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Proba-V QWG-09

Proba-V and S3-SYN SNAP Toolbox: status and updates

Carsten Brockmann, Marco Peters

18.04.2019

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Proba-V SNAP Toolbox

1. Reading Antarctica data• Report at QWG8: not possible to read

• Reason: reader issue with netCDF (used for Proba-V HDF5 reader)

• First fix: correctly interpreting the HDF product

• reader version 7.0.0, implemented in SNAP7

• Remaining issue: no geo-coding attached; problem to decode the crs (Antarctic Polar Stereographic)

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SNAP 6

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SNAP 7

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Proba-V SNAP Toolbox

1. Reading Antarctica data• Report at QWG8: not possible to read

• Reason: reader issue with netCDF (used for Proba-V HDF5 reader)

• First fix: correctly interpreting the HDF product

• reader version 7.0.0, implemented in SNAP7

• Remaining issue: no geo-coding attached; problem to decode the crs (Antarctic Polar Stereographic)

2. Cloud Shadow• Method presented at QWG8

• Improvement of geometry calculation

• Application to OLCI, including CTP estimation (not relevant for PB-V)

• Implementation for Proba-V planned within ESA Ideas+ framework

• Completion October 2019

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Cloud and Mountain Shadow

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Example S2 (20171029T075031 T35JPM)

Clustered cloud shadow Shifted cloud shadow Coinciding cloud shadow

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Geometric calculation (true shadow)view

sun

Projected

position

cloud

Actual position

(nadir)

shadow

Projected

position

Actual position

(nadir)shadow

Apparent Sun azimuth

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Example – OLCI (20181029T103744)

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Proba-V SNAP Toolbox

1. Reading Antarctica data• Report at QWG8: not possible to read• Reason: reader issue with netCDF (used for Proba-V HDF5 reader)• First fix: correctly interpreting the HDF product

• reader version 7.0.0, implemented in SNAP7• Remaining issue: no geo-coding attached; problem to decode the crs (Antarctic Polar Stereographic)

2. Cloud Shadow• Method presented at QWG8

• Improvement of geometry calculation• Application to OLCI, including CTP estimation (not relevant for PB-V)

• Implementation for Proba-V planned within ESA Ideas+ framework• Completion by October 2019

3. Snow Albedo• Method presented at QWG8 for Sentinel 3• Investigation by A. Kokhanovsky to apply method to 4 PBV bands

• Theoretically it should work• Tested on Greenland data problem of saturated pixels• With the updated reader we can provide Alex the Antarctica data

• Voluntary activity, progress depends on time availability of A. Kokhanovsky and BC

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Sentinel 3 Level 1C OLCI SLSTR SYN Tool

Marco Peters & Roman Shevchuk, BC; Claire Henoq, ACRI-ST; Alberto Monescillo, deimos-space

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Objectives

• Requirements by Copernicus Global Land Monitoring Service, futureCopernicus Climate Service, and also ESA CCI Snow

• To obtain a product where the two Level 1b data streams from Sentinel 3 OLCI and SLSTR (TOA radiances or reflectances) are merged and collocated, and which allows them their specific and individual Level 2 processing.

• After discussion between users, ESA and EC it was decided to provide a tool • allows generation of the required L1C SYN product as required by the services

• allows the different configurations which are required by the different users

• implement under SNAP, as plug-in to the Sentinel 3 toolbox• The core functionality (OLCI & SLSTR coregistration) will be available as a Java library without

SNAP dependencies (CCI SNOW requirement)

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L1C SYN Tool Overview

• Coregister OLCI and SLSTR L1b data product to a L1C SYN data product

• Allow to create spatial subset of the inputs

• Basically include all bands from both sensors• Allow to select a subset of bands in the output

• The output can be resampled to a new resolution

• The resulting L1C data product can be reprojected to a user defined CRS

• Options• Uncertainty calculation

• Misregistration calculation for other sensors

• Apply cloud screening / flags bands added

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Development in 3 versions• Version 1 (done)

• Rely on geolocation on OLCI and SLSTR image grids as in L1b products• Use SNAP collocation operator• Coregister OLCI and SLSTR L1b data product to a L1C SYN data product lat-lon grid• Include only a selection of bands in the output as required by CGLOPS• Main purpose:

• Support development of Version 2• Provide an engineering prototype for CGLOPS (iteration with VITO is very ongoing and very useful)

• Version 2.0• Use of misregistration file

• Best possible coregistration accuracy• Provide tool to CGLOPS which fulfils their requirements

• Version 2.x• Adding functionalities for other users (other target grids, in particular OLCI and SLSTR image

grids, Proba-V tile grid writer, output format, library version, …)

• Version 3 (end of 2019)• Additional user options for output configuration• Optional features as ordered by ESA

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Version 1

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V1 Example

• Inputs• OLCI FR product, Strait of Gibraltar

• 4865 x 4091 pixels @ 300m, OLCI image grid• 30+ bands (89) + tie points, 664MB uncompr.

• SLSTR• 3000 x 2400 pixels @ 500m, SLSTR image grid• 111+ bands + tie-point, 557MB uncompressed

• Processing• OLCI reprojection to output coordinate reference system

• Pixel-based geocoding of OLCI (irregular grid search)

• Collocation of SLSTR to OLCI• Reprojecting all tie-point grids (expanding)• Updating meta data• Writing bands• processing time 1:50 hours on Desktop PC

• Output• SYN L1C product• 5395 x 4091 pixels @ 300m, lat-lon grid• 412 bands, 5.32GByte netCDF

OLCI, band 17 (865nm) SLSTR nadir, S3 (868nm)

SYN L1C band Oa_17 (OLCI 865nm)

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OLCI

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SLSTR nadir

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OLCI

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SLSTR-nadir

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SLSTR-oblique

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OLCI

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SLSTR-nadir

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SLSTR-oblique

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S3 L1C SYN Tool Roadmap

• V1 engineering tool, January 2019

• V2.0 CGLOPS version, April/May 2019

• V2.x public SNAP versions with user options

• V3.0 final version, December 2019

• EUMETSAT study for OLCI & SLSTR cloud masks using synergisticallyboth instruments• June 2019 - end of 2020