Core theme 1: Sea ice
Recently we have seen strong indications of major changes in the arctic sea ice. Most dramatic has been the thinning of the Arctic ice-pack from more than 3m on average to less than 2m over a large part of the central basin of the Arctic Ocean.
The purpose of core theme 1 is to measure the variability of the essential climate variables that control sea ice.
Among the most disturbing modelling results are those predicting the disappearance of the Arctic perennial ice during this century. However the processes are far from clear.
We know the larger parts of the puzzle, but we do not yet know well enough how the various parts of the puzzle fit together. This is partly due to the fact that some processes are not yet well understood. The DAMOCLES strategy is to address these knowledge gaps by large-scale, long-term observations at high resolution. The purpose of core theme 1 is to measure the variability of the essential climate variables that control sea ice. The aim is to achieve synoptic coverage of the Arctic Ocean that will detect time- and space-scales of the variability of sea ice thickness, extent, concentration, type and drift. This will form a basis for assessing the future course of sea ice shrinkage, will help determine its impact on other environmental variables, and will provide a predicted date for the disappearance of the perennial sea-ice and for its replacement by a seasonal cover - one of the most extreme climatic events of the next few decades.
New technology makes it possible to build an adequate in situ system for the Arctic Basin, much of which has been developed and tested during recent FP5 programmes (SITHOS, GreenICE, IRIS and EuroClim). This core theme will feature strong input from related IPY projects (2007-9), Arctic GOOS, GCOS and ESA’s GMES programme.
The outputs from the in situ and satellite monitoring systems will be synthesized so as to yield a new synoptic view of Arctic ice thickness and other properties. Changes can be followed in great detail, with the specific experiments complementing the larger monitored view; for example, recent evidence that pressure ridges are disappearing from the Arctic at a relatively faster pace than the thinning of the ice as a whole can be reviewed in the light of AUV and submarine profiling experiments. The synthesized results will be fed to core theme 4 and used in models of ice-ocean-atmosphere processes which will yield a new and more dependable picture of the future of the Arctic Ocean.
Objectives:
- To measure the variability of sea ice thickness in the Arctic Basin. The aim is to achieve synoptic coverage of the Arctic Ocean so as to detect the time and space scales of variability in mean sea ice thickness, ice thickness probability density function (pdf), pressure ridge depths and frequencies, and lead widths and frequencies.
- To determine historical time series and operationally (NRT/1d) sea ice types and properties from satellite sensors for analysis of current state and for assimilation in oceanic and atmospheric models.
- To determine the effect of dynamics on the sea-ice thickness distribution and to validate and improve the physical description of sub-grid scale parameterizations of the redistribution of ice pack. The specific objectives are to i) determine scales of differential ice motion ii) relate differential ice motion to the changes of the ice thickness distribution iii) validate modelled evolution of the ice thickness distribution and iv) analyze variability of the ice thickness distribution.
- To quantify the role of thermodynamic sea ice processes in changes affecting the concentration, physical and structural properties and thickness, of Arctic sea ice.
