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detailed summary of observational data used by Reanalysis.
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|
background error used by the assimilation system (SSI).
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|
1/3/2000: Y2K problem: some observational data
were being incorrectly rejected. This problem only affected the 12/31/1999
analyses were fixed 1/3/2000 (6pm).
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News: Found a "truncation" error with the snow
analyses. Fixed Dec 1. More details to follow.
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Rotating Archives
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CDAS is now updated daily and the daily updates
are being stored in the "CDAS rotating archives." These archives include
more data than in our on-line historical archives such as four times daily
analyses and more daily-averaged fields. The historical archives will continue
to be updated once a month.
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Annual Reanalysis
CD-ROMs
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1950-2003 Reanalysis CD-ROMs
are now available. Contact
NCAR
for more information.
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The Reanalysis Synoptic CD-ROM with global 00Z
analyses from 1979-1996 is available. Fields on this CD-ROM include HGT
(1000 mb, 500 mb), WINDS (850 mb, 200mb) and OMEGA (500 mb). This CD-ROM,
like the annuals, is GrADS compatible and includes an MS-DOS menu system
and is available from
NCAR.
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What is it all about ?
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The NCEP/NCAR Reanalysis Project is a joint project
between the National Centers for Environmental Prediction (NCEP, formerly
"NMC") and the National Center for Atmospheric Research (NCAR). The goal
of this joint effort is to produce new atmospheric analyses using historical
data (1948 onwards) and as well to produce analyses of the current atmospheric
state (Climate Data Assimilation System, CDAS).
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Until recently, the meteorological community
has had to use analyses that supported the real-time weather forecasting.
These analyses are very inhomogeneous in time as there have been big improvements
in the data assimilation systems. This played havoc with climate monitoring
as these improvements were often produced changes in the apparent "climate".
Even fundamental quantities such as the strength of the Hadley cell has
changed over the years as a result of the changes in the data assimilation
systems.
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The quality and utility of the re-analyses should
be superior to NCEP's original analyses because
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a state-of-the-art data assimilation is used
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more observations are used
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quality control has been improved
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the model/data assimilation procedure will remain
essentially unchanged during the project
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many more fields are being saved (ex. potential vorticity
on isentropic surfaces, diabatic heating)
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global (some older analyses were hemispheric)
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better vertical resolution (stratosphere)
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For more information ...
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1996 BAMS Paper
(Bulletin of the American Meteorological Society)
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2001 BAMS Paper
(Bulletin of the American Meteorological Society)
(https)
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Misc. abstracts
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Types of Reanalysis Data
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Proc. of the First WCRP Intl. Conf. on Reanalysis
(Silver Spring MD, 27-31 Oct 1997) WCRP-104, WMO/TD-No. 876
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Reanalysis prior to 1958
|
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The effect of satellite and aircraft data on Reanalysis (pdf)
|
|
Detailed summary of observational data used by Reanalysis.
|
|
Background error used by the assimilation system (SSI).
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www.nws.noaa.gov 
