Knowledge Base

How to import the Greenland DEM into ArcGIS

Directions for Importing Bamber Greenland DEM, Ice Thickness, and Bedrock Thickness into ArcGIS 9.2

1. Download the ASCII files for Bamber Greenland Ice Thickness (this same methodology applies for bedrock thickness and surface thickness (DEM)).

2. Open up the downloaded ASCII file and attach the following header to the top (this step is required for step 3 to work).

ncols 301
nrows 561
xllcorner -802500
yllcorner -3402500
cellsize 5000

Make sure the file with this new header attached to the top is saved as a *.txt file

3. Open up ArcGIS → Open up ArcToolBox → Click on Conversion Tools → Then go to To Raster → Click on ASCII to Raster → In the ASCII to Raster input box do the following:

Input ASCII raster file: Select text file or files from Steps 1 and 2
Output Raster: Rename or use default name
Output Data Type (optional): Change to Float in Pull Down Menu

Click OK. An upside image of Greenland should appear

4. To flip this image go to ArcToolBox → Click on Data Management Tools → Go down and click on Projections and Transformations → Click on Raster → Then Flip → Follow the following steps in Flip input box:

Input Raster : Select Output Raster from step 3
Output Raster : Rename or use default name

Click OK. A image of Greenland in Step 3 should be flipped.

5. This new output raster needs to be converted to a North Pole Stereographic Projection. Go to ArcToolBox → Click on Data Management Tools → Go down and click on Projections and Transformations → Go to Define Projection and follow these steps in the Define Projection input box:

Input Dataset or Feature Dataset: Grab the output raster file that was created in
in step 4.
Under Coordinate System follow these steps:
- Click on hand/paper icon (right hand side of Coordinate System box)
- Hit Select button
- Select Projected Coordinate Systems folder (bottom one)
- Click on Polar folder (left-hand side 6th from bottom)
- Click on North Polar Stereographic.prj (5th from top) and an input box
should pop up
*In the new input box hit Modify Button and another input box should
pop up
*Under Projection make the following changes:
Name: Scroll Down to Stereographic_North_Pole (2nd one)
Central_Meridian: -39.00
Standard_Parallel_1: 71.00
*Keep everything else the same
Click OK and then OK two more times in the other input boxes.

6. The raster layer is now projected in a modified stereographic projection. Make sure the Data Frame has this same projection. To do so right click on the map section of ArcGIS and go to Data Frame Properties → Click on Coordinate System Tab → Click on → Hit the Import button on the right → Select the Output Raster in from Step 4 →Click Add → Click OK.