Customer: ESA Document Ref.: S3MPC.ACR.HBK.003 Contract No.: 4000111836/14/I-LG Date: 28/04/2021 Issue: 1.1
PREPARATION AND OPERATIONS OF THE MISSION PERFORMANCE CENTRE (MPC) Project: FOR THE COPERNICUS SENTINEL-3 MISSION Title: Copernicus Sentinel-3 SYN Land User Handbook Author(s): C. Hénocq, J. Bruniquel (ACRI-ST), S. Dransfeld (ESA) Filename Sentinel3-SYN-Land-Handbook - i1r1 - 28Apr2021.docx
Disclaimer The work performed in the frame of this contract is carried out with funding by the European Union. The views expressed herein can in no way be taken to reflect the official opinion of either the European Union or the European Space Agency.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: ii
Changes Log
Version Date Changes 1.0 15/02/2021 First version 1.1 28/04/2021 New sections about SYN AOD product
List of Changes
Version Section Changes 1.1 5.2.3 New section about SYN-AOD
7.1 Preliminary validation results about SYN-AOD are added
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: iii
Table of content
1 Introduction ...... 1 2 SYN Quick Start ...... 2 3 General information...... 4 3.1 The Copernicus Programme ...... 4 3.2 The European Space Agency ...... 4 3.3 The Sentinel-3 mission ...... 5 3.4 The SYN « instrument » ...... 6 4 SYN acquisitions ...... 7 4.1 Coverage ...... 7 4.2 Measurement principles ...... 7 4.3 Validation ...... 7 5 SYN Algorithms and Processing levels ...... 8 5.1 Level 1 ...... 8 5.2 Level 2 ...... 10 5.2.1 SYN Level 2 SDR and VGT-P like ...... 10 5.2.2 SYN-VGT-S composite ...... 11 5.2.3 SYN-AOD ...... 12 6 SYN products ...... 14 6.1 File types ...... 14 6.2 Timeliness ...... 14 6.3 Data format ...... 14 6.4 PDUs ...... 16 6.5 Naming Convention ...... 17 6.6 Level 2 product content ...... 19 7 Data Quality Information ...... 25 7.1 Quality Assessment of SYNERGY products ...... 25 7.2 Known limitations of SYNERGY Products ...... 29 8 Helpdesk ...... 30 8.1 Access and use of SYN products ...... 30 8.1.1 How to get access to SYN products? ...... 30 8.1.2 How to read and display the SYN products? ...... 30 8.2 FAQ ...... 30 8.3 If you have a question ...... 33 8.4 Useful links ...... 34 8.4.1 About Copernicus ...... 34 8.4.2 About ESA and the SENTINELs missions ...... 34 8.4.3 About SYN ...... 34 8.4.4 About S3 toolbox ...... 34 8.5 Acronyms and abbreviations ...... 35 Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 1
1 Introduction
This Sentinel-3 SYN Land User Handbook aims at providing a summary of key information useful for any users interested in using these products in their applications.
After providing general information about the Copernicus programme, the role of the European Space Agency and the scope of the Sentinel-3 mission, it gives a focused information about the SYN products: the algorithms, the processing levels, the product contents and the format. A brief review of the Data Quality Information is also given.
Lastly, a Helpdesk section provides useful practical information, such as how to access the products, how to visualize them, or to extract some useful information. This section includes a FAQ chapter and a list of useful links to get more details about the SYN products.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 2
2 SYN Quick Start
SYNERGY products are created from a combination of OLCI and SLSTR Level-1B products (including both nadir and oblique views). The SYNERGY swath is then corresponding to the common area between OLCI and SLSTR swaths, restricted to the daylight part of the SENTINEL-3 orbit (i.e., where the sun zenith angle at satellite ground track is lower than 80°).
As a result, the swaths of SYNERGY L2 products, SY_2_SYN and SY_2_AOD products are similar to the OLCI ones ( ~1 270 km). The SLSTR nadir and oblique view areas not covered by OLCI images are filtered out from SYNERGY processing.
Concerning SYNERGY VGT-like products, the width of the swath is similar to the SYN L2 products, but the latitude range is restricted from 56°S to 75°N (to be consistent with VEGETATION-like products).
The products have a resolution of 300 m and SYN L2 products are mapped on the same regular grid than OLCI. VGT-like products are mapped on a Plate-Carrée grid of 1 km.
The mean global coverage revisit time is based on the longest revisit time of the two instruments, OLCI and SLSTR. It is less than 2 days at the equator with two operational satellites.
SY_2_SYN and all SYNERGY VGT-like products are land-only products, any sea pixels will be discarded from the processing. On a contrary, SY_2_AOD is a global product providing aerosol datasets over both ocean and land areas.
Products are supplied in NetCDF-4 format in 3 minute ‘granules’ (see Section6.4), except the SYN-AOD which are delivered by half-orbit.
These products can be downloaded from the ESA Copernicus Open Access Hub (https://scihub.copernicus.eu), either searching by observation time, or by area of the globe (see Section 8.1.1). The global revisit time at the equator is less than one day when combining both satellites (see Section 3.3). Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 3
Once products are downloaded, they can be read, displayed, and analysed using:
❖ The ESA SNAP toolbox (see Section 8.1.2)
❖ Other generic NetCDF tools, e.g., the NASA Panoply tool
❖ Standard Unix command, ncdump (ncdump -h to view the header only)
❖ Scripting languages, e.g., using the Python netCDF4 library
SYN Level 2 SDR and VGT-P like
❖ The SY_2_SYN products provide Surface directional reflectance for all contributing SLSTR and OLCI channels and Aerosol Optical Thickness at a 300m resolution.
❖ The SY_2_VGP products provide TOA reflectance for all VGT channels on the 1 km Plate Carrée grid.
SYN-VGT-S composite
❖ Daily and 10-day composite products which are consistent with 1km SPOT-VEGETATION-like products (VGT-S1 or VGT-S10) and based on the “maximum NDVI” selection.
SYN-AOD
❖ Aerosol products at a resolution of 4.5 km based on OLCI and SLSTR inputs.
❖ Global product over land and sea areas, delivered in NTC timeliness. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 4
3 General information
3.1 The Copernicus Programme
Copernicus has been specifically designed to meet user requirements for environmental monitoring purposes. Based on satellite and in situ observations, the Copernicus services deliver near-real-time data on a global level which can also be used for local and regional needs, to help us better understand our planet and sustainably manage the environment we live in.
Copernicus is served by a set of dedicated satellites (the SENTINEL families) and contributing missions (existing commercial and public satellites). The SENTINEL satellites are specifically designed to meet the needs of the Copernicus services and their users. Since the launch of SENTINEL-1A in 2014, the European Union set in motion a process to place a constellation of almost 20 more satellites in orbit before 2030.
Copernicus also collects information from in situ systems such as ground stations, which deliver data acquired by a multitude of sensors on the ground, at sea or in the air.
There are six Copernicus services whose aim is to transform the satellite and in situ data into value- added information by processing and analysing the data. These services are atmosphere, marine, land, climate change, security, emergency. The information provided by the Copernicus services can be used by end users for a wide range of applications in a variety of areas. The main users of Copernicus services are policymakers and public authorities who need the information to develop environmental legislation and policies or to take critical decisions in the event of an emergency, such as a natural disaster or a humanitarian crisis.
The Copernicus programme is coordinated and managed by the European Commission. The development of the observation infrastructure is performed under the aegis of the European Space Agency for the space component and of the European Environment Agency and the Member States for the in-situ component.
3.2 The European Space Agency
The European Space Agency (ESA) is dedicated to the peaceful exploration and use of space for the benefit of everyone. Established in 1975, ESA is an international organisation with 22 Member States and, for more than 40 years, has promoted European scientific and industrial interests in space. By coordinating the financial and intellectual resources of its members, it can undertake programmes and activities far beyond the scope of any single European country.
ESA's programmes are designed to find out more about Earth, its immediate space environment, our Solar System and the Universe, as well as to develop satellite-based technologies and services, and to promote European industries. ESA also works closely with space organisations outside Europe.
ESA's purpose shall be to provide for, and to promote, for exclusively peaceful purposes, cooperation among European States in space research and technology and their space applications, with a view to their being used for scientific purposes and for operational space applications systems: Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 5
❖ by elaborating and implementing a long-term European space policy, by recommending space objectives to the Member States, and by concerting the policies of the Member States with respect to other national and international organisations and institutions;
❖ by elaborating and implementing activities and programmes in the space field;
❖ by coordinating the European space programme and national programmes, and by integrating the latter progressively and as completely as possible into the European space programme, in particular as regards the development of applications satellites;
❖ by elaborating and implementing the industrial policy appropriate to its programme and by recommending a coherent industrial policy to the Member States.
The ESA Member States are: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom. Slovenia and Latvia are Associate Members. Canada takes part in some projects under a cooperation agreement. Bulgaria, Croatia, Cyprus, Malta, Lithuania and Slovakia have cooperation agreements with ESA.
The budget of ESA for 2019 is €5.72 billion. ESA operates on the basis of geographical return, i.e. it invests in each Member State, through industrial contracts for space programmes, an amount more or less equivalent to each country’s contribution.
ESA is developing a new family of missions called SENTINELs specifically for the operational needs of the Copernicus programme. Each SENTINEL mission is based on a constellation of (at least) two satellites to fulfil revisit and coverage requirements, providing robust datasets for Copernicus Services. These missions carry a range of technologies, such as radar and multi-spectral imaging instruments for land, ocean and atmospheric monitoring.
Looking to the future, six high-priority candidate missions are being studied to address EU policy and gaps in Copernicus user needs, and to expand the current capabilities of the Copernicus space component: CHIME – Copernicus Hyperspectral Imaging Mission, CIMR – Copernicus Imaging Microwave Radiometer, CO2M – Copernicus Anthropogenic Carbon Dioxide Monitoring, CRISTAL – Copernicus Polar Ice and Snow Topography Altimeter, LSTM – Copernicus Land Surface Temperature Monitoring, ROSE-L – L-band Synthetic Aperture Radar.
3.3 The Sentinel-3 mission
The SENTINEL-3 mission is jointly operated by ESA and EUMETSAT to deliver operational ocean and land observation services. The main objective of the SENTINEL-3 mission is to measure sea surface topography, sea and land surface temperature, and ocean and land surface colour with high accuracy and reliability to support ocean forecasting systems, environmental monitoring and climate monitoring. The mission definition was driven by the need for continuity in provision of ERS, ENVISAT and SPOT vegetation data, with improvements in instrument performance and coverage.
SENTINEL-3A was launched on 16 February 2016 and SENTINEL-3B was launched on 25 April 2018.
The spacecraft carries four main instruments: Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 6
❖ OLCI: Ocean and Land Colour Instrument
❖ SLSTR: Sea and Land Surface Temperature Instrument
❖ SRAL: SAR Radar Altimeter
❖ MWR: Microwave Radiometer
❖ These are complemented by three instruments for Precise Orbit Determination (POD):
DORIS: a Doppler Orbit Radio positioning system
GNSS: a GPS receiver, providing precise orbit determination and tracking multiple satellites simultaneously
LRR: to accurately locate the satellite in orbit using a Laser Retro-Reflector system.
The SENTINEL-3 orbit is similar to the orbit of Envisat allowing continuation of the ERS/Envisat time series. It uses a high inclination orbit (98.65°) for optimal coverage of ice and snow parameters in high latitudes.
The SENTINEL-3 orbit is a near-polar, sun-synchronous orbit with a descending node equatorial crossing at 10:00 h Mean Local Solar time. In a sun-synchronous orbit, the surface is always illuminated at the same sun angle. The orbit reference altitude is 814.5 km.
The orbital cycle is 27 days (14+7/27 orbits per day, 385 orbits per cycle). The orbit cycle is the time taken for the satellite to pass over the same geographical point on the ground.
The two in-orbit SENTINEL-3 satellites enable a short revisit time of less than two days for OLCI and less than one day for SLSTR at the equator based on the instruments’ respective swath widths.
SENTINEL-3B's orbit is identical to SENTINEL-3A's orbit but flies +/-140° out of phase with SENTINEL-3A.
3.4 The SYN « instrument »
Sentinel 3 SYNERGY is not strictly speaking an instrument but a combination of the OLCI and SLSTR L1b acquisitions with original objective to provide surface vegetation products similar to those obtained from the VEGETATION instrument on SPOT. This objective has then been extended to the continuity of PROBA-V products but also to the production of global aerosol products, providing over land and sea the aerosol optical thickness for different spectral range.
The first steps of SYNERGY processing chain is then to collocate and co-register OLCI and SLSTR simultaneous acquisitions, project these acquisitions on a reference grid and take benefit of this wider radiometric and angular range to apply an aerosol retrieval algorithm.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 7
4 SYN acquisitions
4.1 Coverage
SYNERGY products are created from a combination of OLCI and SLSTR Level-1B products (including both nadir and oblique views). The SYNERGY swath is then corresponding to the common area between OLCI and SLSTR swaths, restricted to the daylight part of the SENTINEL-3 orbit (i.e. where the sun zenith angle at satellite ground track is lower than 80°).
As consequences, the swaths of SYNERGY L2 products, SY_2_SYN and SY_2_AOD products, are similar to the OLCI ones ( ~1 270 km). The SLSTR nadir and oblique view areas not covered by OLCI images are filtered out from SYNERGY processing.
Concerning SYNERGY VGT-like products, the width of the swath is similar to the SYN L2 products but the latitude range is restricted from 56°S to 75°N (to be consistent with VEGETATION-like products).
The mean global coverage revisit time is based on the longest revisit time of the two instruments, OLCI and SLSTR. It is less than 2 days at the equator with two operational satellites.
4.2 Measurement principles
SYNERGY processing is taking benefit of the wider radiometric and angular range, offered by the combination of OLCI and SLSTR acquisitions, to perform an aerosol retrieval processing module. This combination is valid thanks to the simultaneity of OLCI and SLSTR acquisitions. The common reference band, at 865 nm, added to known inter-channel spatial misregistration allows the computation of co- registration and collocation grids between all OLCI and SLSTR spectral bands.
SYNERGY processing and products have also been designed to ensure the continuity of SPOT- VEGETATION datasets. Content of VGT products have been mimicked into SYN VGT-like products and specific algorithms defined to convert OLCI and SLSTR bands into VGT ones.
4.3 Validation
SYNERGY product validation is focusing on the quality of the co-registration process. As the radiometric information from OLCI/SLSTR Level-1B products is not changed by the SYNERGY Level 1 processing module, consistency checks with original Level-1B input are sufficient. It is also assumed that for geolocation, a geometric modelling is taken into account in Level-1B processing.
Concerning SYNERGY Level 2 datasets, atmospheric correction scheme validation is essential, ensured by comparison between AOD ground-based measurements and SYNERGY retrieved AOD. Inter-comparison between SYNERGY and MODIS are also performed regarding surface reflectance.
The SYN-VGT product has been also designed to ensure continuity with the SPOT VGT mission, therefore the validation also includes comparison with PROBA V products. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 8
5 SYN Algorithms and Processing levels
The SYNERGY processing chain is taking as inputs OLCI and SLSTR L1B products and provides both segment and composite products.
Figure 1: Global Architecture of operational SYNERGY processing chains
Several levels are distinguished in SYNERGY operational chains:
❖ SYN Level-1 module dedicated to the OLCI and SLSTR co-registration and projection onto a reference grid
❖ SYN L2/VGT-like module focusing on the aerosol retrieval process and the creation of VGT-P like products
❖ SYN VGT-S module dedicated to the computation of daily and decade synthesis of VGT-P like products, based on quality selection and on the maximum value of NDVI
❖ SYN global aerosol module creating a 4.5 km-resolution aerosol product over land and sea areas
5.1 Level 1
The SYNERGY Level 1 processing module aims to co-register OLCI and SLSTR L1B datasets and project them onto the same grid, i.e., the OLCI acquisition grid. This process requires to retrieve OLCI and SLSTR radiances and brightness temperature in their own acquisition geometry. The annotations data are also projected in their original acquisition grid. Thanks to this first step, all radiometric information is then available – orphans and removed pixel included – avoiding biases introduced by the regridding /spatial sampling process.
The computation of the correspondence and coregistration grids between OLCI and SLSTR is possible thanks to the common reference channel 865 nm and to the selection of ground-control points (called Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 9
GCPs). These GCPs could be regularly created over the whole image (then filtered out depending on their surface classification, cloud coverage, …) or derived from an external database.
Over these selected GCPs, radiometric images of SLSTR 865 nm band are extracted and compared to the OLCI 865 nm acquisitions. The OLCI image is moved around according to shift vectors and the cross- correlation with the fixed SLSTR window is calculated. The elements of the shift vectors at which a maximum in cross-correlation is reached determine the pixel deregistration between OLCI and SLSTR reference channel. In a second time, deregistration information for all pixels is obtained through several consecutive interpolations and fixed instrumental intra-misregistration between the different channels of the same instrument.
Each SLSTR and OLCI pixels can then be projected onto the same reference grid defined as the OLCI acquisition grid. Therefore, all OLCI and SLSTR L1B radiometric measurements as well as also contextual parameters like angular and spectral data, are available on the same grid of 300m. These datasets are kept internally and transferred to SYN Level 2 module resolution as inputs to an aerosol retrieval module.
Note that this process is only applied on relevant OLCI and SLSTR channels, i.e., non-absorbing channels and channels not dedicated to cloud detection. The 16 first SYNERGY channels are corresponding to the used OLCI channels (i.e., all OLCI channels except Oa13, Oa14, Oa15, Oa19 and Oa20). Then, SYNERGY channels 17 to 21 are related to the SLSTR used channels (S1, S2, S3, S5 and S6) acquired in nadir view, whereas SYN channels 22 to 26 are the same SLSTR channels but associated with oblique view.
Table 1: Radiometric resolution of SYNERGY dataset
SYNERGY Central Width Original SYNERGY Central Width Original channels Wavelength (nm) Instrument channels Wavelength (nm) Instrument (nm) Channel (nm) Channel
SYN01 400 15 Oa01 SYN14 865 20 Oa17
SYN02 412.5 10 Oa02 SYN15 885 10 Oa18
SYN03 442.5 10 Oa03 SYN16 1 020 40 Oa21
SYN04 490 10 Oa04 SYN17 555 20 S1 (nadir view)
SYN05 510 10 Oa05 SYN18 659 20 S2 (nadir view)
SYN06 560 10 Oa06 SYN19 865 20 S3 (nadir view)
SYN07 620 10 Oa07 SYN20 1 610 60 S5 (nadir view)
SYN08 665 10 Oa08 SYN21 2 250 50 S6(nadir view) Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 10
SYNERGY Central Width Original SYNERGY Central Width Original channels Wavelength (nm) Instrument channels Wavelength (nm) Instrument (nm) Channel (nm) Channel
SYN09 673.75 7.5 Oa09 SYN22 555 20 S1 (oblique view)
SYN10 681.25 7.5 Oa10 SYN23 659 20 S2 (oblique view)
SYN11 708.75 10 Oa11 SYN24 865 20 S3 (oblique view)
SYN12 753.75 7.5 Oa12 SYN25 1 610 60 S5 (oblique view)
SYN13 778.75 15 Oa16 SYN26 2 250 50 S6 (oblique view)
5.2 Level 2
The SYNERGY Level 2 includes 3 different processing chains, each of them taken into account the internal SYN L1 dataset as input.
5.2.1 SYN Level 2 SDR and VGT-P like
This processing chain is the more complex one as it aims to output three types of products:
❖ The SY_2_SYN products, available to users and providing Surface directional reflectance for all contributing SLSTR and OLCI channels and Aerosol Optical Thickness at a 300m resolution
❖ The SY_2_VGP products, available to users and providing TOA reflectance for all VGT channels on the 1 km Plate Carrée grid
❖ The SY_2_VGK products, not available to users and considered as input to the SYN VGT-S composite processing module.
All these products are land-only products, any sea pixels will be discarded from the processing.
The core algorithm of this SYN Level processing module is an aerosol retrieval based on an approach combining dark object and multiple view-angle methods derived from an existing work for MERIS and AATSR. For a given atmospheric aerosol model (i.e. continental aerosol model) and a parameterized Aerosol Optical Depth computed at 550 nm, a set of surface reflectances is derived from OLCI/SLSTR data. The derived Error metric is then minimized with regards to angular and spectral constraints, providing the realistic value of Aerosol Optical Thickness.
To minimize biases and errors, this aerosol retrieval process is performed over macro-pixels, defined in the OLCI instrument grid. All L1B parameters are averaged over 15 by 15 pixels but discarding all sea or Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 11
cloudy or invalid pixels. The aerosol retrieval module is then launched on macro-pixel including more than 50% of clear-sky land pixels.
If a macro-pixel includes less than 50% of clear-sky and pixels or if the aerosol retrieval process fails, AOD datasets will be completed either by interpolating the valid neighbouring AOD or using climatological data.
Once a retrieved AOD is associated with each macro-pixel, results are projected on the 300m grid and used as part of the atmospheric correction to obtain Surface Directional Reflectance dataset.
From this SDR dataset provided for all relevant OLCI and SLSTR channels, the VGT-like processing will compute a product as consistent as possible with VEGETATION like products. The first step is then to derive VGT channels from OLCI and SLSTR ones using hyperspectral interpolation (a hyperspectral surface reflectance spectrum is constructed from SYN L2 SDR); Hyperspectral upscaling (the hyperspectral surface reflectance is transported to TOA using retrieved SYN L2 AOD) and hyperspectral filtering (the hyperspectral TOA spectrum is weighted with the spectral response functions of the VGT bands, resulting in a set of simulated VGT TOA reflectances).
Table 2: Correspondence between SYNERGY and VGT channels
VGT Central Bandwidth Combined SYN Level 2 channels channel Wavelength (nm) (nm)
B0 450 20 SYN channel 2 and channel 3
B2 645 35 SYN channels 6 to 10
B3 835 55 SYN channels 13 to 16
MIR 1665 85 SYN channel 20 and channel 21
These datasets are projected on the 1 km Plate Carrée grid, using a stretched bicubic interpolation to maintain consistency with PROBA-V product. Status map flag are also constructed similarly to the ones included in PROBA-V, considering the weight of good-qualified and bad-qualified radiometry.
A final step is consisting with the computation of NDVI to ease the VGT-S compositing. NDVI is then only provided in internal VGK products and not in SYN L2 VGT-P products.
5.2.2 SYN-VGT-S composite
The objective of this module is to produce daily and 10-day composites consistent with 1km SPOT- VEGETATION-like product (VGT-S1 or VGT-S10).
The VGK products are provided by SYN L2 SDR and VGT-like module and include, on the 1 km Plate Carrée grid, the VGT surface reflectance and the associated NDVI. The daily composite is then generated Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 12
from all VGK products outputted the same day, whereas decadal products are composed from all daily SYN VG1-like products.
The composite is based on the same selection criteria than the PROBA-V products:
❖ first a selection regarding the quality of measurements, the cloud cover, the angles, … to reject non relevant pixels.
❖ Then, a selection based on the maximum NDVI value, in order to ensure coverage of all landmasses worldwide with a minimum extent of cloud cover.
❖ Surface reflectance and annotations of the VGK pixel corresponding to the maximum NVDI is copied into the daily and decadal product.
5.2.3 SYN-AOD This processing module is based on the same approach than the SYN L2 SDR but includes more complex features: Inversion procedure to retrieve continuous aerosol component mixture; uncertainty estimate per retrieval; inclusion of 4 aerosol components (dust, sea salt, fine mode strong absorbing, fine mode weak absorbing) …
However, the main difference with SYN L2 SDR is the inclusion of an oceanic model giving surface reflectance and uncertainty, dependent on wind speed, ocean colour, for SLSTR & OLCI wavebands and viewing geometry. The SYN AOD processing is then performed over land and sea pixels.
Another difference is the number of considered channels in the SYN AOD products: only one OLCI channel (440 nm) and the 5 solar SLSTR channels (i.e. except S4 dedicated to cloud detection).
Table 3: Radiometric resolution included in SYNERGY global aerosol dataset
SYN AOD Central Original Instrument Channel Wavelength (nm) Channel
SYN01 440 Oa03
SYN02 550 SLSTR S1
SYN03 670 SLSTR S2
SYN04 865 SLSTR S3
SYN05 1 600 SLSTR S5
SYN06 2 250 SLSTR S6
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 13
This module is starting from the internal SYN L1c dataset, gathering all OLCI and SLSTR L1b measurements on the same reference grid. The first step is also handling the resampling of 15*15 300m pixels obtaining a macro-pixel dataset of 4.5 km resolution. Same filtering concerning cloud and surface classification are applied: similarly, as for SYN L2 SDR, a macro-pixel is considered as land (respectively sea) and relevant for aerosol retrieval if more than 50% of the 15*15 pixels are classified as valid, clear- sky and land-pixels (respectively, valid, clear-sky and sea-pixels).
The aerosol retrieval module is based on a double optimization of the error model, using a-priori knowledge and Look-up-tables. However, this double optimization is no longer performed only on single continental module but using continuous aerosols components from 35 aerosols mixtures. The retrieved aerosol optical depth is no longer associated with a single aerosol model but with a combination of several models. Several others aerosol characteristics are then derived from the AOD: single scattering albedo associated with all SYN AOD channels, fine-mode aerosol optical depth at 550nm, aerosol Angstrom parameter between 550 and 865nm, dust aerosol optical depth at 550nm and aerosol absorption optical depth at 550nm.
An additional post-processing filtering is finally applied to detect missed cloudy pixels and based on a simple image processing considering all neighbours of a retrieved macro-pixel, i.e. boxes of 9 (3x3) macro-pixels. For an individual AOD retrieval to successfully pass this step of filtering the following criteria need to be met:
❖ at least 3 neighbouring macro-pixels with successful retrievals are required
❖ the sample corrected standard deviation of the valid macro-pixels in the 3x3 box needs to be smaller than the minimum of 0.15 or 80% of the mean AOD value + 0.04
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 14
6 SYN products
6.1 File types
Five SYNERGY product types are currently disseminated to users, all defined as Level 2 products, covering three different resolutions:
❖ SY_2_SYN providing mainly Surface Directional Reflectance for all SYN channels and aerosol parameters over Land on a 300m resolution.
❖ SY_2_VGP specified as a SPOT continuity product and providing TOA reflectances on the 1km Plate Carrée grid (i.e., defined from 180W to 180E and from 56S to 75N with a regular latitude- longitude sampling grid with 112 pixels per degree, leading to a resolution of 1 km at equator)
❖ SY_2_VG1 and SY_2_V10 also specified as SPOT continuity products providing maximum NDVI value composites received for 1 day and 10 days, on the 1 km Plate-Carrée grid
❖ SY_2_AOD: Global product over land and sea providing Aerosol optical thickness, surface reflectance and several aerosol characteristics on a wider resolution (4.5 km)
Table 4: SYNERGY Files types currently available to users
Product Description Availability Product type to the Level User
SY_2_SYN___ Surface Reflectance and Aerosol parameters over Land Available Level 2
SY_2_VGP___ 1 km VEGETATION-Like product (~VGT-P) - TOA Reflectance
SY_2_VG1___ 1 km VEGETATION-Like product (~VGT-S1) 1-day synthesis surface reflectance and NDVI
SY_2_V10___ 1 km VEGETATION-Like product (~VGT-S10) 10-day synthesis surface reflectance and NDVI
SY_2_AOD___ Global Aerosol parameter over land and sea on super pixel resolution (4.5 km x 4.5 km)
6.2 Timeliness
The SYNERGY Level 2 products are processed from consolidated OLCI and SLSTR L1b NTC products. They are then only provided in NTC (Non-Time critical) or STC (Short time critical) timeliness.
6.3 Data format
The SYNERGY data format follows the format defined for each SENTINEL-3 product in the PDGS product specification and is based on SENTINEL-SAFE. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 15
SENTINEL-SAFE is based on the XML Formatted Data Units (XFDU) developed by the Consultative Committee for Space Data Systems (CCSDS). SENTINEL-SAFE is a profile of XFDU, and it restricts the XFDU specifications for specific utilisation in the EO domain, providing semantics in the same domain to improve interoperability between ground segment facilities.
Each product package includes:
❖ a manifest file containing a metadata section and a data object section
❖ measurement data files
❖ annotation data files, if defined
netcdf files xfdumanifest.xml • Measurement data files • Annotation data files
.SEN3 product
Figure 2: SEN3 file format
All SYNERGY products are then providing several files:
❖ Manifest file (xfdumanifest.xml) describing the contents of the package
❖ Measurement data file providing radiometric dataset (Surface or TOA reflectance)
❖ Annotation data files providing contextual parameters such as geometry, geographical position, meteorological datasets and quality flags information.
These two last categories are stored in netCDF (version 4) format.
Only the SY_2_AOD product is gathering all measurement and annotation datasets in a single NetCDF file called NTC_AOD.nc
SENTINEL-3 user products are disseminated in Product Dissemination Units (PDU), in order to ease the online dissemination and data handling for the users. The PDU is a portion of data and is defined per product type.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 16
6.4 PDUs
The elementary unit of all SENTINEL-3 products released to the users is called PDU (Product Dissemination Unit) generated by the Product Unit Generator (PUG).
The direct output of the IPF is a so-called granule, which has a constant duration but not a constant positioning along the track. This non-constant positioning prevents from an easy comparison over time.
PDUs have a constant duration and they have a constant positioning along the track over time, as displayed in the next figures.
IPF granules – Cycle N IPF granules – Cycle N+1
Figure 3: IPF granules over two different cycles
PDUs – Cycle N PDUs – Cycle N+1
Figure 4: PDUs over two different cycles Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 17
It is important to note that the PUG does not modify the content of the products: there is no processing done on the physical content of data, the PUG being just a cutter/formatter of data, able to take M granules to make N PDUs.
SYNERGY SDR (SY_2_SYN) and VGT-P like (SY_2_VGP) products are provided as 3-minutes PDUs whereas SYNERGY global aerosol (SY_2_AOD) products are provided as a full daytime orbit (i.e. restricted to the daylight section of OLCI orbits).
The SYNERGY composite products (SY_2_VG1 and SY_2_V10) are provided per geographical area: Africa, North America, South America, Central America, North Asia , West Asia, South East Asia , Asian Islands, Australasia and Europe (white box).
Figure 5: Geographical windows considered in the definition of SYNERGY VGT-S like products
6.5 Naming Convention
The file naming convention for SYNERGY products is identified by the sequence of fields described here:
MMM_SY_L_TTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_YYYYMMDDTHHMMSS_[instance ID]_GGG_[class ID].SEN3 ❖ MMM is the mission ID:
S3A = SENTINEL-3A
S3B = SENTINEL-3B
S3_ = for both SENTINEL-3A and 3B ❖ SY is the data source/consumer (SY = SYNERGY) Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 18
❖ L is the processing level
"0" for Level-0
"1" for Level-1
"2" for Level-2
underscore "_" if processing level is not applicable. ❖ TTTTTT is the Data Type ID
Level-2 SYNERGY data: - "SYN___" = Surface reflectance and Aerosol Optical thickness at 300m resolution - "AOD___" = Surface reflectance and Aerosol Optical thickness at 4.5 km resolution
Level-2 SYNERGY VGT like data: - "VGT___" = TOA reflectance on the 1 km Plate Carrée grid - "VG1___" = 1 km – VEGETATION like daily composite surface reflectance and NDVI - "V10___" = 1 km – VEGETATION like decadal composite surface reflectance and NDVI ❖ yyyymmddThhmmss is the sensing start time
❖ YYYYMMDDTHHMMSS is the sensing stop time
❖ YYYYMMDDTHHMMSS is the product creation date
❖ [instance ID] The field consists of 17 characters, either uppercase letters or digits or underscores "_".
The instance id fields include, for instrument data products: - Duration,"_", cycle number, "_", relative orbit number,"_", FFFF "_" DDDD_CCC_LLL_FFFF_ - Frame along track coordinate “FFFF”= four digits; elapsed time in seconds from the ascending node indicating the frame start time. ❖ GGG identifies the centre which generated the file
❖ [class ID] identifies the class ID for instrument data products with conventional sequence "P_XX_NNN" where:
P indicates the platform (O for operational, F for reference, D for development, R for reprocessing)
XX indicates the timeliness of the processing workflow (NR for NRT, ST for STC, NT for NTC)
NNN indicates the baseline collection or data usage. ❖ .SEN3 is the filename extension.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 19
Example of filename:
❖ S3A_SY_2_SYN____20201101T001959_20201101T002259_20201101T100915_0179_064_287_ 3600_LN2_O_ST_002.SEN3
Acquired on the 1st of November 2020 between 00:19:59 and 00:22:59 UTC
Generated on the 1st of November 2020 at 10:09:15 UTC
Whose duration is 179 seconds
Acquired during cycle 064 and relative orbit 287
3600 seconds from the ascending node
Generated at LN2 centre, in STC timeliness
Whose baseline collection is 002.
6.6 Level 2 product content
The SY_2_SYN package includes 29 measurement data files and 9 annotation data files:
❖ The first 26 measurement files provide Surface Directional Reflectances (SDR) and their associated error estimates for all OLCI channels (except Oa13, Oa14, Oa15, Oa19 and Oa20) and SLSTR solar channels, nadir and oblique view (except S4 for nadir and oblique view). Aerosol optical thickness at 550 nm and aerosol Angstrom exponent are also provided in distinct files, projected on the image grid of the OLCI reference channel.
❖ The annotation files are providing
Angles and geographical information associated with OLCI and SLSTR tie—points
Geolocation information associated with SYN reference grid (similar to the OLCI L1b file)
Time of measurement for each line of the OLCI image grid
Geophysical atmospheric data, derived from the OLCI meteorological annotation file
Global quality flags derived from OLCI and SLSTR L1b products or related to SYN L2 processing
Synergy Aerosol Model Index Number data file (SYN_AMIN)
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 20
(a)
RGB OLCI image
(b) (c)
SYN L2 SDR_Oa17 SYN L2 AOT@550
Figure 6: S3A SYNERGY images over Italy acquired on 09th September 2020 between 09:35:40 and 09:38:40 UTC (see red rectangle on top-right panel) representing (b) surface reflectance associated with OLCI Oa17 channel (865 nm) and (c) retrieval Aerosol Optical thickness. The colour bar associated with these two images is provided in top-right panel and the cloud flag is represented in grey on image (b) and (c). panel (a) includes an RGB image created from an OLCI L1b product
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 21
The SY_2_VGP, SY_2_VG1 and SY_2_V10 packages are designed as SPOT continuity products, including respectively four and five measurement data files in addition to eight and nine annotation data files:
❖ The measurement data files are dedicated to TOA reflectance (in case of VGT-P like products) and Surface Reflectance (in case of VGT-S like products). These reflectances are provided for each defined VGT spectral band, i.e., B0, B2, B3 and MIR. The reflectances are indexed by number of columns, line by latitude and longitude dimension. Their geographical positions are also included in the measurement files.
❖ A fifth measurement file is added to VG1 and V10 products providing NDVI datasets.
❖ The annotation data files provide – on a sub-sampled resolution concerning VGT-P like products and on the same resolution concerning VGT-S like products – solar/ viewing azimuth and zenith angle, aerosol optical thickness at 550 nm, total column ozone, water vapour and the status flags. Synthesis time data is also provided only in VG1 and V10 products.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 22
(a)
SYN L2 V10 NDVI dataset over Europe
(b)
SYN L2 V10 NDVI over Africa
Figure 7: S3A SYNERGY decadal composite corresponding to the time frame 11/09/2020 – 20/09/2020 and representing NDVI dataset over (a) Europe and (b) Africa. Color bar is displayed in the bottom panel. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 23
The SY_2_AOD product is a global aerosol product, including only one measurement file, common to ocean and land area. All aerosol optical thickness and surface reflectance for 6 different radiometric bands is gathered in this single file, along with other aerosol characteristics like dust fraction, single scattering albedo. The description and position of macro-pixels are also included through geographical position of each corner and position of their centre.
Note that one important difference between SY_2_AOD and SY_2_SYN products is the lack of cosmetic filling in SY_2_AOD dataset. If the aerosol retrieval is not successful over one macro-pixel, there will be no_data in SY_2_AOD products. Thus, missing data are more frequent in SY_2_AOD products.
Location of S3B_SY_2_AOD orbit
Colorbar associated with AOD@865 nm
Image of the full SY_2_AOD orbit with cloud coverage in grey, and land classification in green
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 24
(a)
SYN L2 AOD@865 nm – zoom over South America. (b) Some fires are visible in Amazonia forest at the center of the image and on top of the image close to the SYN L2 AOD@865 nm – zoom over Atlantic Ocean – coastline the black area on the botton-right side is corresponding to a glint area
Figure 8: S3B SYNERGY global aerosol acquired on 30/07/2020 between 13:06:59 and 13:51:16 and representing AOD_865 dataset over (a) South America and (b)Atlantic Ocean. Colour bar is displayed in the top-right panel.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 25
7 Data Quality Information
7.1 Quality Assessment of SYNERGY products
Quality assessment of SYN L2 products are derived from comparative analysis performed by the S3MPC and using either ground-based measurement (AERONET stations) or satellite products (MODIS or PROBA-V). These analyses are focusing on SYN L2 Aerosol Optical thickness, SYN L2 surface reflectance and VGT surface reflectance.
Note that at present (2020) the SYN AOD products are still under-going a validation phase, only preliminary results will be provided in this document.
Quality Assessment of SYN L2 Aerosol Optical Thickness:
Comparisons with ground-based measurement of AOD from AERONET stations show a global overestimation of the SYN L2 retrieved AOD on both S3A and S3B. The matchups between SYNERGY and AERONET data have been created as followed:
❖ The maximum time difference between AERONET measurements and satellite acquisition should be one hour.
❖ Only clear sky and successful satellite data are taken into account. Satellite AOD is averaged over a 5*5 macro-pixel centred on the AERONET stations.
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 26
Figure 9:AOD (550nm) matchups between SYNERGY processor data and AERONET in-situ measurements for (a) S3A and (b) S3B. (c) Black dots indicate the stations geolocation
S3MPC experts are working on the cause and possible correction of this over-estimation. One lead is the use of a single continental aerosol model and a non-flexible algorithm with respect to the selection of aerosol models. This suggestion is emphasized by the preliminary results obtained with SYN AOD products showing better agreement with in-situ data.
Figure 10: AOD (550nm) matchups between SYNERGY data and AERONET in-situ measurements for (a) S3A SYN SDR and (c) S3B SYN SDR and, over the same stations, matchups with (b) S3A SYN AOD and (d) S3B SYN SDR. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 27
Quality Assessment of SYN L2 Surface Reflectance:
Comparisons with MODIS Surface reflectance have also been conducted to estimate the quality of SYN SDR datasets. The inter-comparison is performed over 8 different scenes, representing different biomes and surfaces, and for a single day for each scene.
For each scene, the 14th SYNERGY band (corresponding to Oa17 band – OLCI, 865 ± 20nm) and b2 MODIS band (860 ± 20nm) are taken into account. The 500m nadir normalised SDR data in the MCD43A4 (NBAR) MODIS products is considered. The BDRF model used in MCD43A4 products for the normalisation of the surface reflectance is based on the Ross-Li polynomial albedo representation.
As the acquisition geometry of MODIS and SYNERGY are not the same, a normalization of SYNERGY datasets is required through a correction of the BRDF model and to the projection of SYNERGY data into the MODIS reference grid.
Results show a good agreement globally with low dispersion, except over desert sites:
Figure 11: Inter-comparison between normalised SYN SDR (Oa17) products and normalised SDR MODIS (b2) products over the 8 scenes (surface and geographical positions are provided in red on each panel). Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 28
Quality Assessment of SYN VGT like TOA and Surface reflectance:
One main objective of SYNERGY processing chains is to ensure the continuity of the VEGETATION like products, as PROBA-V products. Comparisons with PROBA-V datasets have therefore been performed to evaluate the quality of SYNERGY VGT-like products.
SYN VGT-like products have been compared to consistent PROBA-V products (i.e. acquiring same area on the same date). This analysis has been conducted on SY_2_V10, SY_2_VG1 and SY_2_VGP products focusing on European and African sites and on “good_quality” data. Only results obtained on SY_2_V10 are displayed below.
Several limitations need to be considered before analysing results: differences in spectral response or in absolute calibration, especially concerning SWIR bands; differences in atmospheric correction, differences about overpass time (i.e. regarding illumination angles) and about observation angles; …
Despite these differences, a good correlation can be observed between B0, B2 and B3 surface reflectances. Systematic bias can be observed on MIR reflectances, consistent with the known calibration issue of SLSTR S5 and S6 bands.
Figure 12: Statistical consistency between SYNERGY S3A VGT-S10 products and PROBA-V decadal composite over VGT surface reflectance Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 29
Figure 13: Statistical consistency between SYNERGY S3B VGT-S10 products and PROBA-V decadal composite over VGT surface reflectance
7.2 Known limitations of SYNERGY Products
Besides the over-estimation of the retrieved AOD datasets, SYNERGY products can be affected by similar cameras interface than OLCI datasets.
In addition, the interface between nadir-only and dual view area can be highly visible specially in case of low NDVI. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 30
8 Helpdesk
8.1 Access and use of SYN products
8.1.1 How to get access to SYN products?
The Copernicus programme has adopted a free, full and an open data policy for all users.
The main source of access to OLCI products is the Copernicus Data Hub, accessible at this address: https://scihub.copernicus.eu. A simple self-registration is necessary to access the service. The hub also gives news and further information about the service.
Access can be done via a graphical user interface or via the API Hub which allows to run scripts without going through the graphical interface.
In addition to the download services, the SENTINEL Data Products are also available in the Copernicus Data and Information Access Service (DIAS) cloud environments. Each DIAS provides processing resources, tools and complimentary data sources at commercial conditions to further facilitate the access to SENTINEL data.
Note that currently (2020) SY_2_AOD products are not distributed to users as their validation is not consolidated yet.
8.1.2 How to read and display the SYN products?
Since SYNERGY products are composed of a set of netcdf files and a manifest file in xml format, there exist many software allowing to open these files.
In addition to these individual tools (not listed here), the SENTINEL-3 Toolbox is particularly well adapted to SYNERGY products (and SLSTR and OLCI products). It is composed of a set of visualisation, analysis and processing tools for the data usage. It is worth noting that 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.
Once SNAP has been downloaded and installed, it is very easy to open L2 SYNERGY products, by just opening the xfdumanifest.xml file, from which all other netcdf files can be read and displayed.
8.2 FAQ
Where can I find information about the latest version of processing?
❖ Every time a new major version of the processing chain is deployed, a Product Notice is released in which the main changes are summarised; the notice gives a status of the performances as well as all known anomalies not already fixed.
❖ All PNs are available in the SENTINEL Online web site. Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 31
What is a Processing Baseline?
❖ A processing baseline (PB) is composed of one IPF version and a set of ADFs. Any change, affecting the version of the IPF or of at least one ADF, increments the version of the PB.
❖ While the PB version is indicated in the Product Notice, it is not included in the product manifest.
How can I find the IPF or the ADF version used for the processing?
❖ This information is included in the manifest of all products.
❖ In Figure 14 and Figure 15, examples are given showing the version of the IPFs used (all levels are available) and the version of the ADF used.
Figure 14: IPF version in xfdumanifest.xml
Figure 15: ADF version xfdumanifest.xml Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 32
❖ Information about the successive processing baselines is also available in SENTINEL Online, in the form of timelines as shown in Figure 16
Figure 16: S3A processing baseline timelines (dated on 23-06-2020)
Figure 17: S3B processing baseline timelines (dated on 23-06-2020)
If I want to know about past anomalies or events, how can I get the information?
❖ A specific page is available in SENTINEL Online providing all information about anomalies or events affecting the NTC products, as shown in Figure 18 Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 33
Figure 18: Calendar view of anomalies and events impacting SYNERGY in 2020, note that any anomalies impacting OLCI or SLSTR L1 products will be automatically considered for SYNERGY
8.3 If you have a question
The Services Coordinated Interface (SCI) is the user service dedicated to Copernicus users. The SCI handles the Copernicus users' enquiries, orders and complaints, and coordinates the data provision according to user requirements and data offer.
While SENTINEL dedicated information is available in the present pages, the Copernicus Space Component Data Access system (CSCDA) web site is the entry point for obtaining information regarding the global data offer, available tools and data provision status.
The SCI is available for user support; they can be contacted via email at [email protected] for support, in particular for:
❖ Clarifications regarding the registration process
❖ SENTINEL enquiries
❖ Reporting issues related to products/service quality
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 34
8.4 Useful links
8.4.1 About Copernicus ❖ CSCDA: https://spacedata.copernicus.eu
❖ EU Copernicus: https://www.copernicus.eu/en
❖ ESA Copernicus: http://www.esa.int/Applications/Observing_the_Earth/Copernicus
8.4.2 About ESA and the SENTINELs missions ❖ ESA website: http://www.esa.int
❖ SENTINEL Online: https://sentinel.esa.int/web/sentinel/home
8.4.3 About SYN ❖ User guides: https://sentinel.esa.int/web/sentinel/user-guides/sentinel-3-synergy
❖ Technical guide: https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-3-synergy
❖ Processing Baselines information: https://sentinel.esa.int/web/sentinel/technical- guides/sentinel-3-synergy/processing-baseline
❖ Anomalies and Events related to SYNERGY: https://sentinel.esa.int/web/sentinel/technical- guides/sentinel-3-synergy/anomalies-and-events
8.4.4 About S3 toolbox ❖ STEP: http://step.esa.int/main/download/
❖ Forum: https://forum.step.esa.int
Ref.: S3MPC.ACR.HBK.003 Copernicus Sentinel-3 SYN Land User Issue: 1.1 Handbook Date: 28/04/2021
Page: 35
8.5 Acronyms and abbreviations
ADF Auxiliary Data File API Application Programming Interface ATBD Algorithm Theoretical Basis Document CSCDA Copernicus Space Component Data Access DIAS Copernicus Data and Information Access Service EO Earth Observation ESA European Space Agency IPF Instrument Processing Facility MODIS Moderate Resolution Imaging Spectroradiometer NASA National Aeronautics and Space Administration NDVI Normalized Difference Vegetation Index NetCDF Network Common Data Format NTC Non Time Critical OLCI Ocean and Land Colour Instrument PDFS Product Data Format Specification PDGS Payload Data Ground Segment PDU Product Dissemination Unit POD Precise Orbit Determination PUG Product Unit Generator SAFE Standard Archive Format for Europe SNAP Sentinel Applications Platform STEP Science Toolbox Exploitation Platform TOA Top of Atmosphere UTC Coordinated Universal Time XML Extensible Markup Language XFDU XML Formatted Data Units WGS84 World Geodetic System 1984
End of the document