Welcome to the Ice Sheet System Model (ISSM) website. ISSM is the result of a collaboration between the Jet Propulsion Laboratory and University of California at Irvine. Its purpose is to tackle the challenge of modeling the evolution of the polar ice caps in Greenland and Antarctica.

ISSM is funded by the NASA Cryosphere and MAP (Modeling Analysis and Prediction) programs, JPL R&TD (Research, Technology and Developmnt) and NSF. Our main collaborators are: MSSMat Laboratory of École Centrale Paris and the Department of Geology of University of Buffalo, NY.

As synthesized in the last Intergovernmental Panel on Climate Change (IPCC) Assessment Report AR4, "future changes in the Greenland and Antarctic ice sheet mass, particularly due to changes in ice flow, are a major source of uncertainty that could increase sea level rise projections".

To remedy this problem, large scale ice flow models are necessary that can accurately model the evolution of Greenland and Antarctica in a warming climate. In order to achieve this goal, and improve projections of future sea level rise, ISSM relies on state of the art technologies, developed in synergy with the Research and Technology Development (R&TD) at JPL. These include:

Finite Element Modeling, which allows for the use of unstructured meshes to reach high resolutions in areas where ice flow dynamics is critical Parallel technologies, using state of the art clusters such as the NASA Advanced Supercomputing Pleiades cluster. This allows ISSM to run bigger models, with a faster turn around. Anisotropic mesh refinement, which allows ISSM to zoom in on areas of interest, while saving computational ressources by not refining meshes where ice flow is stagnant. Data assimilation using inverse methods in InSAR derived surface velocities, to infer basal drag coefficients and ice rheology. Multi-model methods, where different approximations for the dynamics of ice flow are solved in different areas, according to the type of flow encountered. This again saves a lot of computer time by only focusing on critical areas of an ice cap. Sensitivity analysis tools, based on the Dakota toolkit from Sandia National Laboratories. This suite of tools allows ISSM to constrain projections of future sea level rise, and to assess the reliability of such projections.

Modeled Antarctic surface velocity using ISSM