Looking for sample code for reading and visualizing NSIDC’s HDF data?

Hierarchical Data Format (HDF) supports a variety of data types and allows for the transfer and manipulation of scientific data across diverse operating systems and computer platforms. It was developed by the HDF Group at the University of Illinois and is the standard data format for all NASA Earth Observing System (EOS) data.

A variety of HDF data are distributed at NSIDC, including data from the AMSR-E, MODIS, and GLAS sensors as well as the NISE data set.

Despite the versatility of HDF, some data users have had difficulty in reading and displaying HDF data and often ask if we have sample code for reading HDF data in programs such as IDL and MATLAB.

Fortunately, the HDF Group provides sample code for access and visualization of HDF data into IDL, MATLAB, and NCL. Access to the sample code for NSIDC HDF data is provided on the HDF Group’s HDF-EOS Comprehensive Examples Web page.

Also note that this information can be found in our Online Support under the AMSR-E, MODIS, GLAS, and NISE forums.

Sample Matlab plot of AMSR-E 12km Sea Ice

Sample plot generated in MATLAB from AMSR-E 12km Sea Ice data (from http://hdfeos.org/zoo/).

Tips for working with NSIDC’s most popular sea ice concentration data

NSIDC’s sea ice concentration data are used by scientists and students, journalists and advisers. The range of possible uses for the data is as varied as the data users themselves. The biggest hurdle encountered by many users is simply learning how to initially read and display the data. Here are some tips on how to get started.

The “Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data” are distributed in gridded binary format. NSIDC provides IDL routines to ingest and read the data. These tools can be found at the Polar Stereographic Tools Web page.

However, if you are unfamiliar with IDL, there are other options that you can use. First of all, you may be interested in downloading the data via the Polaris search and order interface. This Web tool allows you to download the data in GeoTIFF or NetCDF formats. It also allows you to make spatial and temporal constraints on the data as well as change the output projection.

If you are interested in importing the data to ArcGIS, you can either use the GeoTIFF files downloaded from Polaris (see above), or you can perform a few steps to import the native binary files. In order to do this, you will need to rename the files, create a header file for the data, and use ArcToolbox to transform the files to a different format. Instructions detailing how to do this can be found in this Online Support article.

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