Ice Sheet System Model 2017 (4.12) User Guide Authors: Mathieu Morlighem1 Hélène Seroussi2 Éric Larour2 Nicole Schlegel2 Chris Borstad2 Basile de Fleurian1 Surendra Adhikari2 Johannes Bondzio3 1University of California, Irvine, Department of Earth System Science, Croul Hall, Irvine, CA 92697-3100, USA 2 Jet Propulsion Laboratory - Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109 USA 3 Alfred Wegener Institute, Bremerhaven, Germany May 19, 2017 Contents 1 Download 14 1.1 Introduction........................................... 14 1.1.1 Binaries......................................... 14 1.1.2 Source Code...................................... 14 1.1.3 Become an ISSM developer !............................. 14 1.1.4 License......................................... 15 1.2 Binaries............................................. 15 1.3 Source installation of ISSM on UN*X systems........................ 15 1.3.1 Environment variables................................. 15 1.3.2 macOS.......................................... 16 1.3.3 External packages installation............................. 16 1.3.4 ISSM compilation................................... 17 1.4 Source installation of ISSM on Windows (under developement).............. 18 1.4.1 Win10.......................................... 18 1.4.2 Development Environment.............................. 18 1.4.2.1 Installing MATLAB............................. 18 1.4.2.2 Cygwin.................................... 19 1.4.3 Visual Studio...................................... 19 1.4.4 Building ISSM..................................... 20 1.4.4.1 Downloading ISSM............................. 20 1.4.4.2 Checking Your Build Environment..................... 21 1.4.4.3 Installing External Packages........................ 21 1.4.4.4 Building ISSM................................ 21 1.4.5 How to Setup a Cron Job............................... 22 1.5 Source installation of ISSM with AD capability (under developement).......... 22 1.5.1 External packages installation............................. 22 1.5.2 ISSM compilation................................... 23 2 CONTENTS 3 2 Getting started 24 2.1 Loading ISSM tools...................................... 24 2.1.1 MATLAB........................................ 24 2.1.2 Python......................................... 24 2.1.3 Developers....................................... 25 2.2 Model class........................................... 25 2.2.1 MATLAB’s model object............................... 25 2.2.2 Saving/loading a model................................ 26 2.3 Square ice shelf tutorial.................................... 27 3 Tutorials 28 3.1 Dataset download........................................ 28 3.2 Mesh adaptation........................................ 28 3.2.1 Goals.......................................... 28 3.2.2 Squaremesh....................................... 29 3.2.2.1 Usage..................................... 29 3.2.2.2 Example................................... 29 3.2.3 Roundmesh....................................... 30 3.2.3.1 Usage..................................... 30 3.2.3.2 Example................................... 30 3.2.4 Triangle......................................... 30 3.2.4.1 Usage..................................... 31 3.2.5 Bamg.......................................... 31 3.2.5.1 Usage..................................... 32 3.2.5.2 Uniform mesh................................ 32 3.2.5.3 Non-Uniform mesh.............................. 33 3.2.5.4 Mesh adaptation............................... 33 3.2.5.5 Mesh refinement in a specific region.................... 38 3.2.5.6 Another example............................... 41 3.3 Inverse method......................................... 41 3.3.1 Goals.......................................... 41 3.3.2 Introduction...................................... 41 3.3.3 Hands on 1 (ice rigidity, B).............................. 42 3.3.3.1 Setp 1: Generating Observations...................... 42 UCIrvine - Jet Propulsion Laboratory ISSM Documentation May 19, 2017 CONTENTS 4 3.3.3.2 Step 2: Initial guess and initial velocity.................. 43 3.3.3.3 Step 3: inverting for B........................... 43 3.3.3.4 Step 4: Adding regularization........................ 44 3.3.4 Hands on 2 (friction).................................. 45 3.3.4.1 Changes to step 1.............................. 45 3.3.4.2 Solutions to step 1.............................. 46 3.3.4.3 Changes to step 2.............................. 47 3.3.4.4 Changes to step 3.............................. 48 3.3.4.5 Solutions to step 3.............................. 49 3.3.4.6 Changing the cost function......................... 49 3.3.4.7 Solutions to step 3b............................. 50 3.3.4.8 Adding regularization............................ 51 3.3.4.9 Solutions to step 3c............................. 51 3.4 ISMIP test........................................... 52 3.4.1 Goals.......................................... 52 3.4.2 Introduction / How To................................. 52 3.4.3 Test A.......................................... 52 3.4.4 Simulation File Layout and Organization...................... 53 3.4.5 Mesh........................................... 53 3.4.6 Parameterization.................................... 55 3.4.7 Extrusion........................................ 56 3.4.8 Flow Equation..................................... 57 3.4.9 Boundary Conditions................................. 57 3.4.10 Solve Model....................................... 58 3.4.11 Test F.......................................... 59 3.4.12 Actual Work and Results............................... 59 3.5 Modeling Pine Island Glacier................................. 60 3.5.1 Goals.......................................... 60 3.5.2 Introduction...................................... 61 3.5.3 Setting-up domain outline............................... 61 3.5.4 Mesh........................................... 62 3.5.5 Mask.......................................... 64 3.5.6 Parameterization.................................... 65 UCIrvine - Jet Propulsion Laboratory ISSM Documentation May 19, 2017 CONTENTS 5 3.5.7 Inversion of basal friction............................... 65 3.5.8 Plot results....................................... 66 3.5.9 Higher Order (HO) Ice Flow Model.......................... 67 3.5.10 Solutions for step 6................................... 68 3.6 Pine Island Glacier, melting experiment........................... 69 3.6.1 Goals.......................................... 69 3.6.2 Evolution over 10 years................................ 69 3.6.3 Increased basal melting rate.............................. 70 3.6.4 Retreat of ice front position.............................. 71 3.6.5 Change in surface mass balance............................ 72 3.6.6 Evolution of the ice volume above floatation..................... 74 3.7 Uncertainty quantification (requires Dakota)......................... 75 3.7.1 Goals.......................................... 75 3.7.2 Introduction...................................... 75 3.7.3 Flux Gates....................................... 77 3.7.4 Loading Cross-Over Errors.............................. 78 3.7.5 Sampling Analysis................................... 78 3.7.6 Sensitivity Analysis.................................. 80 3.7.7 Plot Results....................................... 81 3.7.8 Additional Exercises.................................. 82 3.8 Jakobshavn Isbræ........................................ 82 3.8.1 Goals.......................................... 82 3.8.2 Introduction...................................... 83 3.8.2.1 Download................................... 83 3.8.3 runme file........................................ 83 3.8.4 Step 1: Mesh generation................................ 83 3.8.5 Step 2: Model parameterization............................ 84 3.8.6 Step 3: Control method................................ 84 3.8.7 Step 4: Display results................................. 85 3.9 Modeling the Greenland ice sheet............................... 86 3.9.1 Goals.......................................... 86 3.9.2 Introduction...................................... 86 3.9.3 Mesh........................................... 87 UCIrvine - Jet Propulsion Laboratory ISSM Documentation May 19, 2017 CONTENTS 6 3.9.4 Parameterization.................................... 88 3.9.5 Stress Balance..................................... 90 3.9.6 Transient........................................ 90 3.9.7 Exercise......................................... 92 3.9.8 Additional Exercises.................................. 95 3.10 Modeling the Greenland ice sheet using IceBridge data................... 96 3.10.1 Goals.......................................... 96 3.10.2 Introduction...................................... 96 3.10.3 Mesh........................................... 96 3.10.4 Parameterization.................................... 98 3.10.5 Stress Balance..................................... 102 3.10.6 Transient........................................ 103 3.10.7 Results......................................... 105 4 Capabilities 106 4.1 Mesh generation........................................ 106 4.1.1 ARGUS file format................................... 106 4.1.2 triangle......................................... 106 4.1.3 Bamg.......................................... 107 4.1.3.1 Domain.................................... 107 4.1.3.2 hmin/hmax.................................. 107 4.1.3.3 hVertices..................................