Workshop on observations and analysis of sea-surface temperature and sea ice for NWP and Climate Applications

ECMWF | Reading | 22-25 January 2018

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Workshop Announcement

An accurate characterisation of the ocean in terms of its surface temperature and sea ice coverage is vital for Numerical Weather Prediction (NWP) forecasts a few days in advance out to the seasonal range. This workshop was organised to bring together experts involved in all aspects of this field, including the treatment of ocean surface observations (both satellite and in situ), data assimilation techniques and modelling. Three days of presentations was followed by working group meetings which assessed the current state of the art and identify areas where significant improvements and progress can be made.


A key part of the ECMWF new strategy is to develop an Earth-system analysis and forecast system, and to introduce more coupling in data assimilation and the forecasting model since this could be the best way to extract predictable signals from the initial conditions, and thus improve the quality of our forecasts. This will imply further developing the ECMWF prototype coupled assimilation that has been used to generate the first European coupled reanalysis of the 20th century. ECMWF new ocean reanalysis/analysis ORAS5, at a 1⁄4 degree resolution and with 75 layers, includes also the sea-ice. In Q4-2016, ECMWF  introduced an interactive sea-ice in its medium-range/monthly ensemble (ENS). The development of an ECMWF’s own sea-surface temperature (SST) data assimilation capability could be another necessary step to move towards better initial conditions for the coupled model, and to develop a ‘stronger’ coupled data assimilation. This workshop gave us the opportunity to discuss with experts from the international community how best to proceed in this area.


The landscape of users and applications of Sea Surface Temperature (SST) and Sea Ice (SI) information has changed considerably in the past few years. Observations, applications and methodologies are undergoing a major shift. In the case of SST and SI, the paradigm of Earth System Forecasting systems has brought together activities and communities traditionally separated, such as the weather and marine communities, and the weather and climate. There is a pressing need to revisit the current practices in view of new potential and current deficiencies, to provide guidelines for future directions and to prepare the ground for institutional collaboration at international level.


The workshop took place at ECMWF on 22 - 25 January 2018. It revolved around four central themes:

Session 1: Observations of the SST and SeaIce: overview of observations of SST and sea ice. Remote sensed and in-situ. Past-Present-Future.

Session 2: Processing chains: retrievals, gap filling and product delivery.

Session 3: Applications: defining the observational requirements.

Session 4: New methods.

Working Groups

WG1: Observations and Methods processing chains - Frozen (Sea Ice)

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WG2: Downstream applications of SST and Sea Ice

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WP3: Observations and Methods processing chains - Unfrozen (SST)

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Workshop report

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Some questions were addressed:

  • Which level of information should be assimilated in NWP for timeliness?
  • Which level of information should be used in reanalyses? How to guarantee consistency between reanalyses and real time?
  • Are the required data streams in place? how to avoid duplication?
  • How to manage different spatial scales?
  • How to manage temporal evolution (stability, bias correction, merging old and new methods, timeliness).
  • Which other observations should be used?
  • Which developments in data assimilation methods are needed?
  • Which developments in forward modelling are needed?


Monday 22 January

Quantifying the thermodynamic state of the global ocean surface
Chris Merchant (University of Reading)

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Satellite Sea Surface Temperature – current and future observations at ESA
Craig Donlon (ESA)

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Observations of sea-surface temperature made in situ: evolution, uncertainties and considerations on their use
Nick Rayner (Met Office)

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Satellite observations of sea ice concentration and drift
Leif T. Pedersen (Technical University of Denmark)
Presented by Rasmus Tonboe (DMI)

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In-situ and airborne sea ice observations for better sea ice prediction and climate analysis
Christian Haas (AWI)

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Future ESA satellite missions to observe the ocean and ice surface
Mark Drinkwater (ESA)

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Tuesday 23 January

Copernicus Sentinel-3 L1 to L4 SST processing chain and GHRSST perspectives
Anne O'Carrol (EUMETSAT)
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From L1 to L2 SST: signal/errors and gaps
Hervé Roquet (Météo-France)
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From L1 to L2 for sea ice concentration
Rasmus Tonboe (DMI)
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Sea ice charts and SAR for sea ice classification
Patrick Eriksson (FMI)
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The Operational Sea Surface Temperature and Ice Analysis (OSTIA) system
Simon Good (Met Office)
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Reanalysis needs for observations and analyses of sea surface temperature and sea ice: atmospheric perspective
Adrian Simmons (ECMWF)
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Climate reanalysis and reforecast needs: An ocean perspective
Hao Zuo (ECMWF)
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NWP needs and gaps
Kristian Mogensen (ECMWF)
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Use of Sea Surface Temperature and Sea Ice observations for the Copernicus Marine Service and its applications
Antonio Reppucci (Mercator-Ocean)
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Ocean data assimilation systems in JMA and their representation of SST and sea ice fields
Yosuke Fujii (JMA)
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The CERA-SAT reanalysis: Proof-of-concept for coupled DA in the satellite era
Dinand Schepers (ECMWF)
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Wednesday 24 January

Assimilation of sea surface temperature data in the FOAM ocean forecasting system
Matthew Martin (Met Office)
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Optimized assimilation of sea ice in an Earth system model and impacts for climate prediction
Madlen Kimmritz (NERSC)
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Assimilating SST with an atmospheric DA system
John Derber (NCEP)
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The Gulf Stream signature in sea surface temperature: observations and impact on the North Atlantic storm-track
Arnaud Czaja (Imperial College)
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Observation operators for sea Ice thickness to L-band brightness temperature
Matthias Drusch (ESA)
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Merged sea ice thickness product from complementary L-band and altimetry information
Stefan Hendricks (AWI)
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Sea ice data assimilation for NWP and operational ice services
Mark Buehner (Environment Canada)
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Organising committee

Magdalena A. Balmaseda, Patricia de Rosnay, Hans Hersbach, Sarah Keeley, Tony McNally, Steffen Tietsche