Climate Data Assimilation System

NCEP/NCAR Reanalysis (CDAS) is run in real time. Since the other sources of Reanalysis data (CDC, NCAR, NCDC) may not be able provide the data in a timely manner, a subset of the current CDAS data is available by the Internet. The subset includes monthly and daily averages of many standard pressure-level data and surface flux quantities. We expect (but do not promise) that the historical archives will be updated by the fifth of the month for the preceding month. The rotating archives will contain the latest analyses and is usually updated a few days after the fact.

On-line Access to the Data

We as well some other groups (ex. CDC, NCAR, IRI) make some of the data available on-line. Our web facilities allow you to (1) make plots, (2) obtain time series of a box average, (3) obtain subsets of the GRIB fields and (4) FTP access to many of the GRIB fields. We have the historical 4x daily data and monthly mean data. We also have a rotating archives of the 4x daily and daily means from the latest analyses (a few day delay). All the data can be obtained from (4x daily, monthly, rotating archive)

Links to the Data

Information about the data :
Reading GRIB
4x Daily, monthly, daily-averaged rotating archive:

Questions and Support

Details of Reanalysis/CDAS are explained the March 1996 issue of the Bulletin of the American Meteorology Society (BAMS). Some questions about Reanalysis can be answered by the standard Reanalysis data distributors. and by the various WEB pages about Reanalysis.

The CDAS data is in GRIB, and problems with reading GRIB files are history.

Home Sweet Home

Problems: contact or

Privacy Policy