CCVS workshop Fiducial Reference Measurements for SST: progress and challenges - Anne O'Carroll (EUMETSAT) Marc Lucas (CLS)
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copernicus.eumetsat.int CCVS workshop Fiducial Reference Measurements for SST: progress and challenges Anne O’Carroll (EUMETSAT) Marc Lucas (CLS) 9th May 2022 EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 1
Outline
copernicus.eumetsat.int
Progress so far
• Background
• Introducing TRUSTED
Current and short-term activities
• Continuation of FRM buoys
• International coordination
• Quality Control, Metadata, FRM
• Sea-ice buoy design and prototype
Future plans
• EUMETSAT plans and needs
• Fiducial Reference Measurements for the
Copernicus programme
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 2
Copernicus Sentinel-3 SLSTR Sea Surface Temperature
copernicus.eumetsat.int
• Sentinel-3A launched 16 February 2016
• Sentinel-3B launched 25 April 2018
• Sea Surface Temperature (SST) observed from:
Sea and Land Surface Temperature Radiometer
(SLSTR)
• Highly accurate measurements providing a
reference dataset and time-series for other SST
missions
• Dual-view SST for better atmospheric correction and
highly accurate Sea Surface Temperature
• Two on-board black-body calibration sources
• Continuation of climate SST time-series from (A)ATSR
series of instruments
• More info: www.eumetsat.int/SLSTR
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 3
Satellite Sea Surface Temperature validation
copernicus.eumetsat.int
Reference data, such as drifting buoys, are essential for
satellite SST validation
Global Drifter Programme array 4th May 2022
Validation activities crucial to assessing and maintaining https://www.aoml.noaa.gov/phod/gdp/interactiv
SLSTR SST product quality e/drifter_array.html
• Collocations with drifting buoy SST
• Inter-comparisons with other satellite SST
• Collocations with Fiducial Reference Measurements
(e.g. radiometers, reference drifting buoys)
Matchup database (MDB) with Sentinel-3 SLSTR Sea
Surface Temperature available on request from
EUMETSAT
Key activity in Sentinel-3 Calibration and
Validation plan
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 4
DBCP-GHRSST Pilot Project
copernicus.eumetsat.int
• Original proposal in 2013 requested:
• A number of drifters to be upgraded to a higher specification
• Position accuracy and reporting to 0.01degrees (HRSST-1)
• SST accuracy < 0.05K; reporting to 0.01K (HRSST-2)
• ->Total standard uncertainty in measured SST to be < 0.05K
• Requirements (e.g. Blouch, DBCP-29)
• Hourly measurements
• Report design depth in calm water to ±5cm
• Report of geographical location to ±0.5km or better
• Report of time of SST measurements to ±5 minutes
• Endorsed by GHRSST 2013; Sentinel-3 Validation team 2013; and
discussed at CEOS WGCV
• Recent work considering and building on recommendations from
ESA FRM4STS project on non-recoverable buoys
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 5
TRUSTED overview
copernicus.eumetsat.int
• Towards Fiducial Reference Measurements from drifting buoys for
Copernicus satellite validation,TRUSTED (2018-2021)
• Main achievements:
• 150 SVP-BRST (HRSST-2) drifters and measurements
• Two high quality SST sensors; temperature depth; high-frequency data
• Calibration per sensor
• Improvements towards metadata access and storage
• Stability analysis: BSH; AMT experiment
• Review workshop, March 2021, https://www.cls-temetry.com/workshop-high-
resolution-sea-surface-temperature-hrsst-drifting-buoys-for-satellite-sst/
• Lucas et al, https://www.eumetsat.int/media/48922
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 6
SVP-BRST design (NKE)
copernicus.eumetsat.int
Positioning
Positioning refresh
GPS
Design based on the SVP-B: HRSST
SST
• DBCP compliant Calculation of
Barometer
Submergence
Next Date/Time
• 4 sensors: P, SST, HRSST, HP
acquisition (Tacq) Iridium
session
t
• GNSS positioning Delays of anticipation depend of
sample number and sampling
period of each sensor
Tacq
Tacq
+ 30s
SBD message
creation
• Iridium modem
+
Calculation of next
date/time acq
Tacq – 15mn Tacq - « [GPS]-P9 »
SC40 SVP-BRST – Acquisition description
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 7
Metrology and Calibration (SHOM)
copernicus.eumetsat.int
• TRUSTED buoys are calibrated at the SHOM
metrology laboratory for temperature (Marc Le
Menn)
• ‘MoSens’ module contains the HRSST sensor
and are calibrated before integrations in
batches of 10
• The graph show the residuals of the calibration
in green and the deviations obtained after the
verification of coefficients (in blue), by
measurements in the bath
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 8
World wide deployments (Meteo-France)
copernicus.eumetsat.int
• 152 buoys deployed to date:
• 138 low frequency (LF) buoys deployed
• Mean and percentiles
• 14 high frequency (HF) buoys deployed
• 300 data points over 5 minutes
• longest deployment: 720 days
• Maximum of 70 at sea simultaneously
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 9
Post deployment Calibration (SHOM)
copernicus.eumetsat.int
• 3 buoys recovered so far:
• 1 onshore Iceland (damaged)
• 1 east of Iceland ( intact)
• 1 moored in the North Sea (BSH)
Tref standard uncertainty : 0.001 °C
Bath stability standard uncertainty : : 0.000 °C
Reproducibility buoy n° 025 : 0.006 °C
Repeatability buoy n° 025 : 0.001 °C
Verification expanded uncertainty: 0.012 °C
Tref standard uncertainty : 0.001 °C
Bath stability standard uncertainty : : 0.000 °C
Reproducibility buoy n° 017 : 0.005 °C
Repeatability buoy n° 017 : 0.001 °C
Verification expanded uncertainty: 0.011 °C
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 10AMT sensor comparison (W.Wimmer)
copernicus.eumetsat.int
• Tank on scientific flow through system
• HART 1504 with Thermometric 225
• HRSST drifter probe 1
• HRSST drifter probe 2
• NOSS sensor
• Thermistor
• Data logged every second from 18/10
to 22/11/2019
• Excellent stability over Temperature
range and duration
• Sensor uncertainty close to that of
reference probe
• Mean diff 2.5mK, Stdev 3.7mK
• Sensor to sensor variation
• Mean diff 1.1mK, Stdev 2.0mK
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 11International coordination and definitions
copernicus.eumetsat.int
• Participation and coordination with WMO Data Buoy Cooperation
Panel (DBCP) and Global Drifter Programme (GDP)
• Coordination with Sentinel-3 validation team and GHRSST HRSST
Task Team
• Two definitions for HRSST-2 and FRM drifters presented to DBCP-37
(https://www.eumetsat.int/media/48924):
• HRSST-2 Original DBCP/GHRSST specification plus machine searchable /
accessible global metadata information (in progress with OceanOps)
• FRM for drifters
• Calibration per sensor in laboratory independent of sensor
manufacture
• Definition of uncertainty budget / traceability diagram
• Measurement metadata and improved Quality Control
• Coordination with National Metrology Institutes
• Post-deployment calibration and analysis where opportunity
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 12Validation and assessment
copernicus.eumetsat.int
• Validation with SLSTR SST at EUMETSAT
• SLSTR and TRUSTED MDB available for
sharing (Igor Tomazic)
• GHRSST Task Team on HRSST (Gary
Corlett)
• Coordination with GDP, DBCP and OceanOps
• Most drifting buoy data are now HRSST-2
• Use TRUSTED / FRM data to develop a ‘self-
QC’ methodology and apply a TRUSTED
method to all HRSST drifters
• Further validation needed and exploitation of
MDB and new data https://s3calval.eumetsat.int/ma/sst/trusted/
• Need for robust online searchable metadata Corlett et al, 2022, DBCP-37
(https://www.eumetsat.int/media/48923)
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 13TRUSTED continuation (2022-2024)
copernicus.eumetsat.int
• Recommendations from 2021 HRSST TRUSTED
workshop
https://www.cls-temetry.com/workshop-high-resolution-
sea-surface-temperature-hrsst-drifting-buoys-for-satellite-
sst/
• Main objectives:
• Continuation of SVP-BRST drifters (25 per
year) with focus at high-latitudes
• Specification of full QC procedure and
definition for route to FRM
• Endorsement of FRM SST/sea-IST with peer
review including a full uncertainty and
traceability model
• Design, prototype and deploy sea-ice buoys
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 14Metrology and traceability diagrams (SHOM)
copernicus.eumetsat.int
Calibration Air temperature Water temperature
Linearity Repeatability Reproducibility
Buoy influence Sun radiation
Tref uncertainty MoSens drift
MoSens calibration 1 buoy HRSST n buoys HRSST
uncertainty uncertainty uncertainties
Bath Response
stability/ho Immersion time Measurement depth
mogeneity depth
Sea
Sea state stratification
TRUSTED
Wind
• Coordination with European Metrology Satellite Temperature
Network temperature
uncertainty
validation
uncertainty
• Activities beginning towards a traceability
diagram for TRUSTED drifting buoys
• Uncertainty model per buoy
• Inclusion of link from in situ to satellite
measurement component
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 15Metadata (OceanOps)
copernicus.eumetsat.int
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 16Sea-ice buoy design and prototype (DMI)
copernicus.eumetsat.int
• Operational Sentinel-3 SLSTR sea-ice Surface
Temperature products planned for 2024 (demo
products available on WEkEO on request)
• Poor coverage of IST in situ observations in the
high-latitudes limits the satellite IST algorithm
development and validation
• Difficult to assign model analysis errors
• Therefore, design and prototype in progress to
provide Copernicus FRM over sea-ice
• Aim to better represent the snow-skin/ice
surface temperature
• Need a high-quality, easy to deploy, sea-ice
drifter in larger numbers
• Challenges: large vertical gradients, large diurnal
variability
• Coordination with International Arctic Buoy
Programme (IABP) and DBCP
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 17The future needs for SST FRM
copernicus.eumetsat.int
• Copernicus Sentinel-3 Sea Surface Temperature validation requires a sub-set of
extremely high quality Fiducial Reference Measurements
• Traceability for climate data records -> understand how accurate products
really are and to deliver the required confidence e.g. GEO/CEOS QA4EO
• Long-term investment -> balanced to deliver a satellite mission with a known
product quality that is fit for purpose
• Global coordination increases quality in whole network -> beneficial for both
satellite and ground based users
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 18Copernicus plans at EUMETSAT SST FRM (2022-2025)
copernicus.eumetsat.int
• Copernicus supports a further extension for a limited set of buoys
• This includes the new development of sea-ice buoys
• Coordination internationally with WMO and DBCP
• Towards searchable, global and measurement metadata
• Revise / propose specifications for HRSST and FRM
• Coordination with NOAA and Global Drifter Programme on HRSST for satellite SST
validation
• Assessment of current drifters
• Propose uncertainty model for drifters
• Define a protocol for real-time Quality Control of drifting buoys
• EUMETSAT / Copernicus cannot finance beyond development and specific limited
deployments, and that reliability has to come from Member States and internationally
through EUMETNET and WMO.
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 19Summary
copernicus.eumetsat.int
Activities so far:
• Background satellite Sea Surface Temperature validation
• Towards Fiducial Reference Measurements (FRM) for European drifters
(TRUSTED) project
• 150 buoys providing measurements for Sentinel-3 Sea Surface Temperature validation
• Design of new SVP-BRST platform
• Rigorous metrology practises
• Collection and archiving of all relevant metadata
Next 3 years:
• Continuation of buoy deployments and measurements (further 75)
• Further definition of QC procedures and metadata storage and retrieval
• FRM standard for drifters in coordination with National Metrology Institutes
• Design and prototype of new sea-ice drifter for snow and ice surface
temperature
Future plans
• EUMETSAT plans and needs
• Fiducial Reference Measurements for the Copernicus programme
https://www.eumetsat.int/TRUSTED
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 20copernicus.eumetsat.int
Acknowledgements
Gary Corlett, Igor Tomazic, Marc Le Menn, Arnaud David, Jerome Sagot,
Mathieu Belbeoch, Long Jiang, Christophe Quillerm, Olivier Desprez de
Gesincourt, Kai Herklotz, Gorm Dybkjaer, Jacob Hoeyer, Werenfrid Wimmer
Publications
Le Menn M., et al, 2019, Development of Surface Drifting Buoys for
Fiducial Reference Measurements of Sea-Surface Temperature, Frontiers
in Marine Science,6, https://doi.org/10.3389/fmars.2019.00578
Poli P., et al, 2019, The Copernicus Surface Velocity Platform drifter with
Barometer and Reference Sensor for Temperature (SVP-BRST): genesis,
design and initial results, Ocean, Sci., 15, 199
214, https://doi.org/10.5194/os-15-199-2019
Thank you!
Questions are welcome.
Anne.OCarroll@eumetsat.int
mlucas@groupcls.com
EUM/OPS-COPER/VWG/22/1303802, v1, 4 May 2022 21You can also read
