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Several options exist for you to use NCAR research data archives.

Open a NCAR account - See Obtaining Logins on Specific Computers section
Place a data order through chifan@ncar.ucar.edu or datahelp@ncar.ucar.edu (there will be a fee involved)
Monthly averages are available for free via ftp

Should you decide to place a data order, it helps us if you have the following information ready:

What are the variables you want?
Do you want analysis or forecast fields?
Starting and ending date/time?
How often? (i.e. every 6 hours or monthly)
What is the horizontal grid resolution? (i.e. 2.5 degree, Gaussian or zonal)
What is the vertical coordinate? (i.e. sigma, isentropic or pressure surfaces)
Which file type of reanalysis archive has the data you want?

Once we have received and confirmed the specifics of your data order, we'll provide an estimate of the cost as described in Reanalysis Data Ordering Information. Once the agreement of a data order is reached, your order will be processed. If you need the data in a hurry, please specify it clearly before the final agreement. A surcharge may apply to an rush order.

As your order is being processed, you need to get yourself familiar with the data formats used. For example, the NCEP/NCAR reanalysis data uses several formats: GRIB, BUFR, CRAY Binary, and ASCII. The details of GRIB BUFR and CRAY Binary formats are available in GRIB document BUFR document CRAY Binary. The NCEP/NCAR Reanalysis BUFR data follows the "PREPBUFR" format. You can find the decoder as PREPBUFR_ds090.0_extract.tar.Z

After your order is processed, the data tapes (preferably Exabyte tapes written in high density mode without compression) in Unix tar format (with a block size of 32768 octets) will be sent out. To retrieve the data files from Exabyte tapes, you can use Unix untar command with block specifciation. For example, if one block is 512 octets on your system, to extract 'grb3d85010112' from the Exabyte tape mounted on /dev/nrst0 drive, you use the following command:

tar xbf 64 /dev/nrst0 ./grb3d85010112

The extracted 'grb3d85010112' file is a GRIB file. You can use our GRIB decoder to decode the data. However, if you are not familiar with GRIB format, take a look at the GRIB document. You need to know how NCEP reanalysis grib.tbl2 and NCEP reanalysis grib.tbl3 are used.

If you are a GrADS user, you can use GrADS to display the GRIB file directly with correct control and map files. To use GrADS to display the data, you need all three files. The following examples are available in ds090.0/data/sampledata/grads:

pgb.f0085010100 - GRIB data file
pgb.f0085010100.map - GrADS GRIB map file
pgbf0085010100.ctl - GrADS control file

NCEP has additional GrADS utility programs such as: wgrib,grib2ctl, ts2synoptic,etc.

Also seeDSS Documentation

[Data Users Home Page]
[NCEP/NCAR Global Reanalysis Project]

[Acronyms Used] [Frequently Asked Questions]

updated 11/17/2004

Updated 22 July 2005