Using GRLevel3 To View Archived Radar Imagery

Note: These instructions are adapted from a post by the site administrator of the GRLevel3 user forum at www.grlevelx.com.

Process

  1. Create a folder on your local hard drive called "ArchivedRadarData" or something similar. This folder will be used to temporarily store and process archive radar downloads from the NCDC.

  2. Download the NCDCTORV3.EXE utility from http://www.grlevelx.com/downloads/ncdctorv3.exe and save it in the folder created in step one.

  3. To order archived data, navigate to http://hurricane.ncdc.noaa.gov/pls/plhas/has.dsselect and select the NEXRAD Level III option which takes you to the order form. From the order form, simply chose the individual radar station and the beginning and ending date of your search. It is also required that you enter your email address before clicking the Continue with Selections button.

  4. On the screen that follows, you have the option to order Untarred Contents or use FTP to retrieve the files from HDSS.

    • Untarred Option: This option allows you to select individual volume scans. Simply click on the volume scans you want and click the Order Data button. The screen that follows provides an order number (begins with HAS) and a hyperlink where you can monitor the status of your request. (Note: The resulting files are delivered by NCDC is .txt format and I have not been successful in importing these into GRLevel3. The remaining instructions assume that you are using a tarred file.)

    • Tarred Option: Tarred is a method used by the NCDC to zip all of the volume scans for the selected day into one file. This will probably provide data for a longer period than you are seeking, but it is a relatively easy way to retrieve the raw data. To retrieve a tarred file via FTP, select the button on the right side of the window named Retrieve Selected File. The system will provide a confirmation screen with the HAS number and a hyperlink to monitor the progress of your order.

  5. Although the system typically sends an email when your order is complete, I have experienced instances where no message was sent. For this reason, I always jot down the HAS number. If you have the HAS number, you can check the status of your order by typing it in the window at this web page.
  6. Once you receive the email announcing that your order is ready, click on the hyperlink and it will open a browser window containing the file(s). Right-click on the file(s) and save them to the folder created in step 1. If by some chance The tarred files can be large (50 to 70mb), so now might be a good time to freshen whatever beverage you are enjoying or get some fresh air.

  7. Now that you have downloaded that big .tar file, it is time to unzip and format the roughly 235 volume scans contained within it. This task is performed expeditiously by the ncdctorv3.exe that was downloaded in step two.

  8. NCDCTORV3.EXE must be run from the command line. The instructions that follow assume a Windows XP operating system. Select Start then Run from your XP menu. In the space just to the right of Open:, type in cmd and hit enter. This will present the command windows. If your computer is similar to mine, the command window opens to c:\Documents and Settings\Mark>. Before we can run ncdctorv3.exe, we must navigate to the folder where it and the .tar file is located. If you followed my suggestion in step 1, do the following:

  9. The path should now c:\ArchivedRadarData. You are now ready to unzip the .tar file and create the .rv3 files needed by GRLevel3. Execute the ncdctorv3.exe by typing ncdctorv3.exe, a space and the complete tar file name. Hit enter and you will be prompted to confirm that you wish to run the program. Hit Y and the program will execute. You should be left with roughly 250 .rv3 files that can be imported to GRLevel3.

  10. To view the volume scan, start GRLevel3. Use Windows Explorer to open the folder where your individual .rv3 files are located. Just click on the one that you want to view and drag it onto the GRLevel3 main window. Please note that the file name contains the date and GMT of the volume scan. Short loops can be created by selecting and dragging multiple files to the GRLevel3 window. Once the image is displayed, you can control the options just as if you were viewing live level III data.

  11. I suggest that you keep the C:\ArchivedRadarData folder ready for your next research project by copying the converted images into a folder dedicated to your current project.