Sentinel-3 Marine Test Data Set processed at EUMETSAT

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Doc.No. : EUM/TSS/TEN/15/822144

Issue : v2 e-signed

Date : 15 December 2015

WBS/DBS :

Sentinel-3 Marine Test Data Set processed at

EUMETSAT

EUMETSAT Eumetsat-Allee 1, D-64295 Darmstadt, Germany Tel: +49 6151 807-7 Fax: +49 6151 807 555 http://www.eumetsat.int

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Document Change Record

Issue / Revision

Date DCN.

No

Changed Pages / Paragraphs

V1 04.09.2015 Draft version – only one PDU

V1A 04.09.2015 First version - full orbit of SLSTR L1 and OLCI L1 FR

data

V1B 10.09.2015 Version prepared for publishing

V2 15.12.2015 Added SRAL L1b data from STC production chain,

consolidated main document body and added some new limitations to existing data.

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1 INTRODUCTION ... 5 1.1 Purpose ... 5 1.2 Scope ... 5 1.3 Reference Documents ... 5 2 MARINE USER TDS ... 7 2.1 Overview ... 7 2.1.1 Contents ... 7 2.1.2 TDS Generation ... 8 2.1.3 Data Visualisation ... 9 2.1.4 TDS Delivery ... 10 2.1.5 Feedback on TDS ... 10 2.2 SLSTR TDS ... 10 2.2.1 Description ... 10 2.2.2 SLSTR current limitations ... 11 2.3 OLCI TDS ... 12 2.3.1 Description ... 12

2.3.2 OLCI current limitations ... 12

2.4 SRAL TDS ... 13

2.4.1 Description ... 13

2.4.2 SRAL current limitations ... 14

APPENDIX A SUMMARY OF CURRENT LIMITATIONS ... 16

APPENDIX B PRODUCT LIST ... 17

Table of Figures Figure 1. Example of footprints for different grids in one PDU for selected product SL_1_RBT___: footprint defined in manifest file (red), 1 km nadir (yellow) and 1 km oblique (black) view. ... 11

Figure 2. Example of brightness temperatures of channel S8 for nadir (left) and oblique (right) view. . 11

Figure 3. Example of OL_1_EFR___ top of the atmosphere (TOA) radiance in band 1 (left) and band 10 (right). All values in selected TOA radiance bands are plotted, regardless of the flag values. ... 12

Figure 4: Footprints of the ground tracks for the TDS pole-to-pole passes ... 13

Figure 5: Ku SAR Waveforms Data for Orbit 285 ... 14

Figure 6: Ku LRM Waveforms Data for Orbit 285 ... 14

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1 INTRODUCTION

1.1 Purpose

A Sentinel-3 marine simulated Test Data Set (TDS) is generated by Payload Data Ground Segment (PDGS) deployed at the EUMETSAT Sentinel-3 Marine Centre. It represents the data that are produced using the current version of the Processing Facility. It has to be noted that the version of Processing Facility and the products specification might evolve after the release of this TDS with the consequent change of their content and format.

This Technical Note provides a description of the Sentinel-3 marine simulated OLCI/SLSTR/SRAL L1 TDS, its structure and contents, its limitations and open issues. It explains how to access the TDS and feed-back comments to EUMETSAT.

This Issue addresses the Version 2 of the Marine TDS.

It is expected that this document will be updated for future versions of the S3 Marine TDS when OLCI/SLSTR/SRAL L2 products will become available. It is encouraged that the users interested in this products but also in the updated version of available TDS, send email to [email protected] with the subject “Sentinel-3 Marine TDS subscription”. EUMETSAT help desk will ensure that interested users will receive the last available TDS with updated Technical Note describing the data and updates.

1.2 Scope

This Technical Note is aimed for the wide Users’ community that are preparing tools and applications for marine Sentinel-3 products and want to have access to Sentinel-3 SAFE product formats. Since the data values are not scientifically meaningful, it is not expected to be used for scientific testing.

1.3 Reference Documents

RD-1 Sentinel-3 Optical User TDS description

https://sentinel.esa.int/web/sentinel/toolboxes/sentinel-3

RD-2 Product Data Format Specification - SRAL/MWR Level 1 & 2 Instrument Product

S3IPF.PDS.003

RD-3 Product Data Format Specification - OLCI Level 1 & 2 Instrument Product

S3IPF.PDS.004

RD-4 Product Data Format Specification - SLSTR Level 1 & 2 Instrument Product

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RD-5 GMES Space Component - Sentinel-3 Payload Data Ground Segment Products Definition Document

GMES-S3GS-EOPG-TN-12-0004 EUM/LEO-SEN3/TEN/13/720910

RD-6 Sentinel-3 S3-TDS Generation for L2 SRAL/MWR IPF

https://sentinel.esa.int/web/sentinel/user-guides/sentinel-3-altimetry/test-data-set CLS-DOS-NT-15-038

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2 MARINE USER TDS

2.1 Overview

A Sentinel-3 marine simulated TDS is generated by PDGS deployed at the EUMETSAT Sentinel-3 Marine Centre. It represents the data that are produced using the latest available Instrument Processing Facility (IPF) version and, with a few smaller modifications, representative of the processing that will be used after the launch of Sentinel-3A. In particular the product format should closely resemble the format that will be available during the commissioning phase, allowing users to get experience with the Sentinel-3 SAFE marine products.

This TDS is complementary to scientifically meaningful TDS distributed by ESA (RD-1, RD-6) because it represents the data generated directly by the PDGS facility, but with very limited scientifically meaningful content. Therefore, users are advised to use both the scientific TDS mentioned above and this simulated TDS to prepare tools and applications for their upcoming Sentinel-3 activities.

Some limitations and open issues in this TDS are listed below and under investigation. Users are invited to note those, to have a detailed and critical view and to provide feedback to EUMETSAT.

2.1.1 Contents

This TDS covers L1 products from both optical and surface topography mission (STM). Optical TDS contains one simulated orbit of OLCI Level 1 full resolution (FR) and SLSTR Level 1 products distributed in 3 minute Product Dissemination Units (PDUs):

- OLCI: OL_1_EFR___

- SLSTR: SL_1_RBT___

STM TDS contains 6 simulated descending pole-to-pole (i.e. ~ 50 minute long PDU) SRAL L1b passes in STC timeliness.

- SRAL: SR_1_SRA___

SRAL L2, SLSTR L2 and OLCI RR L1 and L2 (RR/FR) from other production chains will be distributed to users in a future version.

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Table 1) gives the estimated size of the TDS. For the exact size of PDUs please refer to Table 6 in Appendix B.

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Table 1. Estimated product sizes of this TDS. Based on the compression rate, size of the operational products can vary.

Product name PDU size (MB) Cumulative size for one

orbit (GB)

SL_1_RBT___ 300-400 MB ~13 GB

OL_1_EFR___ 350-450 MB ~ 5 GB

SR_1_SRA___ 20-40 MB ~ 0.05 GB

2.1.2 TDS Generation

The TDSs provided to users include simulated high level products produced by the Sentinel-3 Marine PDGS. Products are provided in PDUs, defined as portion of data [RD-5] in order to ease the online dissemination and data handling for the users. These PDUs are produced by the following elements:

Table 2. TDS production elements

OLCI IPF version 5.02

SLSTR IPF version 5.02

SRAL IPF version 5.02

For OLCI and SLSTR payload, PDUs are generated by Product Unit Generation Facility (PUGF) in the near real time (NRT) processing chain in frames [RD-5] with the length of 3 minutes. For SRAL payload in the L1b short time critical (STC) processing chain, PUGF generates PDUs in pole-to-pole passes [RD-5] with an approximate length of 50 minutes.

We will give brief information on selected Sentinel-3 marine products, and report some existing limitations.

One orbit (#287) is selected for OLCI Level 1 FR and SLSTR Level 1 in NRT production chain (Table 3) and 6 descending pole-pole passes of SRAL L1 in STC production chain (Table 4). All PDU filenames are listed in Table 6 of Appendix B.

Table 3.Simulated orbit characteristics for OLCI and SLSTR

Orbit 287

UTC Time at ascending node 2013-07-07T23:19:48.341135Z Position at ascending node in Earth Fixed

frame [m]

X: 6752784.9879999999 Y:-2450656.2609999999 Z:-9.5220000000000002

Table 4.Simulated orbit characteristics for SRAL

Orbit 285

UTC Time at ascending node 2013-07-07T19:57:49.899613Z Position at ascending node in Earth Fixed

frame [m]

X: 6186699.9050000003 Y 3651104.6949999998 Z: 2.2530000000000001

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Orbit 286

frame [m]

X: 7153002.0980000002 Y 663612.98300000001 Z: -4.0190000000000001

Orbit 289

frame [m]

X: 2405080.0240000002 Y -6769151.4450000003 Z: -14.35

Orbit 290

frame [m]

X: -711816.32700000005 Y -7148366.1579999998 Z: -12.76

Orbit 291

frame [m]

X: -3692726.3130000001 Y -6161947.2230000002 Z: -8.7289999999999992

Orbit 293

frame [m]

X: -7103451.4189999998 Y -1070887.0819999999 Z: 3.254

2.1.3 Data Visualisation

For visualising data or accessing the manifest file users are encouraged to use the Sentinel-3 Toolbox [RD-1] or any other tool able to visualise NetCDF-4 and read XML files (Python, Matlab/Octave, IDL, ...).

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2.1.4 TDS Delivery

TDS are available at the following URL:

ftp://ftp.eumetsat.int/pub/OPS/out/test-data/Sentinel-3A_Test_Data/ The TDS directory structure is as follows:

OLCI_(Ocean_Land_Colour_Instrument)/ Level-1_Full_Resolution/ OL_1_EFR____NRT/ SLSTR_(Sea_Land_Surface_Temperature_Radiometer)/ Level-1/ SL_1_RBT____NRT/ SRAL_(SAR_Radar_ALtimeter)/ Level-1/ SR_1_SRA____STC/ 2.1.5 Feedback on TDS

TDS users are invited to provide comments on the TDS by email to the EUMETSAT Help Desk [email protected].

2.2 SLSTR TDS

2.2.1 Description

The SLSTR product data format specification (PDS) document [RD-4] describes SLSTR Level 1 and Level 2 products in detail.

This TDS contains one orbit of SL_1_RBT___ Level 1 in NRT (two PDUs are missing). The estimated size for one PDU and for one orbit of SL_1_RBT___ product is shown in

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Table 1. It should be noted that this products are internally compressed (compression ratio 2) and the sizing is based on simulated data. Therefore the size of the real product can differ from these values.

Figure 1 shows an example of footprints for different grids in one selected SL_1_RBT___ PDU: 1 km nadir view (yellow), 1 km oblique view (black) and satellite footprint defined in manifest file (red). Example of band S8 nadir and oblique view brightness temperatures (Figure 2) shows simulated values over the whole acquisition area.

Figure 1. Example of footprints for different grids in one PDU for selected product SL_1_RBT___: footprint defined in manifest file (red), 1 km nadir (yellow) and 1 km oblique (black) view.

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Figure 2. Example of brightness temperatures of channel S8 for nadir (left) and oblique (right) view.

2.2.2 SLSTR current limitations

1. Missing two SL_1_RBT PDUs from the full orbit.

2. Satellite footprint points defined in the manifest file are not sorted correctly for several SL_1_RBT___ products.

3. Measurement values along the SL_1_RBT___ product edges contain missing values. 4. Some missing values along the scan line are not correctly flagged.

5. Meteorological variables are not filled with correct values.

6. Discrepancy between the acquisition start/stop times defined in the manifest file, in the global attribute header of data files and of the data itself (e.g. time_in.nc).

2.3 OLCI TDS

2.3.1 Description

OLCI product data format specification (PDS) document [RD-3] describes OLCI Level 1 and Level 2 products in detail. This TDS contains one orbit of OL_1_EFR___ L1 full resolution products. Similar to SLSTR,

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Table 1 shows the estimated size for one PDU and the size of the one orbit. Again, it should be noted that this product sizing is based on simulated data and the size of the real product can significantly differ from this values.

Figure 3 shows example of simulated top of the atmosphere radiances for band 1 and 10 for one OL_1_EFR___ PDU selected over the same area and covering the same acquisition time as shown for SLSTR (Figure 2).

Figure 3. Example of OL_1_EFR___ top of the atmosphere (TOA) radiance in band 1 (left) and band 10 (right). All values in selected TOA radiance bands are plotted, regardless of the flag values.

2.3.2 OLCI current limitations

1. Two OL_1_EFR PDUs have shorter duration time.

2. Measurement values along the OLCI product edges are filled with zeros, and the _FillValue is defined as 65535US.

3. There is a discontinuity in geodetic longitude/latitude OLCI L1 products and values. These values are flagged as invalid pixels (and therefore not shown in S3TBX).

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In this TDS version, 6 descending pole-to-pole STC L1b passes are available (orbit number 285, 286, 289, 290, 291 and 293). The corresponding ascending passes are not delivered.

The estimated size for one L1b pass (PDU) and for the full orbit of L1b SR_1_SRA product is shown in

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Table 1. Again, it should be noted that this product sizing is based on simulated data and the size of the real product can differ from this values.

The products may feature some temporal gaps of around 0.25 seconds. These gaps are due to the transition between SAR mode and LRM mode (and vice versa) or the lost/corrupt source packets; they are anyhow logged in the manifest file.

The Figure 4 shows the footprints for the 6 descending passes (blue is LRM mode and red is SAR mode).

Figure 4: Footprints of the ground tracks for the TDS pole-to-pole passes

The Figure 5 and Figure 6 Figure 4show respectively the Ku Waveforms Data for the SAR mode and LRM mode for the orbit 285 (descending pass).

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Figure 5: Ku SAR Waveforms Data for Orbit 285

Figure 6: Ku LRM Waveforms Data for Orbit 285

We stress again that the data are not scientifically meaningful and therefore users should use the data mainly to get familiar to the Sentinel-3 SAFE format and build the software interfaces to it.

2.4.2 SRAL current limitations

1. Non-conformance to CF 1.6 convention.

2. Discrepancy between the product name as reported in the manifest and the product name as reported in the global attribute header of the measurement data file

3. Discrepancy between the sensing start/stop time in the manifest and in the global attribute header of measurement/annotation data files.

4. Inconsistency between the product footprint as reported in the product manifest and real footprint of the product (lat/lon in the measurement data file).

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APPENDIX A SUMMARY OF CURRENT LIMITATIONS

Table 5. List of current limitations.

Instrument Current limitations

SLSTR

- Missing two SL_1_RBT PDUs from the full orbit. - One SL_1_RBT PDU has shorter duration time.

- Satellite footprint points defined in the manifest file are not sorted correctly for several SL_1_RBT___ products.

- Measurement values along the SL_1_RBT___ product edges contain missing value.

- Some missing values along the scan line not correctly flagged in SL_1_RBT.

- Meteorological variables within met_tx.nc annotation data file are filled with constant non-meaningful values.

- Discrepancy between the acquisition start/stop times defined in the manifest file, in the global attribute header of data files and of the data itself.

OLCI

- Two OL_1_EFR___ PDUs have shorter duration time.

- Measurement values along the OL_1_EFR___ product edges are filled with zeros, and the _FillValue is defined as 65535US.

- There is a discontinuity in geodetic longitude/latitude OL_1_EFR___ products and values. These values are flagged as invalid pixels (and therefore not shown in S3TBX).

- Discrepancy between the acquisition start/stop times defined in the manifest file, in the global attribute header of data files and of the data itself.

SRAL

- Non-conformance to CF 1.6 convention.

- Discrepancy between the product name as reported in the manifest and the product name as reported in the global attribute header of the measurement data file

- Discrepancy between the sensing start/stop time in the manifest and in the global attribute header of measurement/annotation data files.

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APPENDIX B PRODUCT LIST

Table 6. List of PDUs and corresponding sizes. Instrument Product file name

SLSTR SL_1_RBT___ 391M S3A_SL_1_RBT____20130707T234917_20130707T235216_20150806T181829_ 0179_015_287_1768_MAR_O_NR_001.SEN3 358M S3A_SL_1_RBT____20130707T235517_20130707T235816_20150806T183903_ 0179_015_287_2128_MAR_O_NR_001.SEN3 381M S3A_SL_1_RBT____20130707T235217_20130707T235516_20150806T181959_ 0179_015_287_1948_MAR_O_NR_001.SEN3 354M S3A_SL_1_RBT____20130707T234617_20130707T234916_20150806T183432_ 0179_015_287_1588_MAR_O_NR_001.SEN3 354M S3A_SL_1_RBT____20130707T234317_20130707T234616_20150806T183334_ 0179_015_287_1408_MAR_O_NR_001.SEN3 135M S3A_SL_1_RBT____20130707T233612_20130707T233716_20150806T183747_ 0064_015_287_0984_MAR_O_NR_001.SEN3 389M S3A_SL_1_RBT____20130707T233717_20130707T234016_20150806T183758_ 0179_015_287_1048_MAR_O_NR_001.SEN3 346M S3A_SL_1_RBT____20130708T000717_20130708T001016_20150806T192816_ 0179_015_287_2848_MAR_O_NR_001.SEN3 308M S3A_SL_1_RBT____20130708T003117_20130708T003416_20150806T203150_ 0179_015_287_4288_MAR_O_NR_001.SEN3 389M S3A_SL_1_RBT____20130707T234017_20130707T234316_20150806T184144_ 0179_015_287_1228_MAR_O_NR_001.SEN3 353M S3A_SL_1_RBT____20130707T233117_20130707T233416_20150806T192246_ 0179_015_287_0688_MAR_O_NR_001.SEN3 369M S3A_SL_1_RBT____20130708T001017_20130708T001316_20150806T192541_ 0179_015_287_3028_MAR_O_NR_001.SEN3 353M S3A_SL_1_RBT____20130707T235817_20130708T000116_20150806T192523_ 0179_015_287_2308_MAR_O_NR_001.SEN3 335M S3A_SL_1_RBT____20130708T000417_20130708T000716_20150806T192632_ 0179_015_287_2668_MAR_O_NR_001.SEN3 310M S3A_SL_1_RBT____20130708T001617_20130708T001916_20150806T193349_ 0179_015_287_3388_MAR_O_NR_001.SEN3 288M S3A_SL_1_RBT____20130708T002517_20130708T002816_20150806T201743_ 0179_015_287_3928_MAR_O_NR_001.SEN3 364M S3A_SL_1_RBT____20130707T232517_20130707T232816_20150806T191752_ 0179_015_287_0328_MAR_O_NR_001.SEN3 299M S3A_SL_1_RBT____20130708T001317_20130708T001616_20150806T193223_ 0179_015_287_3208_MAR_O_NR_001.SEN3 286M S3A_SL_1_RBT____20130708T002217_20130708T002516_20150806T193637_ 0179_015_287_3748_MAR_O_NR_001.SEN3 351M S3A_SL_1_RBT____20130707T232817_20130707T233116_20150806T192140_ 0179_015_287_0508_MAR_O_NR_001.SEN3 348M S3A_SL_1_RBT____20130708T000117_20130708T000416_20150806T192745_ 0179_015_287_2488_MAR_O_NR_001.SEN3 295M S3A_SL_1_RBT____20130708T001917_20130708T002216_20150806T193530_ 0179_015_287_3568_MAR_O_NR_001.SEN3 309M S3A_SL_1_RBT____20130708T002817_20130708T003116_20150806T203110_ 0179_015_287_4108_MAR_O_NR_001.SEN3 349M S3A_SL_1_RBT____20130708T005517_20130708T005816_20150806T203656_ 0179_015_287_5728_MAR_O_NR_001.SEN3 342M S3A_SL_1_RBT____20130708T005817_20130708T010116_20150806T204025_ 0179_015_287_5908_MAR_O_NR_001.SEN3 341M S3A_SL_1_RBT____20130708T004917_20130708T005216_20150806T204204_ 0179_015_287_5368_MAR_O_NR_001.SEN3 337M S3A_SL_1_RBT____20130708T005217_20130708T005516_20150806T204259_ 0179_015_287_5548_MAR_O_NR_001.SEN3 350M S3A_SL_1_RBT____20130708T004017_20130708T004316_20150806T204753_ 0179_015_287_4828_MAR_O_NR_001.SEN3 349M S3A_SL_1_RBT____20130708T004317_20130708T004616_20150806T204834_ 0179_015_287_5008_MAR_O_NR_001.SEN3 346M S3A_SL_1_RBT____20130708T004617_20130708T004916_20150806T204942_ 0179_015_287_5188_MAR_O_NR_001.SEN3

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308M S3A_SL_1_RBT____20130708T003417_20130708T003716_20150806T205349_ 0179_015_287_4468_MAR_O_NR_001.SEN3 342M S3A_SL_1_RBT____20130708T003717_20130708T004016_20150806T205444_ 0179_015_287_4648_MAR_O_NR_001.SEN3 OLCI OL_1_EFR___ 13M S3A_OL_1_EFR____20130707T234012_20130707T234016_20150806T174736_ 0004_015_287_1224_MAR_O_NR_001.SEN3 445M S3A_OL_1_EFR____20130707T234017_20130707T234316_20150806T172652_ 0179_015_287_1228_MAR_O_NR_001.SEN3 385M S3A_OL_1_EFR____20130707T234317_20130707T234616_20150806T172852_ 0179_015_287_1408_MAR_O_NR_001.SEN3 374M S3A_OL_1_EFR____20130707T234617_20130707T234916_20150806T174223_ 0179_015_287_1588_MAR_O_NR_001.SEN3 428M S3A_OL_1_EFR____20130707T234917_20130707T235216_20150806T175947_ 0179_015_287_1768_MAR_O_NR_001.SEN3 392M S3A_OL_1_EFR____20130707T235217_20130707T235516_20150806T181111_ 0179_015_287_1948_MAR_O_NR_001.SEN3 404M S3A_OL_1_EFR____20130708T001317_20130708T001616_20150806T193244_ 0179_015_287_3208_MAR_O_NR_001.SEN3 364M S3A_OL_1_EFR____20130708T000117_20130708T000416_20150806T200619_ 0179_015_287_2488_MAR_O_NR_001.SEN3 366M S3A_OL_1_EFR____20130707T235517_20130707T235816_20150806T181914_ 0179_015_287_2128_MAR_O_NR_001.SEN3 365M S3A_OL_1_EFR____20130707T235817_20130708T000116_20150806T183254_ 0179_015_287_2308_MAR_O_NR_001.SEN3 376M S3A_OL_1_EFR____20130708T000717_20130708T001016_20150806T184310_ 0179_015_287_2848_MAR_O_NR_001.SEN3 133M S3A_OL_1_EFR____20130708T000612_20130708T000716_20150806T192146_ 0064_015_287_2784_MAR_O_NR_001.SEN3 439M S3A_OL_1_EFR____20130708T001617_20130708T001916_20150806T190439_ 0179_015_287_3388_MAR_O_NR_001.SEN3 413M S3A_OL_1_EFR____20130708T001017_20130708T001316_20150806T191232_ 0179_015_287_3028_MAR_O_NR_001.SEN3 391M S3A_OL_1_EFR____20130708T001917_20130708T002216_20150806T194438_ 0179_015_287_3568_MAR_O_NR_001.SEN3 SRAL SR_1_SRA___ 26.6M S3A_SR_1_SRA____20130707T202304_20130707T211334_20151206T164300_ 3029_015_285______MAR_O_ST_001.SEN3 26.8M S3A_SR_1_SRA____20130707T220404_20130707T225434_20151206T164659_ 3029_015_286______MAR_O_ST_001.SEN3 31.1M S3A_SR_1_SRA____20130708T030701_20130708T035731_20151206T200940_ 3029_015_289______MAR_O_ST_001.SEN3 31.4M S3A_SR_1_SRA____20130708T044801_20130708T053830_20151206T191240_ 3029_015_290______MAR_O_ST_001.SEN3 31.5M S3A_SR_1_SRA____20130708T062900_20130708T071930_20151206T215751_ 3029_015_291______MAR_O_ST_001.SEN3 31.7M S3A_SR_1_SRA____20130708T095058_20130708T104128_20151206T182139_ 3029_015_293______MAR_O_ST_001.SEN3

Sentinel-3 Marine Test Data Set processed at EUMETSAT

Sentinel-3 Marine Test Data Set processed at

EUMETSAT

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