RIDGE
From APLIS07
Representations of Ice Deformation and Growth Experiment (RIDGE)
Coordinator: Max Coon, North West Research Associates
Project Summary
Calculations of the amount of open water generated by ice motion vary depending on the assumptions used to approximate the method of ice deformation. Most ice models assume that the velocity field is smooth and calculate ice deformation by differentiation. Yet, observations of ice motion show that most deformation occurs by three main mechanisms; the opening, closing or shearing of leads. A new generation of ice models are being developed interpret the velocity field such that it is composed of the motion of semi-rigid plates with permanent deformation occurring along the boundaries between the plates. These modeling efforts require the development of new constitutive equations to model the initiation and evolution of leads and ridges. Also, suitable numerical schemes are required which can handle the large deformations and history dependence of leads. The ice researchers involved in this proposal are currently working on a project funded by MMS, NASA and ONR to develop such a model. An elastic-decohesion constitutive model for sea ice has been developed and initial simulations have been run and compared with satellite-derived ice motion data. It is important that modeling efforts don’t evolve too far in a data vacuum, and field measurements are now needed to test the assumptions used to develop the constitutive equation.
Therefore, the ice researchers, Drs. Pruis and Coon, from NorthWest Research Associates will collect new data by deploying a GPS/Argos buoy array centered on an active lead/ridge system during the APLIS 2007 ice camp. An active lead system near the ice camp will be identified using SAR data before the buoy array is deployed. The array is designed and the data will be interpreted such that the assumptions in the new constitutive equation can be tested. The array will also be able to test the assumptions used for developing other constitutive equations in other ice models.
A unique aspect of this program is that it involves physics classes and teachers from Nathan Hale High School in Seattle, WA. Drs. Coon and Pruis have visited the classes several times and have led a field trip to the USCG ice breaker Healy. The students, after learning about our project, have been asked to write their own proposals to analyze the buoy data or to propose their own innovative research project. The students are familiar with differentiation and are learning about continuous and discontinuous functions. A panel of experts will evaluate the proposals, and the winner(s) of the competition will receive paid student intership(s) to work with Dr. Pruis on their data analysis project during the summer of 2007.
To ensure the ice motion data generated as part of this study is disseminated as broadly and as quickly as possible, the data management team of the recently funded European project DAMOCLES has agreed to disseminate the project’s data as part of their data stream. Additionally, the International Arctic Buoy Program will provide near-real time access to all the project data.
