Expressions of Intent for International Polar Year 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

Ice and snow mass change of Arctic & Antarctic polar regions from GRACE satellite gravimetry  (GRACE)

Outline
The main objective of this proposed work is the study of ice/snow mass time-variations over polar regions, the estimation of the water mass balance using monthly GRACE geoids for the recent period, as well as its connection with the global climate change, the global hydrological cycle, and in particular the investigation on the possible causes of the sea level rise from important ice melting. On-going GRACE mission (launched in 03/2002 for a nominal lifetime of 5 years) provides monthly maps of tiny spatio-temporal variations of gravity due to the redistributions of massinside the surface fluid envelops of the Earth. These satellite measurements represent vertically-integrated gravity effects of water mass reservoirs (oceans, atmosphere, continental waters) and of the solid Earth that need to be unravelled. Monthly solutions of the continental storage (2002 – present) have been recently extracted from the raw GRACE geoids (at the resolution of 500 km), and using an iterative generalized least-squares approach developed in our laboratory (LEGOS). After correction of important geophysical effects like mass changes induced by vertical movements (mainly post-glacial rebound), these solutions can be directly used over high-latitude ice sheets for (1) mapping for the first time the regional variations of loss/gain of ice mass; (2) estimating the water mass balance of these polar regions, which can be expressed in terms of sea level contribution and thus compared to the non-steric values deduced by combining observations of the sea level from satellite altimetry and estimates of the ocean thermal expansion; (3) proposing different climate scenarii to explain the transfers of mass between frozen polar regions of Arctic and Antarctic and the other water mass reservoirs (oceans, atmosphere). Another objective of the study is to monitor the snow pack changes in the Arctic regions using GRACE satellite gravimetry. Our results will be compared with in situ observations (absolute gravimetry) and from other satellite techniques.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
Estimating the mass balance of the ice sheets is the key for understanding the climate change and its recent evolution. As in situ geophysical measurements over remote polar regions remain very local and rare, GRACE satellite gravimetry offers the advantages of being systematic and observations of the vertically-integrated mass changes at a minimum resolution of 500 km. Because of its quasi-polar orbit, GRACE provides denser so more accurate spatially-distributed gravity measurements at high latitudes, and will enable to estimate of the ice mass balance, for the very first time. Similarly, GRACE will monitor changes in mass of the snow pack of the Arctic regions.

What international collaboration is involved in this project?
GFZ (Germany)University of Texas at Austin (USA)

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
Antarctica Arctic regions

Approximate timeframe(s) for proposed field activities:
Arctic: Multi-year period            
Antarctic: Multi-year period            

Significant facilities will be required for this project:
Satellite (remote sensing data from the GRACE space mission)

Will the project leave a legacy of infrastructure?

How is it envisaged that the required logistic support will be secured?

Has the project been "endorsed" at a national or international level?
Not yet. A proposal will be sent to CNES in spring 2005 for support in data analysis

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?
no

The proposing team is already involved in GRACE data analysis for global land hydrology over the lifetime of the mission (2002- )

How will the project be organised and managed?
The project will be self-managed

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?
Results will be regularly communicated to public via outreach departments of large scientific institutes (e.g., CNRS, CNES,…)

What are the initial plans of the project to address data management issues (as outlined in the Framework document?
Monthly GRACE data we will use are currently pre-processed by the GFZ (Potsdam) and the CSR (Univ. of Texas) and freely available.

How is it proposed to fund the project?
A proposal for data analysis funding will be sent to CNES in Spring 2005

Is there additional information you wish to provide?
None

PROPOSER DETAILS

Dr Guillaume Ramillien
LEGOS
14 avenue Edouard Belin
31400 Toulouse cedex 9
31401
France

Tel: +33 5 61 33 29 30
Mobile: no
Fax: +33 5 61 25 32 05
Email:

Other project members and their affiliation