CMG: Collaborative Research on Multi-Scale Predictions of Artic Ice Motion, Including Lead Orientation and Opening

University Of New Mexico, Albuquerque NM

Investigators

Abstract

Increasing our understanding of sea ice dynamics is vital because of the role sea ice plays in global atmospheric and ocean dynamics. In particular, the ability to better predict the opening of cracks in the ice, or leads, will improve our understanding of the Earth's weather, climate and ecology, as well as our ability to navigate Artic waters. Existing ice models have been of limited usefulness for forecasting the location and orientation of new leads and make no attempt to calculate the degree to which any given lead will open for predicted, or even observed forcing conditions. Even if effective models existed, until recently, there have been no data available for verification. We propose research that will exploit two significant developments and will ultimately allow accurate predictions of lead opening and orientation. First, motion of material points on large-scale regions of the Arctic ice cover have been recorded and are now available for complete winter seasons. Second, theoretical and numerical procedures have been recently developed for describing crack formation through the use of cohesive crack models. The proposed research is to develop a multi-scale, computational procedure to predict crack initiation, orientation, and width, in sea ice, under an observed set of loading conditions, and to verify the procedure using the newly available data. The successful completion of the research will set the stage for the next generation of models and numerical procedures in which realistic geophysical forces can be used to predict the detailed behavior of the Arctic ice cover. For the first time, large-scale motion data are available for points on the Artic ice cover. This unique dataset, produced by the Jet Propulsion Laboratory (JPL), is derived from high-resolution, spaceborn, Synthetic Aperature Radar (SAR) imagery, acquired by the RADARSAT satellite. These data are exactly what is needed to form a complete picture of ice deformation. A striking aspect of these images is linear features indicating the formation of leads, or openings in the sea ice. The ability to better predict the opening of leads will improve our understanding of the Earth's weather, climate and ecology, as well as our ability to navigate Artic waters. Existing ice models have been of limited usefulness for forecasting the location and orientation of new leads and make no attempt to calculate the degree to which any given lead will open for predicted, or even observed forcing conditions. Even if effective models existed, until recently, there have been no data available for verification. We propose to use the JPL data to develop and verify new material models for sea ice in order to predict crack initiation, orientation, and width. The successful completion of the research will set the stage for the next generation of models and numerical procedures in which realistic geophysical forces can be used to predict the detailed behavior of the Arctic ice cover. Moreover, sea ice is a central element in the Earth's climate system. An accurate ice model will benefit our ability to understand past climatic variability and to improve predictive capabilities through its inclusion in global ocean and climate models.