Spatial Analysis of Raster Data: Analyzing the Effects of Ice Removal and Sea Level Rise on the Physiography of Antarctica M. Helper, UT Austin On the Cutting Edge GIS Workshop1 Mark Helper Jackson School of Geosciences The University of Texas at Austin

GIS/GPS Applications in Earth Sciences Course and Students: M. Helper, UT Austin On the Cutting Edge GIS Workshop2  Only GIS class in the Department  Senior elective, cross listed as Grad. Course  20 students, TA  3 hrs. lecture, 2 hrs. lab per week  Prerequisite - intro. field geology with 3 hr expose to GIS base map prep., GPS data collection

Context: M. Helper, UT Austin On the Cutting Edge GIS Workshop3  First Lab with Raster Data Sets  Previous Labs/Lectures  Data Models – raster, vector  Projections  Digitizing, Georeferencing  ArcMap/Catalog basic  Preparation for Course Project

Raster Techniques/Tools: M. Helper, UT Austin On the Cutting Edge GIS Workshop4  Masking  Classifying and Symbolizing  Hillshade and Contour  Raster Calculations

Analysis Skills: M. Helper, UT Austin On the Cutting Edge GIS Workshop5  Raster Query Strategies  Highest/Lowest Elevations  Elevation at a point  Raster Statistics  Comparing Rasters  Raster Overlay  Land vs. Water  Area and Volume Calculations  Ice Sheet Properties

M. Helper, UT Austin On the Cutting Edge GIS Workshop6 Focus Questions:  Q1: What is the mean, maximum and minimum elevation of Antarctica?  Q2: What does Antarctica presently look like beneath the ice?  Q3: How much ice is there?  Q4: What would a “Greenhouse” Antarctica look like?

M. Helper, UT Austin On the Cutting Edge GIS Workshop7 Tools and Data  Tools – ArcGIS 9.x  Spatial Analyst (required)  3-D Analyst (optional; area and volume calculation)  Data – SCAR and BEDMAP sources  Posted for download as ~27 Mb Zip file

M. Helper, UT Austin On the Cutting Edge GIS Workshop8 Vector Data - Coverages  Point  South Pole  Arcs  Continent outline  Contours  Polygons  Land  Ice Shelves/Tongues

4.4 km :-2.6 km Bedrock Elevation (masked) M. Helper, UT Austin On the Cutting Edge GIS Workshop9 Raster Data (5x5 km ESRI Grids) 4.5 km 0 m Ice Thickness Surface Elevation 4.4 km M.S.L.

M. Helper, UT Austin On the Cutting Edge GIS Workshop10 Strategy: Explore, Map, Visualize, Analyze  Explore – Raster Properties, Metadata  Map/Visualize – Overlay and Symbolize  Analyze - Query and Model Questions basic to each step are inserted along the way

Explore the Data  Resolution  Data type  File size  Spatial Reference  Raster Stats. e.g. Q1: What are mean, max. min. elevations? M. Helper, UT Austin On the Cutting Edge GIS Workshop11

Explore the Data: Classify Elevations  Equal interval, 200m M. Helper, UT Austin On the Cutting Edge GIS Workshop12

Analysis Skills: Simple Raster Calculations M. Helper, UT Austin On the Cutting Edge GIS Workshop13  Conditional Statements and Binary Rasters Above or Below MSL Bedrock Elevation Con([bed_elev] <= 0,1)

Map/Visualize: Q2: What does Antarctica look beneath the ice? M. Helper, UT Austin On the Cutting Edge GIS Workshop14  Overlay binary raster with other layers and create a shoreline contour Above or Below MSL Bedrock Elevation =

Final Analysis: Q4: What would “Greenhouse” Antarctica look like? M. Helper, UT Austin On the Cutting Edge GIS Workshop15 1. Calculate new bedrock elevation raster that accounts for isostatic rise from ice removal; 2. Subtract from this new raster elevations equivalent to a higher sea leve l (~80 m); 3. Overlay a new binary land/sea raster Elevation change = (Density of ice / Density of Mantle) x (ice thickness)

Final Analysis: Prepare and Compare Final Maps M. Helper, UT Austin On the Cutting Edge GIS Workshop16 Bedrock Elevation TodayBedrock Elevation Greenhouse Conditions