Expressions of Intent for IPY 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

Long term variability of the hydrographic structure, convection and transports in the Greenland Sea  (LOTEVA-GS)

Outline
Physical processes in the entire Polar Oceans are regarded with increased attention because of their high sensibility against climatic changes. This is also true for the hydrographic development in the Greenland Sea. Today it is clear that the straightforward idea of regular, repeated bottom water renewal in winter is not correct and that the previously proposed concepts for deep convection do not adequately describe the processes in the Greenland Sea. Since regular field expeditions have been started during the end of the 1980s, there was not a single year during which bottom water has been ventilated by winter convection. The doming structure of the 80s has been superseded by a marked two layer structure. In this situation, bottom water properties change towards higher temperatures and salinities. This can to a large part be explained by vertical displacement of the water column together with bottom water export. At the same time lateral inputs do also modify deep water as well as shallow water properties. Work during the recent years showed a.o. that even the seemingly simple identification of winter convection fails when using single criterions. In contrast to present knowledge, temperatures in a ventilated volume can be higher as well as lower after a convection phase. The same is true for salinities. The application of a more complex criterion catalogue shows that in the last decade winter convection penetrated to a density step in mid depth during most years. This density step is observed in increasing depths levels which leads to increasing convection depths. Consequently, these increasing depths are not synonymous with the ventilation of older water masses. The described two layered density structure is principally different from the dome structure of the early 1980s. Most recently, suprisingly long lived submesosclae vortices (SCVs) have been detected in the Greenland Sea (diameter about 10 to 20 km). In the centre of these features convection reaches depths that are about 1000 m greater than in the background (some 2600 m vs. 1600 m). These eddies seem to survive a number of years by a repeated homogenisation during winter. It is in the centres of these eddies where winter convection is expected to meet the ocean bottom first. In order to assess the importance of the SCVs an international cooperative effort will be made to follow the development of a single, relatively stationary SCV over some years. In all depth levels, the Greenland Sea represents a highly dynamical environment with considerable temporal changes. Our present knowledge about the relevant hydrographic processes does not allow to predict the future hydrographic development (including convective activity and transports) and consequently most of the analysis relies on field measurements. In order to assess the changes correctly and to gain an adequate perception of the processes, a longer time series is necessary. It has to comprise continuous and consistent observations including the water mass end members on the shelves. As convection history is established by comparisons between subsequent years, there should be no disruption of the time series (a one year gap leading to a loss of convection determination of two years). Within the proposed activity, a unique hydrographic time series is being established by an annually repeated zonal transect across the Greenland Gyre center and by measurements of autonomous profilers (EP/CC-Jojo, 2-daily profiles, full depth, 1 year exchange cycle) which give unprecedented insight to winter convective activity as well as to advective modifications.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
The project establishes a baseline to identify present and future changes in the polar environment and serves as a constituent of a synoptic set of observations to assess the status of the polar oceans in 2007/08. It helps to quantify and understand the present and future changes in the polar oceans and represents part of a key data set which is necessary to determine the factors controlling the dynamic change in the polar regions. Autonomous profiler measurements (EP/CC-Jojo, operationally working) provide unique observations of the ocean throughout the seasonal cycle in an unprecedented way. The autonomous profiler site establishes a multi-annual monitoring point (also included in GEO). The current composition and patterns of ocean circulation is determined in the Greenland Sea together with stratification and water mass modification. The previously unexpected spatial and short term variability is assessed, which often exceeds the annual amplitude and trend.

What international collaboration is involved in this project?
The project activity is part of the effort of a synoptic assessment of the Arctic. It is in particular related to the Synoptic Pan-Arctic Environment Study (SPACE). It incorporates international collaboration whenever possible (e.g. for sampling of Technetium, SF6, FCKW, ys, etc.; the analysis includes also chemical and optical parameters).

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
Greenland Sea

Approximate timeframe(s) for proposed field activities:
Arctic: 05/07 – 10/07      05/08 – 10/08      
Antarctic: n/a

Significant facilities will be required for this project:
Ice breaker or ice strengthened ship, 2-3 weeks. Shared use possible.

Will the project leave a legacy of infrastructure?
Operational monitoring site with autonomous profilers in the Greenland Sea.

How is it envisaged that the required logistic support will be secured?
Own national polar operator

Has the project been "endorsed" at a national or international level?
To the German IPY committee

PROJECT MANAGEMENT AND STRUCTURE

Is the project a short-term expansion (over the IPY 2007-2008 timeframe) of an existing plan, programme or initiative or is it a new autonomous proposal?
Expansion
Existing plan, to be incorporated into IGY

How will the project be organised and managed?
Self-managed. The proposed project should be included in the IPY for mutual benefits. It may be incorporated into a larger project.

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?
Routinely, students take part on cruises as well as journalists.

What are the initial plans of the project to address data management issues (as outlined in the Framework document)?
Not yet settled

How is it proposed to fund the project?
HGF programme funding

Is there additional information you wish to provide?
In order to avoid a disruption of the unique monitoring time series, the project should be imbedded into the IPY.

PROPOSER DETAILS

Dr Gereon Budéus
Alfred-Wegener-Institut
Columbusstr.
Bremerhaven
Bremerhaven
Germany

Tel: +49 471 4831 1702
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Other project members and their affiliation

Other Information