How to import the sea ice trends data into ArcGIS
The following are instructions describing how to import "Sea Ice Trends and Climatologies from SMMR and SSM/I-SSMIS" binary files into ArcGIS. These instructions were tested with ArcInfo 10.0.
1. Rename the Data File.
In order to be able to import a Polar Stereographic monthly climatology sea ice concentration file into ArcGIS, you will need to:
Rename the file extension, adding a .bil
Example: mean.apr.1979-2011.n to mean.apr.1979-2011.n.bil
2. Create a Header File.
In a text editor, create a new file with the content below. You will need to give the file the same name as the data file, but with a .hdr extension. Make sure that the .bil file and the .hdr file are saved in the same folder and are accessible to ArcGIS.
Content of the header file for Northern Hemisphere data:
Content of the header file for Southern Hemisphere data:
3. Convert the .bil File to an ESRI Compatible Grid Format.
Start ArcMap and open the ArcToolbox. Select Conversion Tools > To Raster > Raster to Other Format (multiple).
In the dialogue box that opens, select your .bil file as the Input Raster.
In the Output Workspace field, select the location to store the new data file. Choose ESRI Grid, ERDAS Imagine, or TIFF as the output raster format.
Click OK. The program will use your .hdr file to define your input raster and create a new, ESRI-compatible file.
4. Define the Projection.
In ArcToolbox, navigate to Data Management Tools > Projections and Transformations > Define Projection.
In the dialogue box that opens, choose your .bil file as the Input Dataset or Feature Class.
Next, click the button to the right of the Coordinate System input field.
In the dialogue box that opens, click New > Projected Coordinate System.
Enter a name of your choosing at the top of the next dialogue box.
In the Projection > Name drop-down menu, select Stereographic_(North or South)_Pole.
Modify the Standard_Parallel_1 to equal (+/-) 70.
Modify the Central_Meridian to -45 for the Northern Polar Stereo projection. For the Southern Hemisphere, leave the meridian as 0.
In the Geographic Coordinate System box select New.... In the new window enter a new name, then select the Datum to be <custom>. Leave the Spheroid option box<custom> and change the Semimajor axis to be 6378273 and in the Semiminor axis box enter 6356889.4. Next, change Angular Units to Degrees and choose Greenwichfor the Prime Meridian box. Click OK.
The data set is now appropriately projected.