sentinel-3 products

Sentinel-3 calibration and Validation Planning Meeting ESA/ESRIN, Frascati, Italy, 20-22nd March 2012

Pierre Féménias, Philippe Goryl

ESA / ESRIN

Sentinel-3 Products


OUTLINE

- Generic information

- Optical Sensors products

- Altimetry Products

- Conclusion

Sentinel-3 calibration and Validation Planning Meeting ESA/ESRIN, Frascati, Italy, 20-22nd March 2012 3

• The Sentinel Mission Requirements Documents:

• S-3: EOP-SMO/1151/MD-md, Is: 2.0

• The Data Access Portfolio and the Data Warehouse documents

• DAP: GMES-PMAN-EOPG-TN-07-0003 Is 1.0

• GMES Service Projects requirements captured in the EC data warehouse

document

• Key mission concepts:

• Operational Missions with well identified operational users communities

(e.g. GMES Projects)

• Ensure continuity with existing services (e.g. ENVISAT based services)

Background and Framework Background and Framework


The data volume of Sentinel-1,-2,-3 A-series production is equivalent to ˜25 ENVISAT missions with:

– Systematic processing of all Sentinels data System Requirement: ‘All observation data acquired by Sentinels shall be systematically processed to a pre-determined product level for each sensor type, archived and made available for on-line access to end-users. ‘

– Highly configurable data driven production, products are available as soon as produced No backlog accumulation under nominal conditions

– For S-3, 3 main categories of operational latency customized according to mission production and consolidation requirements, acquisition areas and Payload Data Ground Segment resources Near Real Time: 3h, Non Time Critical and STC : Short Time Critical only for SRAL

The PDGS commissioning activities will be conducted in parallel to the satellite (platform and payload) commissioning, including calibration and validation of the products. Data availability and data quality will follow a progressive ramp-up scenario starting at launch. "

Sentinels Core Ground Segment Production Highlights

Sentinels Core Ground Segment Production Highlights


Sentinel - 3 GSC Core GS User Products list

LEVEL 1

- OLCI L1B

- SLSTR L1B

LEVEL 2

- OLCI ocean color

- SLSTR sea

- SRAL L2

LEVEL 2

- OLCI Land

- SLSTR Land

- SYNERGY / VGT

- SRAL L2

Marine products

EUMETSAT

Land products

ESA

Level 1

ESA/EUMETSAT

Sentinel - 3 GSC Core GS User Products list


Sentinels Core Products Products Format

A unique packaging concept adapted to the different missions user

communities

XML Schema files for measurement data and annotations

XML

Manifest Measurement

Data

XSD

XML Schema

SUPPORT

PRODUCT

PREVIEW

Data (e.g. img., param.)

Quicklook

Map

Preview

ANNOTATIONS

XML

Annotations Products metadata

Sentinels Core Products Products Format


Sentinel-3 Optical Sensors Products

OLCI, SLSTR, SYN


Sentinel-3 Core PDGS

L2 LAND / MARINE Production

L2 Optical production

organisation

Example of geophysical product: OLCI Terrestrial Chlorophyll Index (OTCI)

Chlorophyll Concentration for open ocean waters (CHL_OC4ME)

The Land and Water

masks are perfectly

complementary.

*The cloud mask is provided in white for a better interpretation

of the information.

Land products Marine products

The land and marine OLCI and SLSTR L2 products are processed taking into account the land/sea mask.

The L2 marine processing includes the open sea and the coastal area up to the coastline. The internal seas and lakes measurements are included in the marine product depending on the spatial resolution of the land mask.

The Level-2 marine products will have masked values for the pixels flagged as “land”, the Level-2 land products will have masked values for the pixels flagged as “water”.

NB : Water Vapour Products are processed over sea and over land with two different specific algorithms and then complementary merged to be identically contained in both marine and land products.


Optical Sensor: Level 2 Products – High Level


Optical Sensor: Sentinel-3 Core PDGS

Production

Δt = const.

Day/Night

border

frame

Day

Night

Δt = cost

Full swath

1269 kmBorder frame

~ 4

4 m

inute

s o

f data

Frames are identified by means of a fixed

reference system based on relative orbit

number within the cycle and on the granule

position along the orbit starting at ANX

The same relative orbit number and the same

frame position along the orbit is exactly

covering the same area within each cycle.

Full swath

1269 km

~ 4

4 m

inute

s s

trip

e

Spatial Sampling

Resolution:

1 km along and across

track at SSP

OLCI Reduced Resolution

data is provided in stripes.

OLCI L1B FR

Stripe Frame

OLCI L1B RR


User Products Size

Product Type Level Description Size (GB/orbit) Size frame / mn

OL_1_EFR___ 1 Full Resolution top

of atmosphere 27.900

0.634 1

1.268 2

1.9 3

3.17 5

OL_2_WFR___ 2

Full Resolution

Water &

atmosphere

parameters

33.40

OL_2_LFR___ 2

Full Resolution

Land and

Atmosphere

parameters

7.32

OL_1_ERR___ 1 Reduced Resolution

top of atmosphere 1.70

0.0386 1

0.0772 2

0.116 3

0.193 5

OL_2_WRR___ 2

Reduced Resolution

Water &

atmosphere

parameters

2.10

OL_2_LRR___ 2

Reduced Resolution

Land and

Atmosphere

parameters

0.50



L2 LAND / MARINE Production

PRODUCT TYPE LEVEL DESCRIPTION SIZE

(GBYTE/ORBIT)

SL_1_RBT___ 1

Brightness

temperatures and

radiances

45.60

SL_2_WST___ 2

Level 2P Sea

Surface

Temperature

(GHRSST like)

2.33

SL_2_LST___ 2

Land Surface

Temperature

Parameters

2.81

SLSTR User Products Size


SYN User Products Size

PRODUCT TYPE

LEVEL DESCRIPTION SIZE (GBYTE/ORBIT)

SY_2_SYN___ 2

Surface Reflectances and

Aerosol measurements

over Land

30

SY_2_VGP___ 2

1 km VEGETATION

Like product (~VGT-P) -

TOA Reflectances

1.21

SY_2_VG1___ 2

1 km VEGETATION

Like product (~VGT-S1)

1day synthesis surface

reflectances and NDVI

8

SY_2_V10___ 2

1 km VEGETATION

Like product (~VGT-

S10) 10days synthesis

surface reflectances and

NDVI

8



L2 LAND / MARINE Production Products Parameter : NETCDF

OL_1_FR and RR Ortho-geolocated TOA Radiance at 21 bands

OL_2_W_FR and RR Water leaving Reflectances Chlorophyll OC4Me Chlorophyll NN TSM_NN KD490 (Morel et al.) Absorption coefficient ADG_443_NN PAR AEROSOL – AOT at 865 and Angstrom WV

OL_2_L_FR and RR OGVI – FAPAR (rectified channels given in annotation) OCTI – Chlorophyll Terrestrial Index WV

SL_1_RBT Ortho-geolocated TOA radiances N/B view Brightness Temperature N/B View

SL_2_WST L2P

SL_2_LST LST

SY_2_SYN Surface reflectance in 30 bands in OLCI FR geometry AOT at 550 and Angstrom in OLCI FR geometry

SY_2_VGP TOA reflectance in 4 SPOT VGT bands at 1 km res.

SY-2_VG1/SY_2_V10 Daily/“ten days composite” fully atmosphere-corrected Surface Reflectance for SPOT channels. NDVI

Users Products Parameters


• The PDGS will produce also “internal Products” available for Cal/Val

activities only:

• L1C : SYN: OLCI + SLSTR Band in original geometry with

collocation information – Size estimated 56 GB / orbit. L1C is the

input for the L2 SYN branch.

• SST N2, D2, N3, D3. Intermediate products for SST final product

but not disseminated to users.

NB: Fire Radiative Power Product not in the current user product list.

Background and Framework Optical Sensor: Internal Products


Optical Sensors : Sentinel - 3 Core Products

Algorithms

NB: MEGS8 is the configuration for the MERIS 3rd reprocessing

OLCI Pixel classification - Richard Santer – MEGS8 OLCI Gas corrections, instrumental corrections and confidence check – FUB / ACRI / ARGANS MEGS8 OLCI Water vapour product FUB MEGS8 OLCI White caps & glint correction ARGANS OLCI Bright Water Atmospheric Correction Gerald Moore/Sam Lavander MEGS8 OLCI Standard Atmospheric Correction (SAC) over clear and turbid (bright) waters LOV MEGS8 OCLI Clear Waters Ocean Colour Products or CWOC Antoine/Morel LOV MEGS8 OLCI Ocean colour for clear and turbid waters plus transparency products GKSS (C2R) MEGS8 (from OLCI Alternative AC (AAC)) OLCI PAR (Photosynthetically Active Radiation) ARGANS OLCI Rayleigh Correction over land Richard Santer OLCI FAPAR (Fraction of Absorbed PAR) JRC MEGS8 OLCI OTCI (Terrestrial Chlorophyll Index) Univ. Of Southampton MEGS8 Adopted ATBD to be implemented over a longer timescale - TBC: OLCI ICOL - adjacency correction Richard Santer


SST ATBD

SLSTR SST (Sea Surface Temperature) including GHRSST L2P product Univ. Of. Edinburgh

SLSTR LST (Land Surface Temperature) NILU (Fred Prata) and Univ. Of Leicester

SLSTR FRP (Fire Radiative Power) KCL (not part of core product for time being)

SYNERGY / VGT ATBD

OLCI & SLSTR combined VGT and SYN products Swansea Univ.

Level 2 product DPM / IODD Detail Processing Model (DPM) / Input Output Data Definition:

OLCI – ACRI

SLSTR – RAL

Synergy – Brockmann Consult

Sentinel - 3 Core Products

Algorithms


QA4EO guidelines: Requirement: need to assign to all data / information products a Quality Indicator (QI), which allows

stakeholders to unequivocally evaluate the products’ suitability for a particular application.

For L2 OPT products, there are 21 ATBDs in total, which describe one or more algorithms including a

methodology to determine a quality indicator i.e. error/uncertainty estimate.

As the science is at different levels of maturity the proposed algorithms and quality indicators span a range

operational readiness.

Sentinel -3 Core PDGS products

QA4EO : Quality Indicators

Product Pixel by pixel error estimates Quality flag

Baseline - Water Leaving Reflectance Yes - ACRI Tech Note LUTs Yes - flag for quality of AC performed

Chlorophyll – OC4Me Not yet defined – Approach still

uncertain

Yes - if within pre-defined acceptable range

Ocean Colour NN outputs: CHL_NN; TSM_NN Yes - from a NNet to determine this. Yes - average difference between

observed and NNET forward derived reflectances

OLCI Global Vegetation Index FAPAR (OGVI)

and OLCI Chlorophyll Terrestrial Index (OCTI)

Not yet defined – Approach still

uncertain

yes

SST Yes Yes – exception flag

LST Yes Yes

Synergy products Yes propagates aerosol retrieval error

using L1c input error and RT

simulation error.

Yes


ALTIMETRY


20

Sentinel-3 STM Mission Heritage

2013: Sentinel-3

SRAL,

MWR,

POD 1992: ERS-1 1995: ERS-2

RA

1992: TOPEX /

Poseidon-1

Poseidon-1

2001: JASON-1

Poseidon-2

2002: ENVISAT

RA-2

SLSTR

OLCI

ATSR

AATSR

MERIS

1998: SPOT-4

Vegetation

2008: JASON-2

Poseidon-3

2010: CryoSat-2

SIRAL

2005: CryoSat-1

SIRAL

SARAL

2012:AltiKa


21

Sentinel-3 Orbit Characteristics

S-3 A & B STM Ground Tracks after 27 days of the first Sentinel-3 S/C

and of the second S/C in the baseline

configuration (180-deg spacing).

Inter-track distance at equator:

S-3A 104 km

S-3A & S-3B 52 km

Type Near-Polar Sun-Synchronous

Mean Local Solar Time at ascending node 22:00 h

Repeat Cycle 27 days

Cycle Length 385 orbits

Orbits per day 14.259

Semi-Major axis 7177.926540 Km

Eccentricity 0.001148

Inclination 98.645589º

Argument of Perigee 90º

Sentinel-3 Orbit characteristics

S-3 STM Orbit Characteristics

Topography Mission: - Ground track repeatability, - Dense spatial sampling Orbit control requirement: - Ground track dead-band +/- 1Km


22

Sentinel-3 STM

Topography Mission

S-3 STM Mission Mode Mask

Altimetry System

- Synthetic Aperture Radar

Altimeter (SRAL)

- MicroWave Radiometer

(MWR)

- GNSS

- DORIS

- LRR

Observed Surfaces

- Open ocean, coastal ocean

- Ice sheets (interiors and

margins)

- Sea ice

- In-land water (rivers & lakes)


Sentinel-3 SRAL: Open-loop Tracking Commands (OLTC)

OLTC is generated by ESA/CNES using a tool developed by CNES for Jason-2 and adapted for Sentinel-3.

A table stored on-board the SRAL, containing surface elevation information along the satellite track for the complete cycle (385 orbits), angular sampling: 0.01 degree (i.e. about 1 km)

DEM

Hydrology

database

Surface

mask OLTC

generation tool

Areas of interest


Sentinel-3 SRAL: Open-loop vs Closed-loop echo tracking

Closed loop tracking

Tracks echoes over most surfaces

No priority

– Land surface tracking instead of water surface

Sensitive to echo shape

– Loss of tracking

Acquisition Phase is needed

– At least 0.5s data gap

Tried and tested on many altimeter mission

Open loop tracking

Needs an accurate coding of surface elevation (accurate DEM, 1km) and Open Loop Tracking Commands

If a point of the surface is not properly coded in the OLTC, the echo is lost (no echo received on board)

Water Surface can be prioritized even over land surfaces

Altimeter always in tracking mode (+ for coastal area, sloppy terrain, and small Inland Water)

New approach with limited experience (Jason-2)


25

Level 2 Marine

products

EUMETSAT

Level 2 Land

products

ESA

Level 1

ESA/EUMETSAT

Coastal Zones Mask (<300km) and Land Mask

Measurements

included in the

LAND product

Measurements

included in the

MARINE

product

Land and Water masks are in overlap to

ensure analysis of transition and meaningful

continuity of segments

300Km over ocean – few km over land

LEVEL 1

- OLCI L1B

- SLSTR L1B

LEVEL 2

- OLCI L2 marine

- SLSTR L2 Marine

- SRAL L2 Marine

LEVEL 2

- OLCI L2 Land

- SLSTR L2 Land

- SYNERGY / VGT

- SRAL L2 Land

S-3 STM L2 production organisation

Sentinel-3 PDGS:

L1B & L2 Land / Marine Production

Marine product: information sensed over open ocean,

coastal areas, sea-ice + mask margin

Land product: information sensed over land, coastal areas,

land ice and inland water + mask margin

STM User Product

STM User Product


L1B MWR Product

26

Sentinel-3 STM:

L1B & L2 Processing Overview

SRAL Level 1B

Processor

MWR Level 1B

Processor

SRAL & MWR Level 2

Processor

Ku/C bands LRM mode SRAL

Measurement (20Hz)

Ku band SAR mode SRAL

Measurement (20Hz)

C band SAR mode SRAL

Measurement (20Hz)

MWR Measurements

(20Hz)

Ku/C bands LRM mode SRAL

Measurement (20Hz & 1Hz)

Ku band SAR mode SRAL


C band SAR mode SRAL


Auxiliary Data Files

CAL1 & CAL2 LTM

Files

Calibration &

Monitoring files

L0 SRAL Product



L1B SRAL Product L2 SRAL/MWR Product

L0 MWR Product

SRAL Level 0 Measurement

Data

SRAL Level 0 Calibration Data

MWR Level 0 Data


S-3 SRAL Products Levels

Product Type Product Level Description Distribution

SR_0_SRA___ 0 ISPs raw data (everything but calibration ISPs) Internal

SR_0_CAL___ 0 Calibration from SRAL ISPs Internal

SR_1_SRA___ 1 Echos for LRM and SAR mode Internal / CalVal user

SR_1_CAL___ 1 Level 1 SRAL calibration parameters Internal / CalVal user

SR_2_LAN___ 2 1-Hz and 20-Hz Ku and C bands parameters (LRM/SAR),

waveforms. Over Land

User / CalVal user

SR_2_WAT___ 2 1-Hz and 20-Hz Ku and C bands parameters (LRM/SAR),

waveforms. Over Water

User / CalVal user

S-3 MWR Products Levels

MW_0_MWR__

_

0 Observation, calibration and monitoring parameters from

MWR ISPs

Internal

MW_1_MWR__

_

1 Level 1 observation data Internal / CalVal user

MW_1_CAL___ 1 Level 1 calibration and monitoring MWR data Internal / CalVal user

S-3 GNSS Products Levels

GN_0_GNS___ 0 GNSS ISP Internal

GN_1_GNS___ 1 Rinex Internal / CalVal user

S-3 DORIS Products Levels

DO_0_DOP___ 0 Measurements packets including Doppler, datation and test

packets

Internal

DO_0_NAV___ 0 Navigation packets including ITRF, geodetic and J2000 Internal

DO_1_DOP__ 1 DORIS Level 1B Internal / CalVal user

27

Sentinel-3 STM: PDGS Product List

STM

User Products

S-3 STM PDGS product list


Sentinel-3 STM: Products Timeliness

28

time 3 h 2-3 d ~30 d ~1/2 y

NRT products

STC products

NTC products

NTC products

Reprocessing Campaign

NRT: Near Real time

STC: Slow Time Critical

NTC: Non time Critical

Ocean forecasting,

Meteorology, Oceanography

Operational Ocean,

Ocean forecasting,

Oceanography

Climatology,

Oceanography,

Data exploitation

T0 Sensing time


29

Sentinel-3 STM: Products Types

20HzCbandparametersfromSRALmeasurementsperformed

inLRM/SARModes

waveforms and associated

parameters to reprocess the

data

(at least in LRM)

20 Hz LRM/SAR_C Data Set

Waveforms

“Enhanced” Measurement Data File

“Standard” Measurement Data File

“Reduced” Measurement Data File

Sub-setof1HzKu/CbandparametersfromSRAL

measurementsperformedinLRM/SARModes

1 Hz LRM/SAR Ku/C Data Set

1HzKu/CbandparametersfromSRALmeasurementsperformed

inLRM/SARModes


20HzKubandparametersfromSRALmeasurementsperformed

inLRM/SARModes

20 Hz LRM/SAR_Ku Data Set

20HzCbandparametersfromSRALmeasurementsperformed

inLRM/SARModes

20 Hz LRM/SAR_C Data Set

1HzKu/CbandparametersfromSRALmeasurementsperformed

inLRM/SARModes


20HzKubandparametersfromSRALmeasurementsperformed

inLRM/SARModes

20 Hz LRM/SAR_Ku Data Set

“Enhanced” Measurement Data File

“Standard” Measurement Data File

“Reduced” Measurement Data File

1Hz

1Hz + 20 Hz 1Hz + 20 Hz +

WF


30

Algorithm heritage from ERS-1, T/P, ERS-2, Jason-1, Envisat, Cryosat, Jason-2

Retrackers run in parallel in LRM and SAR mode

• MLE4 Ocean LRM mode (OCE_01) Ku/C bands

• SAMOSA Ocean SAR mode (OCE_02) Ku band

• OCOG Ice LRM/SAR mode (ICE_01) Ku/C bands

• MLE4 Ice Sheet LRM mode (ICE_04) Ku/C bands

• Ice-margin SAR mode (ICE_05) Ku band

• Ice (erf) LRM (ICE_02) Ku/C bands

• Sea-ice SAR mode (ICE_03) Ku band

Standard geophysical corrections/fields + …

• Sea-ice freeboard, new coastal composite and open ocean (using SST) wet tropospheric

corrections, distance to the coast, enhanced 6-states sea-ice flag, continental ice

classification, 6-states rain flag, …

State-of-the-art SAD & DAD files harmonized (where possible) with other

operational missions

• 2D & 3D ECMWF fields for wet and dry model corrections, 2 MSS, MDT, …

Sentinel -3 STM: Algorithms &

Products Content

MARINE & LAND L2 STM products WILL have the same Processing Baseline


Sentinels Core Products Products Volume

SRAL+MWR Data

Product Type Data volume

(GByte/orbit)

Data volume

per day

(GByte)

Data volume

per week

(GByte)

Data volume

per year

(TByte)

SR_0_SRA___ 5.82 82.98 580.87 29.58

MW_0_MWR___ 0.003 0.04 0.28 0.014

MW_1_MWR___ 0.003 0.04 0.28 0.014

SR_1_SRA___ 0.12 1.65 11.54 0.59

SR_2_WAT___ 0.09 1.31 9.16 0.47

SR_2_LAN___ 0.07 1.00 7.01 0.36

TOTAL 6.10 87.02 609.13 31.02

S-3 STM Level 2 product volume:

Reduced 0.52 MB / orbit Standard 32 MB / orbit Enhanced 112 MB / orbit

< 1 Tbyte / year for the overall S-3 STM L2 user data set


• Altimetry core products Processing Baseline V1 completed

• V2 processing baseline planned for Q2 2012

• SAMOSA ocean SAR retracker implementation

• Inclusion/update of SAD files

• Intended alignment of the Envisat Altimetry processing chain (where possible)

• Core Products definition largely based on ENVISAT/VGT continuity

• Most of OLCI L2 algorithm have been implemented in MERIS for the 3rd reprocessing

(MEGS8)

• L1 & L2 algorithms : Detailed Processing Models and test data generation under completion

• Operational processors and operational quality control support functions procurements

scheduled for kick-off respectively in Q2 & Q4 2012.

• Reference test data and documentation available to users for prototyping in 2012 or early

2013

• Atmospheric products under discussion via users e.g. EUMETSAT Science Working Group

• Meeting between ESA/EUMETSAT/ECMWF (MACC) took place in October 2011 to identify

MACC need in term of atmospheric products. Requirements need to be received and

analyzed.

Conclusion: Sentinel -3 Core products

Implementation Plans and Status