Climate Observation and Modelling Expertise Team (COMET)

Summary

The Climate Observation and Modelling Expertise Team (COMET) aims to enhance the use of satellite-derived climate data in ocean and sea ice modelling.

Specifically, it focuses on improving the representation of ocean and sea ice processes in models by incorporating high-quality long-term Earth Observation records forEssential Climate Variables (ECVs) such as sea surface temperature, salinity, sea ice, and sea level - generated that have been generated via ESA’s Climate Change Initiative (CCI).

The project supports the advancement of the CMCC Earth System Model and contributes to the Coupled Model Intercomparison Project Phase 7 (CMIP7), helping shape the next IPCC assessment cycle. By applying advanced data assimilation, model calibration, and machine learning techniques, COMET addresses key scientific challenges in climate modelling, particularly in polar regions, and contributes to more accurate and reliable projections of future climate conditions.

Project Background

Climate models are essential tools for understanding the Earth system and guiding climate action. However, many models still show significant biases, especially in polar and ocean regions where in situ observations are sparse. Satellite-based Essential Climate Variables (ECVs) provide a unique opportunity to fill observational gaps and improve climate model calibration and performance. COMET responds directly to ESA’s Climate-Space initiative to enhance collaboration between the Earth Observation and modelling communities. It addresses scientific priorities highlighted by the IPCC, WCRP and GCOS, particularly the need to better represent the interactions between ocean, ice and atmosphere in Earth System Models. The project supports science-driven efforts, such as the Paris Agreement, by improving predictive capabilities in sensitive regions, such as the Arctic, where robust data and modelling are essential. These improvements are critical for future risk assessments, mitigation planning, and adaptation strategies. By focusing on the physical consistency, usability, and assimilation of satellite ECVs, COMET advances the climate modelling chain and increases the scientific and operational utility of ESA’s Climate Change Initiative products.

Project aims and objectives

COMET aims to enhance the use of satellite-derived climate data in ocean and sea ice modelling, focusing on three key objectives:

• Tailoring and harmonisation of ECV data: EO experts will reprocess CCI ECV datasets (SST, SSS, Sea Level, SIC/SIT) to meet the technical and scientific requirements of climate models. Activities include regridding, uncertainty characterisation, and temporal alignment.
• Improved data assimilation and model calibration: The tailored data will be used in the global reanalysis system (e.g. C-GLORS by CMCC), enhancing the coupled ocean–sea-ice model by incorporating cross-variable correlations. The work will result in improved ocean and sea-ice fields for climate studies and reanalysis products.
• Development of new methodologies: testing novel approaches such as machine learning tools to improve the representation of EO data within data assimilation systems and to support next-generation model calibration strategies.

Results will directly support the upcoming CMIP7 and IPCC cycles. The project will also develop recommendations for improving future CCI products and publish scientific findings in peer-reviewed journals.

COMET is organised into five work packages:

• WP100: Science Requirements – Led by CMCC, this task defines the key scientific priorities and requirements for using EO data in modelling systems.
• WP200: Data Preparation – Led by ICM-CSIC, this task adapts EO datasets to ensure compatibility with model needs, focusing on reformatting, bias correction and quality control.
• WP300: Scientific Analysis – Led by CMCC, this task integrates tailored datasets into climate models to evaluate the impact of EO data on model performance.