Core theme 4: Integration and data assimilation in large-scale modelling and forecasting - DAMOCLES - Understanding climate change in the Arctic

This core theme aims to integrate observations and modelling by combining output from the observation-and process-oriented themes 1-3 (and IPY and non-DAMOCLES observations) with dedicated regional and global scale numerical modelling.

Theme 4 thus forms a basis for the scientific conclusions of DAMOCLES, especially on the mechanisms involving natural variability and long-term changes of the extent, thickness and composition of the Arctic sea ice.

This core theme is fully embedded in the DAMOCLES IP as it provides input to the impact activities (sensitivities, actual and potential predictability, model improvements, appropriate choice of assimilation tools etc), as well as informing the issue of data storage, and returning feedback for the better design of field operations under core themes 1-3.

The modelling work provides validated and improved models whose sensitivities and underlying processes will have been explored and understood on daily to decadal timescales. As a result we will hope to approach the limits of predictability of the inherent natural variability of the arctic. These models can then be used to assess and enhance observational data in 4D dynamically balanced representations (“analyses” and “reanalyses”), to improve weather forecasts and to perform more reliable climate scenarios.

These capabilities represent a strong part of the DAMOCLES outreach, as the system can be applied even after the end of the DAMOCLES period in a planned ‘legacy phase’ Arctic modelling and observation system

Objectives

To progress the understanding of the fate of sea ice and its interaction with ocean and atmosphere by means of observation-supported model improvement and sensitivity studies.
To quantify the effects of improved understanding and process description or assimilation techniques on simulation capabilities.
To develop assimilation methods with the goal of producing fields of key arctic variables for the DAMOCLES period that combine information from observations and models.

Description of work

This core theme is subdivided into three activities with different types of end product. Activity 1 provides improved models, process understanding and sensitivities. Activity 2 focuses on quantifying predictability and improving prediction capabilities by means of ensemble runs and data assimilation schemes, together with the associated developments and improvements that that entails. Activity 3 builds on developments and improvements from activities 1 and 2 and focuses on the methods for production of enhanced gridded 4D datasets (“analysis”) and the associated development of specific DAMOCLES data-oriented assimilation schemes.

A choice of DAMOCLES WP4 external activities:

The S4D workshop on Arctic modelling

The S4D workshop on Arctic modelling was held in Paris on Oct 29-31 2007 The major goal of the workshop was to coordinate modeling activities between DAMOCLES and the US-SEARCH program and to link activities with AOMIP and (C)ARCMIP projects during IPY and beyond.

Though the workshop is targeting at modeling activities, observers were strongly encouraged to attend the workshop as well. Some tasks were specifically designed to stimulate the discussion between modellers and observers. The workshop was organized under dedicated guidance of DAMOCLES WP4 and was featuring several specific WP4 contributions in the fields of Arctic predictability, 20th century simulations, data assimilation, reanalysis products, network optimization, Atlantic water circulation, radiation parameterization, atmospheric boundary layer processes, and importance of tidal processes. The results of the workshop are published in a report (Proshutinsky A., Dethloff K. , Döscher R. , Gascard J.C. and F. Kauker, 2008: Toward reduction of uncertainties in Arctic climate simulations", accepted for publication by EOS) Further information on the workshop is given on the S4D webpage.

The Arctic ocean session (OS7) at the EGU meeting 2008, Apr 14-19 2008

For this session we encourage presentations on from DAMOCLES and other projects, covering processes in ocean, atmosphere and ice, affecting Arctic or Antarctic oceans with their varying ice cover and interaction with the global oceans. Observational studies are as welcome as reconstruction and modeling results of past, recent and possible future climate in the polar regions.

The session is organized and lead by Ralf Döscher (DAMOCLES WP4) , Ursula Schauer (DAMOCLES WP3) and Cecilie Mauritzen (DAMOCLES WP3). For a list of contributions including several DAMOCLES WP4 presentations, please consult the EGS OS7 webpage.

Feb 10, 2007

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Nov 10, 2008