Ice Sheet Modeling at UAF

funded by NASA's Modeling, Analysis, and Prediction grant NNX09AJ38G and formerly by NASA Cryospheric Sciences

We maintain the Parallel Ice Sheet Model (PISM), which simulates the thickness, temperature, velocity and age of ice sheets.  New techniques for fast ice dynamics, earth deformation, and verification have been developed and included in PISM.  Simulations have used up to 500 processors on computers at the Arctic Region Supercomputing Center on the UAF campus. The major purpose is to simulate the Antarctic and Greenland ice sheets over time scales of complete ice-age cycles  (100,000+ years), and over the next few centuries.  Such simulations are the basis of estimates of eustatic and relative sea-level changes caused by ice dynamical response to changing climate. Students involved in this effort will work with a broad range of problems in the flow of the polar ice sheets and their interactions with the oceans, the climate, and the solid earth.  Students will apply modern high performance computing techniques and recent mathematical advances. Figures at right, clockwise from upper left: comparison of observed Jakoshavn isbrae, Greenland flow speeds in 1992 (left) and 2000 (right), from (Joughin et al 2004) ice stream in Palmer Land, Antartica; from (Post and LaChappelle, 2000) PISM-modeled vertically-integrated ice speed for Ross Ice Shelf, Antarctica, based on RIGGS and EISMINT-Ross data PISM-modeled surface speed for the Greenland ice sheet.  A 3km SeaRISE-Greenland grid.

Publications:

• Ed Bueler and Jed Brown (2009), Shallow shelf approximation as a "sliding law" in a thermomechanically coupled ice sheet model, Journal of Geophysical Research 114, F03008, doi:10.1029/2008JF001179.
• W. Lipscomb, R. Bindschadler, E. Bueler, D. Holland, J. Johnson, and S. Price (2009), A Community Ice Sheet Model for Sea Level Prediction, Building a Next-Generation Community Ice Sheet Model, A Workshop Held at Los Alamos National Laboratory, Los Alamos, New Mexico, 18-20 August 2008, Eos, Transactions 90 (no. 3).
  
• Ed Bueler (2008).  Lessons from the short history of ice sheet model intercomparison, The Cryosphere Discussions 2, 399-412.
  
• Ed Bueler, Craig S. Lingle, and Jed A. Brown (2007).  Fast computation of a viscoelastic deformable earth model for ice flow simulations, Annals of Glaciology 46, 97-105.
• Ed Bueler, Jed Brown, and Craig Lingle (2007).  Exact solutions to the thermomechanically coupled shallow ice approximation: effective tools for verification, Journal of Glaciology 53 (no. 182), 499-516.
• Ed Bueler, Craig S. Lingle, Jed A. Kallen-Brown, David N. Covey, and Latrice N. Bowman (2005). Exact solutions and the verification of numerical models for isothermal ice sheets, Journal of Glaciology 51 (no. 173), 291-306.
  

Preprints and technical reports:

• Ed Bueler, An exact solution to the temperature equation in a column of ice and bedrock, preprint arXiv:0710.1314, 2007.
  
• Ed Bueler and Jed Brown, On exact solutions for cold, shallow, and thermocoupled ice sheets, preprint arXiv:physics/0610106, 2006.
  
• Ed Bueler, Craig S. Lingle, Jed A. Kallen-Brown, Computation of combined spherical-elastic and viscous-half-space earth model for ice sheet simulation, preprint arXiv:physics/0606074, 2006.
• Ed Bueler, Craig S. Lingle, Jed A. Kallen-Brown, Latrice N. Bowman, and David N. Covey, Exact time-dependent similarity solutions for isothermal  shallow ice sheets, UAF DMS Technical Report 04-01, 2004. (20 pages, 406 KB, PDF)
• Ed Bueler, Construction of steady state solutions for isothermal shallow ice sheets, UAF DMS Technical Report 03-02, 2003. (7 pages, 183 KB, PDF)
• Ed Bueler, Numerical approximation of a two--dimensional thermomechanical model for ice flow, UAF DMS Technical Report 02-02, 2002. (51 pages, 449 KB, PDF)

Presentations & etc:

• E. Bueler, Numerical modelling of ice sheets and ice shelves (5MB, PDF; also see complete web page here), a short course given at Karthaus 2009 Summer School on Ice Sheets and Glaciers in the Climate System, September, 2009.
• E. Bueler, C. Khroulev, A. Aschwanden, and I. Joughin, Modeled and observed fast flow in the Greenland ice sheet , (6 MB, PDF).  Presentation at IGS International Symposium on Glaciology in the International Polar Year, Newcastle, UK, July 2009
• A. Aschwanden, E. Bueler, and M. Truffer, PISM-A Polythermal Parallel Ice Sheet Model (13MB, PDF), Poster at MOCA-09 Joint Assembly, Montreal, July 2009.
• Aschwanden and H. Blatter, Thermodynamics of Polythermal Glaciers and Ice Sheets (700KB, PDF), Poster at AGU Fall Meeting, San Francisco, Dec 2008.
• C. Khroulev, E. Bueler, C. Lingle, and J. Brown, Evaluating an Antarctic flow model (PISM) using InSAR surface velocities, (1.5 MB, PDF).  Poster at the 15th West Antarctic Ice Sheet (WAIS) Workshop, Oct. 2008, Sterling, Virginia.
• E. Bueler, Community tools for model initialization, spin-up, and evaluation, (2 MB, PDF).  Presentation at Los Alamos National Laboratory Workshop "Building a Next-Generation Community Ice Sheet Model", August 2008.
  
• E. Bueler, PISM, a Parallel Ice Sheet Model, (8 MB, PDF).  Presentation to ARSC Technology Panel, UAF, April 2008.
• J. Brown and E. Bueler, Superposition of velocity for ice flow modeling, (3 MB, PDF).  Presentation at the European Geosciences Union General Assembly, Vienna, Austria, April 2008.
• E. Bueler, Dynamics, Numerics, and Plain Old Ignorance; progress and problems in numerical ice sheet/stream/shelf modeling, (6 MB, PDF).  Presentation by Bueler at NYU CAOS Workshop "Predicting Sea Level in the 21st Century: The Role of Ice-Ocean Interaction", February 2008.
• E. Bueler, J. Brown, and C. Lingle.  A model of an ice sheet with one ice stream, (2 MB, PDF).  Presentation by Bueler at Fall AGU Meeting, San Francisco, December 2007.
• M. Truffer.  The challenge of predicting the glacial contribution to sea level rise.  Poster.  November 2007.
  
• C. S. Lingle, R. R. Muskett, and E. Bueler.  Ice Dynamics and the Accelerating Glacier and Ice Sheet Contributions to Rising Sea Level, (15 MB, PDF).  Presentation at the University of Puerto Rico, September 2007.
• E. Bueler, J. Brown, and C. Lingle.  The challenge of prediction: developing a polar ice sheet model capable of simulating the responses of ice shelves and ice streams to a warming ocean, (5 MB, PDF).  Presentation by Lingle at the University of Puerto Rico, September 2007.
  
• E. Bueler. Using PETSc for scientific computing in parallel, (PDF).  Presentation at the Arctic Regional Supercomputer Center (ARSC), UAF, June 2007. Gzipped tar file including three PETSc example codes and the PDF for the talk.
• E. Bueler. Ice sheet modelling at UAF and PISM, a Parallel Ice Sheet Model (PDF).  Presentation at the Arctic Regional Supercomputer Center (ARSC), UAF, June 2007.
• E. L. Bueler, C.S. Lingle, J. A. Brown, and D.N. Covey. Basal motion beneath the Antarctic ice sheet: a comparison of linear and plastic till rheologies in a multi-modal flow model (PDF).   Presentation at the European Geosciences Union General Assembly, Vienna, Austria, April 2007.
• R. Calov, R. Greve, P. Huybrechts, E. Bueler, C. Ritz, D. Pollard, F. Pattyn, and L. Tarasov. First results of the ISMIP-HEINO model intercomparison project (PDF).  Poster at the European Geosciences Union General Assembly, Vienna, Austria, April 2007.
  
• Ed Bueler.  On well-posedness and instability for steady temperature-dependent shallow ice flow, (1.5 MB, PDF).  Presentation at the SIAM Geosciences meeting, Santa Fe, NM, March 2007.
• Craig Lingle, Ed Bueler, Jed Brown, and David Covey.  PISM, a Parallel Ice Sheet Model: Current status of our Antarctic ice sheet simulation, (1 MB, PDF).  Presentation at the JPL PARCA meeting, 29--31 January 2007.
• Ed Bueler, Jed Brown, and Craig Lingle.  Verifying thermocoupled ice sheet models (and explaining the "warm spokes"), (3.5 MB, PDF). Presented at the 13th West Antarctic Ice Sheet Workshop, Pack Forest, Washington, September 2006.
• Craig Lingle, Jed Brown, and Ed Bueler, Multi-modal flow in a thermocoupled model of the Antarctic ice sheet, with verification, (958 KB, PDF).  Presentation at the International Glaciological Society Symposium on Cryospheric Indicators of Global Climate Change, Cambridge, England, August 2006.
• Ed Bueler, Craig S. Lingle, and Jed Brown, Fast computation of a viscoelastic deformable Earth model for ice sheet simulations, (444 KB, PDF).  Presentation at the International Glaciological Society Symposium on Cryospheric Indicators of Global Climate Change, Cambridge, England, August 2006.
• Ed Bueler, Ice Sheets and Obstacle Problems, (1.4 MB, PDF).  March 2006 UAF Dept. of Mathematics and Statistics Colloquium.
• Ellie Boyce, Roman Motyka, and Ed Bueler, Application of a 1-Dimensional Viscoelastic Bending Beam Model to the Buoyant Terminus of Lake-Calving Mendenhall Glacier, Southeast Alaska, American Geophysical Union, Fall Meeting 2005, abstract #C51A-0265.
• Craig Lingle, Ed Bueler, and Jed Kallen-Brown, Toward Multi-Modal Flow in a Thermomechanical Model of the Antarctic Ice Sheet.  Presentation at NW Glaciologist's Meeting, U.B.C., Oct. 21-22, 2005 and at the Oct. 24-26, 2005 planning meeting for NASA's Cryospheric Sciences Program.
• Ed Bueler, Jed A. Kallen-Brown, and Craig S. Lingle, Exact solutions and the verification of numerical models for ice sheets (250 KB, PNG format).  Poster at the European Geosciences Union 2005 General Assembly, Vienna, Austria. 
• Kallen-Brown, J.A., E.L. Bueler, C.S. Lingle, and D.N. Covey. A 3-D thermomechanical ice-sheet model: preliminary tests with the Goldsby-Kohlstedt flow law.  Presented at the 10th West Antarctic Ice Sheet Workshop, 17-20 Sept. 2003, Sterling, Virginia.
• Lingle, C.S., E.L. Bueler, J.A. Kallen-Brown, and D.N. Covey. A 3-D thermomechanical ice-sheet model: preliminary simulation of the Antarctic ice sheet with the Goldsby-Kohlstedt vs. Glen flow laws. American Geophysical Union, Fall Meeting 2003, abstract #C11C-0832.
• Ed Bueler, Introduction to the mathematics of ice flow. (263 KB, PDF).  September 2003 UAF Dept. Mathematical Sciences Colloquium.

Student work:

• Ben Sperisen, Ice Sheet Modelling: Numerics and Visualization, final paper and presentation from ARSC Undergraduate Research Challenge, Summer 2008.  Here are IDV animations by Ben Sperisen of PISM output (animated GIFs; from EISMINT-Greenland CCL3 runs; for illustration of visualization possibilities):
• modeled surface speed (color) over modeled surface elevation
• modeled -5^o C isotherm (temperature isosurface)
  
• Nathan Shemonski, Greenland in parallel, final paper from ARSC Undergraduate Research Challenge, Summer 2007.
• Jed Brown, Multi-modal ice sheet dynamics: theory and implementation, (2.5 MB, PDF).  UAF Master's Project defense, August 2006.
• Latrice Bowman, Numerical analysis of ice flow: numerical solutions using finite difference approximations, UAF Master's project, 2002.

Procedures/source codes for verification:

• The current suite of verification tests for PISM includes 12 different exact solutions, Tests A through L.  Source codes for all of these, and some documentation, are included in the open PISM source code and the User's Manual (see http://www.pism-docs.org/).  A python script is used to manage refinement paths and summaries of results: verifynow.py
  
• The paper Shallow shelf approximation as a "sliding law" ... includes PISM verification results for the plastic till SSA stress balance from Test I, using these C codes: exactTestsIJ.h, exactTestsIJ.c.  A simple driver program to evaluate this exact solution is  simpleI.c.
  
• The paper Exact solutions to the thermomechanically coupled shallow ice approximation ... includes PISM verification results from the following C codes implementing the exact thermocoupled solutions: exactTestsFG.h,  exactTestsFG.c.  A simple driver program to evaluate these exact solutions is  simpleFG.c.  Fortran 90 versions are:  testsFG.f90,  simpleFG.f90.
  
• The paper Fast computation of a viscoelastic deformable earth model ... includes results from four Matlab codes:  bedsheet.m,  fastearth.m,  geforconv.m,  viscdisc.m
  
• The paper Exact solutions and the verification of numerical models for isothermal ice sheets  includes five verification tests (A,B,C,D,E) and discussions of a transform method, margin approximation, and the EISMINT isothermal benchmarks.  The Matlab codes used in preparing the paper are here:  verifAE.m,   verifBC.m,  verifD.m,  verifBu.m,   verifEIS.m.   Versions of these tests in the PISM source code are here:  exactTestsABCDE.h,  exactTestsABCDE.c, and driver programs are simpleABCD.c and simpleE.c.  
  

Other public ice sheet models:

• GLIMMER is an open source SIA ice sheet model by Payne, Hagdorn, Rutt, et al. designed to couple to climate, ocean, etc models.  It has been verified with the isothermal exact solutions from Exact solutions and the verification... above.
• Ralf Greve's program SICOPOLIS is a polythermal SIA ice sheet model.
• ELMER/Ice is under development as a full Stokes ice sheet model in parallel.
  
• The Community Ice Sheet Model (CISM) is under development as a land ice component of the Community Climate System Model (CCSM), and will include a "higher-order" stress balance.
  
• The Interactive System for Ice Sheets (ISIS) is a Java graphical front end to ice sheet models.  Only GLIMMER for now.

Related sites:

Funding of our research:

• We are currently funded by NASA's Modeling, Analysis, and Prediction grant NNX09AJ38G.
• here is what we promised to do: Science, Technical, and Managment section of proposal GI_08-128
  
• it was selected under NASA solicitation NNH08ZDA001N-MAP