Gap-free SST analyses using satellite, and possibly in situ data, are the most widely used SST products for both operational and research applications. Currently more than thirty level 4 (L4) near real-time and reprocessed SST analyses are publicly available from organisations and operational agencies.
OBJECTIVES
Compare the SST analyses and validation of the analyses, in order to provide information to producers to enable them to improve their analysis systems and to provide guidance to users in their particular applications.
ONGOING ACTIVITIES
The core activity of the Climatology and L4 Inter-Comparison Task Team is to compare features in different L4 products. The work is further divided into the following sub-tasks.
Task 1 – Validate L2, L3, and L4 SST gradients in highly variable regions using SailDrone and/or ship SST
Task Lead: Jorge Vazquez (NASA/JPL)
Task Description: An investigation examining SST gradients in SST analyses. SST gradients in L2, L3, and L4 SST products in highly variable regions are validated using SailDrone data.
Outputs and Results
- Eight SailDrone deployments of the USA West Coast to validate Modis L2 and MUR L4 SST at 1km resolution
- Better accuracies for the MUR products
- Demonstrated the ability of the SailDrones to accurately validate near-shore satellite SST products and provide
- Vazquez-Cuervo, J.; Gomez-Valdes, J.; Bouali, M.; Miranda, L.E.; Van der Stocken, T.; Tang, W.; Gentemann, C. Using Saildrones to Validate Satellite-Derived Sea Surface Salinity and Sea Surface Temperature along the California/Baja Coast. Remote Sens. 2019, 11, 1964. https://doi.org/10.3390/rs11171964
- Vazquez-Cuervo, J.; Castro, S.L.; Steele, M.; Gentemann, C.; Gomez-Valdes, J.; Tang, W. Comparison of GHRSST SST Analysis in the Arctic Ocean and Alaskan Coastal Waters Using Saildrones. Remote Sens. 2022, 14, 692. https://doi.org/10.3390/rs14030692
- Vazquez-Cuervo, J.; García-Reyes, M.; Gómez-Valdés, J. Identification of Sea Surface Temperature and Sea Surface Salinity Fronts along the California Coast: Application Using Saildrone and Satellite Derived Products. Remote Sens. 2023, 15, 484. https://doi.org/10.3390/rs15020484
- Koutantou, K.; Brunner, P.; Vazquez-Cuervo, J. Validation of NASA Sea Surface Temperature Satellite Products Using Saildrone Data. Remote Sens. 2023, 15, 2277. https://doi.org/10.3390/rs15092277
Task 2 – Produce online visualisation tool for L4 SST fronts
Task Leads: Prasanjit Dash (NOAA),Marouan Bouali (ORTBY Ltd.)
Task Description: An online visualisation tool for L4 SST gradients has been deployed in the NOAA OceanView (OV) system (https://www.star.nesdis.noaa.gov/socd/ov/), and a visualisation tool for marine heatwaves is in development. OV displays the location of SST fronts derived from NOAA/SOCD Geo-Polar blended Level 4 SST, according to user specifications. Characteristics of detected fronts such as average SST gradient magnitude and length are available and can be used to filter the displayed fronts. OV also includes a profiler to see the value of SST gradients along a given front.
Outputs and Results
- https://www.star.nesdis.noaa.gov/socd/ov/
Task 3 – Develop the science to calculate SST/SST fronts and inter-compare
Task Leads: Daniele Ciani (CNR-ISMAR), Mattia Sabatini (CNR-ISMAR)
Task Description: Generation of L4 SST datasets from the combination of IR and Microwave SST in the Mediterranean Region. This is based on numerical model outputs and part of the science studies for the ESA-Copernicus Imaging Microwave Radiometer Mission.
Outputs and Results
Numerical studies on the generation of L4 SST datasets from the combination of IR and Microwave SST in the Mediterranean Region are underway and they are part of a publication currently in preparation:
- Impact of the Copernicus Imaging Microwave Radiometer Mission on the Mediterranean Sea Surface Temperature L4 Analyses: Preliminary Study (Sabatini et al., in prep)
The inter-comparison of UKMO OSTIA NRT/REP L4 SSTs for ocean surface currents reconstruction (uptake from ESA-World Ocean Circulation project) has been finished. Results have been published in the following paper:
- Ciani, D.; Asdar, S.; Buongiorno Nardelli, B. Improved Surface Currents from Altimeter-Derived and Sea Surface Temperature Observations: Application to the North Atlantic Ocean. Remote Sens. 2024, 16, 640. https://doi.org/10.3390/rs16040640
The task on the computation of SST gradients from the future ESA-Earth Explorer 10 Harmony mission has been finished and results have been published in the following paper (potentially, this task will have a follow-up in the period 2025-2027)
- Ciani, D.; Sabatini, M.; Buongiorno Nardelli, B.; Lopez Dekker, P.; Rommen, B.; Wethey, D.S.; Yang, C.; Liberti, G.L. Sea Surface Temperature Gradients Estimation Using Top-of-Atmosphere Observations from the ESA Earth Explorer 10 Harmony Mission: Preliminary Studies. Remote Sens. 2023, 15, 1163. https://doi.org/ 10.3390/rs15041163
Task 4 – Validate SST gradients/fronts with other independent but related data
Task Leads: David Wethey (University of South Carolina), Nico Weidberg (University of South Carolina), and Jorge Vazquez (NASA/JPL)
Task Description: Aim to validate SST gradients/fronts with other independent but related data (e.g., sea surface salinity gradients or altimeter-derived currents), using OceanView.
Outputs and Results
- Weidberg, N.; Wethey, D.S.; Woodin, S.A. Global Intercomparison of Hyper-Resolution ECOSTRESS Coastal Sea Surface Temperature Measurements from the Space Station with VIIRS-N20. Remote Sens. 2021, 13, 5021. https://doi.org/10.3390/rs13245021
Task 5/6 – Compare feature resolution and spatial consistency of various L4 products across different marine regions; Compare SST gradients over seasonal and interannual time scales for various high-resolution L4 products
Task Leads: Davide Cavaliere (CNR-ISMAR), Daniele Ciani (CNR-ISMAR), Chunxue Yang (CNR-ISMAR), Cristina Gonzalez-Haro (ICM-CSIC), Salvatore Marullo (CNR-ISMAR)
Task Description: Explore methodologies other than spectral analysis to define a “resolution” metric in the spatial domain.
Outputs and Results
- ECOSTRESS SST gradient validation using Saildrones and ships (IMOS and ships4sst)
- Incorporation of ECOSTRESS SST into OceanView
- Compare SST gradients over seasonal and interannual time scales for various high-resolution L4 products
Task 7 – SST fronts and Ocean Color Fronts
Task Leads: Prasanjit Dash (NOAA), Marouan Bouali (Orbty Ltd.), Jishad M. (ISRO), Neeraj Agarwal (ISRO)
Task Description: Focuses on the detection of ocean front in SST and Ocean Color datasets. It also includes data fusion studies to improve the quality of satellite-deirved Ocean Colour front estimates.
COMPLETED ACTIVITIES & RESULTS
Task 1 – Inter-comparison of SST analyses for climate (Lead: Chunxue Yang, CNR-ISMAR)
The IC TT inter-compared SST analyses for climate studies (analyses of at least 15 years duration) in the framework of the Copernicus Climate Change Service (C3S). The work was led by Chunxue Yang, CNR/ISMAR.
- The results of the study have been published in the Journal of Climate for peer review and publication: Yang, Chunxue, Francesca Elisa Leonelli, Salvatore Marullo, Vincenzo Artale, Helen Beggs, Bruno Buongiorno Nardelli, Toshio Michael Chin,
- Vincenzo De Toma, Simon Good, Boyin Huang, Christopher J. Merchant, Toshiyuki Sakurai, Rosalia Santoleri, Jorge Vazquez-Cuervo, Huai-Min Zhang, Andrea Pisano (2020) Sea Surface Temperature intercomparison in the framework of the Copernicus Climate Change Service (C3S), J. Climate, https://doi.org/10.1175/JCLI-D-20-0793.1
- Preliminary results were reported to the GHRSST-XXI Science Team Meeting in 2020 (view the presentation here)
- Final report to the Science Team was presented at GHRSST XXII Science Team Meeting in 2021 (view the presentation here).
Task 1 contributed to the Independent Assessment of Essential Climate Variables (C3S_511) Project for the Copernicus Climate Change Service (C3S). The C3S_511 Project closed 30 June 2021. Plans for intercomparison activities under the next phase of C3S are to be determined.
Task 2 – Understanding the differences between SST analysis systems (Lead: Xu Li, NOAA/NCEP)
The number of drifting buoy observations used in an SST analysis system depends on many factors such as Quality Control, observation error, weighting relative to the background, and correlation length scale. The observation counts are system dependent even if the data received by the systems are the same. Results of a short study on the availability of drifting buoy observations in various operational SST analyses led by Xu Li (NOAA/NCEP) were presented in the Task Team session at the GHRSST-XXI Meeting (view the presentation here). The study compared four global SST analysis systems (NOAA/NCEP NSST, ECCC CMC 0.1 degree, ABoM GAMSSA and UKMO OSTIA) The numbers, total and used, of drifting buoy observations based on the 10-day daily average for 1-10 May 2020 were examined. As expected, the total number of drifting buoy observations ingested is different for each L4 product due to different quality control, data time windows, start times and cut-off times. CMC is the only L4 system to choose only one report per platform per day. GAMSSA is the only system to reject in situ data suspected of experiencing a diurnal signal.
The way in situ data are used in operational L4 systems (directly assimilated, quality control or bias correction of satellite data, etc.) is being investigated. The study will examine the impact of ingesting BUFR format ship SST data from the GTS and the impact of COVID-19 on the total number and type of in situ data ingested into operational SST analysis systems. Results will be reported to the Science Team at the GHRSST-XXII Science Team Meeting (2021).
If interested in knowing more about this task, please contact Xu Li: xu.li@noaa.gov.
LAST REPORTS TO THE SCIENCE TEAM
- June 2024: Presentation: https://zenodo.org/records/13692343 and recording: Task Team 2024 SST Climatology and L4 Intercomparison
- October 2023: Presentation https://zenodo.org/records/10044527 and recording: Task Team 2023: Climatology and L4 Inter-Comparison – YouTube
- June 2022: Presentation: Updated presentation (Version 30 June 2022) and previous presentation (Climatology and L4 Inter-Comparison). Recording: https://vimeo.com/727700672 Start from minute 16:55
- June 2021: SST Climatology and Analysis Inter-Comparison Task Team Report 2021 by Beggs, Helen, Chunxue Yang, Jorge Vazquez, Prasanjit Dash, Marouan Bouali, Xu Li and the IC Task Team. Presented at the 22nd GHRSST Science Team Meeting, 7-11 June 2021. Slides on progress, June 2021: Slides-IC2021
- June 2020: SST Climatology and Analysis Inter-Comparison Task Team Report 2020 by Beggs, Helen, Chunxue Yang, Vincenzo Artale, Bruno Buongiorno Nardelli, Vincenzo De Toma, Francesca Elisa Leonelli, Salvatore Marullo, Andrea Pisano, Rosalia Santoleri, Xu Li, Boyin Huang, Prasanjit Dash, Jorge Vazquez, Simon Good, Chongyuan Mao and the IC Task Team. Presented at the 21st GHRSST Science Team Meeting, 1– 4 June 2020
TASK TEAM MEMBERS
Co-Chairs: Daniele Ciani (CNR-ISMAR) and Jorge Vazquez (JPL/NASA)
Members: Neeraj Agarwal (ISRO, India), Sheekela Baker-Yeboah, (NOAA, USA), Helen Beggs (BOM, Australia), Marouan Bouali (ORBTY Ltda., Brazil), Davide Cavaliere (CNR-ISMAR, IT), Prasanjit Dash (NOAA, USA), Toshio M. Chin (JPL, USA), Owen Embury (U. Reading, UK), Cristina Gonzalez Haro (ICM-CSIC, Spain), Pallavi Govekar (BOM, Australia), Andy Harris (NOAA, USA), Ioanna Karagali (DMI, Denmark), Andrea Massi (CNR-ISMAR, IT), Chongyuan Mao (Met Office, UK), Jishad M. (ISRO, India), Kyung-Ae Park (Seoul University, KR), Salvatore Marullo (CNR-ISMAR, IT), Mattia Sabatini (CNR-ISMAR, IT), Rosalia Santoleri (CNR-ISMAR, IT), Dorina Surcel-Colan (ECCC, Canada), Nico Weidberg (Uni. Oviedo, Spain), David S. Wethey (Uni.South Carolina, USA), Christo Whittle (CSIR, South Africa), Gary Wick (NOAA, USA), Chunxue Yang (CNR-ISMAR), Xungang Yin (NOAA, USA), Huai-min Zhang, (NOAA, USA)
INTERESTED IN CONTRIBUTING?
Please contact the co-chairs or the task leaders directly:
- Daniele Ciani, daniele.ciani@cnr.it
- Jorge Vazquez, jorge.vazquez@jpl.nasa.gov