Naturskyddsföreningen (SSNC) and others MSB,Kustbevakningen (Sw Coast Guard), SMHI. S1 och S3: Fast delivery data; NRT 30 min 3 h e.g.. sea ice, shipping, oil spill, wind, waves, fires... Global area of interest (S1, S2, S3) SMHI Sjöfartsverket (Sw Maritime Administration) Kustbevakningen (Sw Coast Guard) MSB, Swedish Defense, SMHI Consulting companies, WWF, NGOs, SIDA, research organisations Table 7: Summary of user needs of data 23 MET CGSS MS v1.1

24 8.3.5 Future Saccess Data Availability The availability of Sentinel 2 data will potentially open up new application and make the use of up to date imagery much simpler than today. Future change detection and monitoring applications will probably use Sentinel 2 and Landsat 8 in combinations. There are several international examples of initiatives for developing advanced methods for combining Landsat 8 and Sentinel 2 data for time series analysis. Figure 3 shows the example of a flow chart for the NASA / Univ of Maryland implementation for that purpose. Figure 3:_NASA / Univ of Maryland Landsat Sentinel 2 fusion method Using the archived data from Saccess together with the Sentinel 2 data will also be an important way for mapping of changes using long historical series of images. Therefore it will be of importance for many users that the availability of Saccess data is secured for future access. This could be accomplished either by continued operations of the current Saccess system or by transferring the Saccess data into the CGSS environment, which would technically be a simple task, especially as the amount of data in Saccess is only appr. 1 TB. When it comes to the future of the continued yearly HR data coverage over Sweden within Saccess an obvious conclusion might be that there is no need for such parallel work as the sensors available for this would be either Sentinel 2 available though CGSS or Landsat 8, which potentially also should be included in the CGSS environment. Other historical data of use for the same purpose are the now available historical Landsat data archives freely available from ESA and from USGS. 24 MET CGSS MS v1.1

25 8.6 Implementation Scenario CGSS Potential Functional Blocks in a Swedish CGSS Figure 3 shows a concept of functional building blocks of CGSS with optional application oriented monitoring services, which could be functionally connected to CGSS. AT the same time the figure represents a potential timeline for the implementation and development of CGSS starting from the bottom. Figure 4: Functional building block for different CGSS product levels Recommendations for Implementation Steps in Preparation for a Swedish CGSS The Swedish CGSS Mirror should at a minimum be able to perform the following functions: automatic downloads of all new data according to predefined criteria, preparation and processing of metadata for cataloging and archiving of all downloaded products, support browsing and searching for data by users, provide an interface for formatting and delivering copies of downloaded standard products to Swedish users. The functionality of the CGSS should from a user perspective be implemented in several functional stages which should be ranked in priority based on whether the function is a basic critical function and decided serving many users but also from a priority of user requirements vs each other. The first basic tasks required to be put in place soon in order to be operational for downloading and archiving of the already available Sentinel 1 data from the ESA Core Ground Segment are: 25 MET CGSS MS v1.1