GIS Data and Resources at NSIDC

Importing SSM/I Daily and Monthly Sea Ice Concentration Data into ArcGIS

ArcGIS 9.x cannot read HDF data directly so the files must be converted into a readable format.

1. Download FWTools from http://fwtools.maptools.org/.

FWTools are a set of open source tools developed to convert, display, and project different raster and vector formats. These tools can be used at the command line as well as through the program OpenEV (distributed with the FWTools package). Follow the provided directions for installing FWTools.

2. Convert the HDF File to a GeoTIFF.

Once the full set of FWTools has been installed, open a command line shell and navigate to the HDF file. Use the following command.

gdal_translate -of GTIFF <in_dataset.*> <out_dataset.tif>

The gdal_translate command converts raster data sets into different formats. This command converts the HDF file into a GeoTIFF file. The new file is now in an ArcGIS readable format, but the file will still be missing a projection.

3. Define the Projection.

In ArcToolbox, navigate to Data Management Tools > Projections and Transformations > Define Projection. Navigate to the new data set, then click the button next to the coordinate system box. In the window that appears, choose New... > Projected... and specify a new name for the projection. Next, select Stereographic_(North or South)_Pole as the projection. Modify the Standard_Parallel_1 to equal (+/-) 70. Modify the Central_Meridian to -45 for the Northern Polar Stereo projection.

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 Greenwich for the Prime Meridian box. Click OK.

The data set is now appropriately projected.