NEXRAD HDSS Access Tutorial

This tutorial guides the user through the Nexrad portion of the HDSS Access System (HAS).

The HDSS is the robotic tape assembly used to store large datasets at NCDC. The data must be transferred from the tapes onto the public ftp site. The HAS web interface allows users to order Nexrad data from the tape archive. An average sized order takes 5-25 minutes to post on the ftp site.

  1. Go to the HAS website: and select the type of data desired.
    Level-II is the raw data, Level-III is a collection of derived products.

  2. Now choose the type of retrieval. Using the Stations(s) option usually provides an easier search for specific data.

  3. If Entire Dataset is selected, then choose date range.

  4. If Station(s) is selected, then choose station (hold shift or control for multiple) and date range.

  5. After entering your email, choose the desired files. The 4-letter Nexrad Site ID and date are included in the filename.
    NOTE: The "UnTar Files After Retrieval" option allows for the files to be uncompressed for the user. This option is useful when only select dates or products are needed. Individual Level-II files will still have unix compression after retrieval.

  6. If you have chosen to "UnTar Files After Retrieval" select the desired individual files. Multiple files may be selected by holding shift or control during selection. The filename format is as follows:

    Level-II Example) KAKQ 20030919_ 210227 .Z - 495042
    KAKQ = Source Radar Site ID
    20030919 = Date in YYYYMMDD format (year=2003, month=09, day=19)
    210227 = Time in HHMM format Z/UTC time (hour=21, minutes=02)
    .Z = Unix compression extension
    495042 = Size of file in Bytes
    Level-III Example) KAKQ SDUS51_ N0R AKQ_ 20030919 2102 - 11730
    KAKQ = Site ID of transmitting radar (not necessarily source radar)
    SDUS51 = Transmission info
    N0R = Product Code (Product List)
    AKQ = Source Radar Site ID (ACTUAL SITE OF THE DATA!)
    20030919 = Date in YYYYMMDD format (year=2003, month=09, day=19)
    2102 = Time in HHMM format Z/UTC time (hour=21, minutes=02)
    11730 = Size of file in Bytes

  7. You have now submitted an order to the HDSS System. An email will be sent to you when the order has been completely posted to the ftp site.

  8. The email with the HAS Job Number and instructions on data access.
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Last Updated Wednesday, 20-Aug-2008 12:06:33 EDT
Please see the NCDC Contact Page if you have questions or comments.