Part 1—Download Software and Data
Step 1 – Download and Install ImageJ Software
ImageJ is in the public domain. It can be freely downloaded and installed on any computer including those at schools, homes, and businesses.- Go to the ImageJ Download page and open it in a new window.
- Click the link that appears directly below the name of your computer's operating system (e.g., Mac, Linux, Windows). This action will transfer a compressed file of the software to your computer. Your browser should automatically expand the file, creating an ImageJ folder on your computer's hard drive. For more detailed instructions from the ImageJ website, click Installation Instructions , then select your operating system.
Note to Windows Users: It is recommended that you install ImageJ in the Documents directory, rather than in the Program Files directory. For security reasons, Windows 7 and Windows Vista do not allow programs to alter themselves by writing files to the Program Files directory. If ImageJ is installed in the Program Files directory, then the update function in Step 2 below will not work properly. In addition, if you are a Windows Vista user, be sure to choose the correct version of ImageJ (either 32-bit or 64-bit) for your computer.
Step 2 – Update or Downgrade ImageJ
ImageJ update dialog box. Double-click the ImageJ icon 
to launch the application and choose Help > Update > ImageJ.... A window will appear, telling you the version you are currently running and a list of upgrade versions. Choose the version you want to upgrade to (usually the most recent, or default version) and click OK. After the update downloads, you will need to re-launch ImageJ to run the new version.
ImageJ update dialog box showing upgrade and downgrade options. ImageJ is a professional research and analysis tool, and is under constant development. If the latest update of the application introduces new bugs or errors, or has an unfamiliar interface that does not match written instructions, you can downgrade your copy of ImageJ to an older, more stable or familiar version.
Step 3 – Download Sea Ice Data from the National Snow and Ice Data Center (NSIDC)
- Download Sea Ice Data for the Arctic from the years 1978-2006 from the NSIDC website as a "tar" or compressed file. Click the Monthly Sea Ice data sets link to download the images in monthly order. Your computer will ask you what to do with the file. Simply save it to your downloads or desktop folder. Do not try to open it at this point in the lesson.
- A new window will open and the download will be ready to begin. A dialog box will ask you where to save the data.
- Create a new folder for all of the data and products of this exercise. Store it in a place you can access easily such as on your desktop or in your documents folder. The file that you are downloading is about 45 mb so it may take several minutes to download.
- Once the download is complete and the file is decompressed, you can check to see if you have the full dataset. Open the folder named pub and keep opening all the embedded folders until you have opened the monthly folder (buried 7 levels down). NOTE: Do not open these files, merely check that they are available.
- Familiarize yourself with the dates of each image from the file names. The first 4 digits indicate the year and next 2 digits tell the month. The "n" at the end of the file name indicates north. Scroll through the files and you will see that they are from 1978- present (2010). The first file name is nt_197810_f07_v01_n.bin. It represents sea ice concentration from October, 1978.
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